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Sample records for apomixis

  1. On the origin and evolution of apomixis in Boechera

    NARCIS (Netherlands)

    Lovell, J.T.; Aliyu, O.M.; Mau, M.; Schranz, M.E.; Koch, M.; Kiefer, C.; Song, B.H.; Mitchell-Olds, T.; Sharbel, T.F.

    2013-01-01

    The genetic mechanisms causing seed development by gametophytic apomixis in plants are predominantly unknown. As apomixis is consistently associated with hybridity and polyploidy, these confounding factors may either (a) be the underlying mechanism for the expression of apomixis, or (b) obscure the

  2. Apomixis in hawkweed: Mendel's experimental nemesis.

    Science.gov (United States)

    Koltunow, Anna M G; Johnson, Susan D; Okada, Takashi

    2011-03-01

    Mendel used hawkweeds and other plants to verify the laws of inheritance he discovered using Pisum. Trait segregation was not evident in hawkweeds because many form seeds asexually by apomixis. Meiosis does not occur during female gametophyte formation and the mitotically formed embryo sacs do not require fertilization for seed development. The resulting progeny retain a maternal genotype. Hawkweeds in Hieracium subgenus Pilosella form mitotic embryo sacs by apospory. The initiation of sexual reproduction is required to stimulate apospory in ovules and to promote the function of the dominant locus, LOSS OF APOMEIOSIS, which stimulates the differentiation of somatic aposporous initial (AI) cells near sexually programmed cells. As AI cells undergo nuclear mitosis the sexual pathway terminates. The function of the dominant locus LOSS OF PARTHENOGENESIS in aposporous embryo sacs enables fertilization-independent embryo and endosperm development. Deletion of either locus results in partial reversion to sexual reproduction, and loss of function in both loci results in reversion to sexual development. In these apomicts, sexual reproduction is therefore the default reproductive mode upon which apomixis is superimposed. These loci are unlikely to encode factors critical for sexual reproduction but might recruit the sexual pathway to enable apomixis. Incomplete functional penetrance of these dominant loci is likely to lead to the generation of rare sexual progeny also derived from these facultative apomicts.

  3. An Apomixis-Gene’s View on Dandelions

    NARCIS (Netherlands)

    Dijk, van P.; Jong, de J.H.S.G.M.; Vijverberg, K.; Biere, A.

    2009-01-01

    In asexual organisms, the clone constitutes a level above the individual. Most dandelions (Taraxacum officinale s.l.) reproduce asexually through apomixis, asexual reproduction through seeds. A clone can be seen as a superorganism that is born, that growths, degenerates and eventually dies. Apomixis

  4. La apomixis, su estudio y posibles usos

    OpenAIRE

    Meier, Mauro Sebastián; Zappacosta, Diego Carlos; Selva, Juan Pablo; Cervigni, Gerardo; Echenique, Carmen Viviana

    2017-01-01

    La apomixis es una forma de reproducción asexual a través de semillas que origina plantas genéticamente idénticas a la planta madre (clones). Su estudio para entender el funcionamiento, herencia y regulación a nivel génico de este fenómeno en pasto llorón puede traer grandes beneficios para la agricultura y la alimentación humana. Fil: Meier, Mauro Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos...

  5. Molecular markers linked to apomixis in Panicum maximum Jacq ...

    African Journals Online (AJOL)

    Panicum maximum Jacq. is an important forage grass of African origin largely used in the tropics. The genetic breeding of this species is based on the hybridization of sexual and apomictic genotypes and selection of apomictic F1 hybrids. The objective of this work was to identify molecular markers linked to apomixis in P.

  6. Apomixis frequency under stress conditions in weeping lovegrass (Eragrostis curvula.

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    Juan Manuel Rodrigo

    Full Text Available To overcome environmental stress, plants develop physiological responses that are triggered by genetic or epigenetic changes, some of which involve DNA methylation. It has been proposed that apomixis, the formation of asexual seeds without meiosis, occurs through the temporal or spatial deregulation of the sexual process mediated by genetic and epigenetic factors influenced by the environment. Here, we explored whether there was a link between the occurrence of apomixis and various factors that generate stress, including drought stress, in vitro culture, and intraspecific hybridization. For this purpose, we monitored the embryo sacs of different weeping lovegrass (Eragrostis curvula [Schrad.] Nees genotypes after the plants were subjected to these stress conditions. Progeny tests based on molecular markers and genome methylation status were analyzed following the stress treatment. When grown in the greenhouse, the cultivar Tanganyika INTA generated less than 2% of its progeny by sexual reproduction. Plants of this cultivar subjected to different stresses showed an increase of sexual embryo sacs, demonstrating an increased expression of sexuality compared to control plants. Plants of the cv. Tanganyika USDA did not demonstrate the ability to generate sexual embryo sacs under any conditions and is therefore classified as a fully apomictic cultivar. We found that this change in the prevalence of sexuality was correlated with genetic and epigenetic changes analyzed by MSAP and AFLPs profiles. Our results demonstrate that different stress conditions can alter the expression of sexual reproduction in facultative tetraploid apomictic cultivars and when the stress stops the reproductive mode shift back to the apomixis original level. These data together with previous observations allow us to generate a hypothetical model of the regulation of apomixis in weeping lovegrass in which the genetic/s region/s that condition apomixis, is/are affected by ploidy

  7. Apomixie, sexualité et amélioration des graminées tropicales

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    Gobbe, J.

    1983-01-01

    Full Text Available Apomixis, sexuality and improvement of tropical grasses. Gametophytic apomixis together with sexuality can be used for the improvement of tropical grasses. Apomixis is researched for providing an easy spreading of cultivars. Apomictic and sexual species are found in the genus Brachiaria ; hybridizations are carried out between a tetraploid, colchicine induced form of the sexual species B. ruziziensis Germain et Evrard, and natural tetraploid apomicts, B. brizantha Stapf. and B. decumbens (Hochst Stapf.

  8. Apomixis: Engineering the Ability to Harness Hybrid Vigor in Crop Plants.

    Science.gov (United States)

    Conner, Joann A; Ozias-Akins, Peggy

    2017-01-01

    Apomixis, commonly defined as asexual reproduction through seed, is a reproductive trait that occurs in only a few minor crops, but would be highly valuable in major crops. Apomixis results in seed-derived progenies that are genetically identical to their maternal parent. The advantage of apomixis would lie in seed propagation of elite food, feed, and biofuel crops that are heterozygous such as hybrid corn and switchgrass or self-pollinating crops for which no commercial-scale hybrid production system is available. While hybrid plants often outperform parental lines in growth and higher yields, production of hybrid seed is accomplished through carefully controlled, labor intensive crosses. Both small farmers in developing countries who produce their own seed and commercial companies that market hybrid seed could benefit from the establishment of engineered apomixis in plants. In this chapter, we review what has been learned from studying natural apomicts and mutations in sexual plants leading to apomixis-like development, plus discuss how the components of apomixis could be successfully engineered in plants.

  9. Evolution of apomixis loci in Pilosella and Hieracium (Asteraceae) inferred from the conservation of apomixis-linked markers in natural and experimental populations

    Czech Academy of Sciences Publication Activity Database

    Hand, M. L.; Vít, Petr; Krahulcová, Anna; Johnson, S. D.; Oelkers, K.; Siddons, H.; Chrtek, Jindřich; Fehrer, Judith; Koltunow, A. M. G.

    2015-01-01

    Roč. 114, č. 1 (2015), s. 17-26 ISSN 0018-067X R&D Projects: GA ČR GA206/08/0890; GA ČR GAP506/10/1363 Institutional support: RVO:67985939 Keywords : gametophytic apomixis * Hieracium * marker inheritance Subject RIV: EF - Botanics Impact factor: 3.801, year: 2015

  10. Apomixis is not prevalent in subnival to nival plants of the European Alps

    Czech Academy of Sciences Publication Activity Database

    Hörandl, E.; Dobeš, C.; Suda, Jan; Vít, Petr; Urfus, Tomáš; Temsch, E. M.; Cosendai, A.-C.; Wagner, J.; Ladinig, U.

    2011-01-01

    Roč. 108, č. 2 (2011), s. 381-390 ISSN 0305-7364 Institutional research plan: CEZ:AV0Z60050516 Keywords : apomixis * endosperm * flow cytometric seed screen Subject RIV: EF - Botanics Impact factor: 4.030, year: 2011

  11. The occurrence of phenotypically complementary apomixis-recombinants in crosses between sexual and apomictic dandelions ( Taraxacum officinale ).

    NARCIS (Netherlands)

    Dijk, P.J.; Baarlen, van P.; Jong, de J.H.S.G.M.

    2003-01-01

    Apomictic seed development in dandelion (Taraxacum officinale) involves (1) restitutional meiosis (diplospory), (2) egg cell parthenogenesis, and (3) autonomous endosperm development. The question is whether these elements of apomixis are controlled by one single gene or by several independent

  12. The occurrence of phenotypically complementary apomixis-recombinants in crosses between sexual and apomictic dandelions (Taraxacum officinale)

    NARCIS (Netherlands)

    Van Dijk, P.J.; Van Baarlen, P.; De Jong, J.H.

    2003-01-01

    Apomictic seed development in dandelion (Taraxacum officinale) involves (1) restitutional meiosis (diplospory), (2) egg cell parthenogenesis, and (3) autonomous endosperm development. The question is whether these elements of apomixis are controlled by one single gene or by several independent

  13. A methylation status analysis of the apomixis-specific region in Paspalum spp. suggests an epigenetic control of parthenogenesis.

    Science.gov (United States)

    Podio, Maricel; Cáceres, Maria E; Samoluk, Sergio S; Seijo, José G; Pessino, Silvina C; Ortiz, Juan Pablo A; Pupilli, Fulvio

    2014-12-01

    Apomixis, a clonal plant reproduction by seeds, is controlled in Paspalum spp. by a single locus which is blocked in terms of recombination. Partial sequence analysis of the apomixis locus revealed structural features of heterochromatin, namely the presence of repetitive elements, gene degeneration, and de-regulation. To test the epigenetic control of apomixis, a study on the distribution of cytosine methylation at the apomixis locus and the effect of artificial DNA demethylation on the mode of reproduction was undertaken in two apomictic Paspalum species. The 5-methylcytosine distribution in the apomixis-controlling genomic region was studied in P. simplex by methylation-sensitive restriction fragment length polymorphism (RFLP) analysis and in P. notatum by fluorescene in situ hybridization (FISH). The effect of DNA demethylation was studied on the mode of reproduction of P. simplex by progeny test analysis of apomictic plants treated with the demethylating agent 5'-azacytidine. A high level of cytosine methylation was detected at the apomixis-controlling genomic region in both species. By analysing a total of 374 open pollination progeny, it was found that artificial demethylation had little or no effect on apospory, whereas it induced a significant depression of parthenogenesis. The results suggested that factors controlling repression of parthenogenesis might be inactivated in apomictic Paspalum by DNA methylation. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  14. Cytotype stability, facultative apomixis and geographical parthenogenesis in Ranunculus kuepferi (Ranunculaceae).

    Science.gov (United States)

    Cosendai, Anne-Caroline; Hörandl, Elvira

    2010-03-01

    Asexual organisms are more widespread in previously glaciated areas than their sexual relatives ('geographical parthenogenesis'). In plants, this pattern is probably dependent on reproductive isolation and stability of cytotypes within their respective distribution areas. Both partial apomixis and introgressive hybridization potentially destabilize the spatial separation of sexual and apomictic populations. The wide distribution of apomicts may be further enhanced by uniparental reproduction which is advantageous for colonization. These factors are studied in the alpine species Ranunculus kuepferi. Geographical distribution, diversity and mode of reproduction of cytotypes were assessed using flow cytometry and flow cytometric seed screening on samples from 59 natural populations of Ranunculus kuepferi. Seed set of cytotypes was compared in the wild. Diploid sexuals are confined to the south-western parts of the Alps, while tetraploid apomicts dominate in previously glaciated and in geographically isolated areas despite a significantly lower fertility. Other cytotypes (3x, 5x and 6x) occur mainly in the sympatric zone, but without establishing populations. The tetraploids are predominantly apomictic, but also show a partial apomixis via an uncoupling of apomeiosis and parthenogenesis in the seed material. Both pseudogamy and autonomous endosperm formation are observed which may enhance uniparental reproduction. Diploids occupy a glacial relic area and resist introgression of apomixis, probably because of a significantly higher seed set. Among the polyploids, only apomictic tetraploids form stable populations; the other cytotypes arising from partial apomixis fail to establish, probably because of minority cytotype disadvantages. Tetraploid apomicts colonize previously devastated and also distant areas via long-distance dispersal, confirming Baker's law of an advantage of uniparental reproduction. It is concluded that stability of cytotypes and of modes of

  15. Cytotype stability, facultative apomixis and geographical parthenogenesis in Ranunculus kuepferi (Ranunculaceae)

    Science.gov (United States)

    Cosendai, Anne-Caroline; Hörandl, Elvira

    2010-01-01

    Background and Aims Asexual organisms are more widespread in previously glaciated areas than their sexual relatives (‘geographical parthenogenesis’). In plants, this pattern is probably dependent on reproductive isolation and stability of cytotypes within their respective distribution areas. Both partial apomixis and introgressive hybridization potentially destabilize the spatial separation of sexual and apomictic populations. The wide distribution of apomicts may be further enhanced by uniparental reproduction which is advantageous for colonization. These factors are studied in the alpine species Ranunculus kuepferi. Methods Geographical distribution, diversity and mode of reproduction of cytotypes were assessed using flow cytometry and flow cytometric seed screening on samples from 59 natural populations of Ranunculus kuepferi. Seed set of cytotypes was compared in the wild. Key Results Diploid sexuals are confined to the south-western parts of the Alps, while tetraploid apomicts dominate in previously glaciated and in geographically isolated areas despite a significantly lower fertility. Other cytotypes (3x, 5x and 6x) occur mainly in the sympatric zone, but without establishing populations. The tetraploids are predominantly apomictic, but also show a partial apomixis via an uncoupling of apomeiosis and parthenogenesis in the seed material. Both pseudogamy and autonomous endosperm formation are observed which may enhance uniparental reproduction. Conclusions Diploids occupy a glacial relic area and resist introgression of apomixis, probably because of a significantly higher seed set. Among the polyploids, only apomictic tetraploids form stable populations; the other cytotypes arising from partial apomixis fail to establish, probably because of minority cytotype disadvantages. Tetraploid apomicts colonize previously devastated and also distant areas via long-distance dispersal, confirming Baker's law of an advantage of uniparental reproduction. It is

  16. Molecular cytogenetics and DNA sequence analysis of an apomixis-linked BAC in Paspalum simplex reveal a non pericentromere location and partial microcolinearity with rice

    NARCIS (Netherlands)

    Calderini, O.; Chang, S.B.; Jong, de J.H.S.G.M.; Busti, A.; Paolocci, F.; Arcioni, S.; Vries, de S.C.; Abma-Henkens, M.H.C.; Klein Lankhorst, R.M.; Donnison, I.S.; Pupilli, F.

    2006-01-01

    Apomixis in plants is a form of clonal reproduction through seeds. A BAC clone linked to apomictic reproduction in Paspalum simplex was used to locate the apomixis locus on meiotic chromosome preparations. Fluorescent in situ hybridisation revealed the existence of a single locus embedded in a

  17. Transient Activation of Apomixis in Sexual Neotriploids May Retain Genomically Altered States and Enhance Polyploid Establishment

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    Diego Hojsgaard

    2018-02-01

    Full Text Available Polyploid genomes evolve and follow a series of dynamic transfigurations along with adaptation and speciation. The initial formation of a new polyploid individual within a diploid population usually involves a triploid bridge, a two-step mechanism of cell fusions between ubiquitous (reduced and rare (unreduced gametes. The primary fusion event creates an intermediate triploid individual with unbalanced genome sets, a situation of genomic-shock characterized by gene expression dysregulation, high dosage sensitivity, disturbed cell divisions, and physiological and reproductive attributes drastically altered. This near-sterile neotriploid must produce (even eupolyploids through secondary fusion events to restore genome steadiness, meiotic balance, and fertility required for the demographic establishment of a nascent lineage. Natural conditions locate several difficulties to polyploid establishment, including the production of highly unbalanced and rarely unreduced (euploid gametes, frequency-dependent disadvantages (minority cytotype exclusion, severe fitness loss, and ecological competition with diploid parents. Persistence and adaptation of neopolyploids depend upon genetic and phenotypic novelty coupled to joint selective forces that preserve shock-induced genomic changes (subgenome homeolog partitioning and drive meiotic (reproductive stabilization and ecological diversification. Thus, polyploid establishment through the triploid bridge is a feasible but not ubiquitous process that requires a number of low-probability events and singular circumstances. Yet, frequencies of polyploids suggest that polyploid establishment is a pervasive process. To explain this disparity, and supported in experimental evidence, I propose that situations like hybridization and ploidy-state transitions associated to genomic shock and substantial developmental alterations can transiently activate apomixis as a mechanism to halt genomic instability and cancel factors

  18. Assembly of the Boechera retrofracta Genome and Evolutionary Analysis of Apomixis-Associated Genes

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    Sergei Kliver

    2018-03-01

    Full Text Available Closely related to the model plant Arabidopsis thaliana, the genus Boechera is known to contain both sexual and apomictic species or accessions. Boechera retrofracta is a diploid sexually reproducing species and is thought to be an ancestral parent species of apomictic species. Here we report the de novo assembly of the B. retrofracta genome using short Illumina and Roche reads from 1 paired-end and 3 mate pair libraries. The distribution of 23-mers from the paired end library has indicated a low level of heterozygosity and the presence of detectable duplications and triplications. The genome size was estimated to be equal 227 Mb. N50 of the assembled scaffolds was 2.3 Mb. Using a hybrid approach that combines homology-based and de novo methods 27,048 protein-coding genes were predicted. Also repeats, transfer RNA (tRNA and ribosomal RNA (rRNA genes were annotated. Finally, genes of B. retrofracta and 6 other Brassicaceae species were used for phylogenetic tree reconstruction. In addition, we explored the histidine exonuclease APOLLO locus, related to apomixis in Boechera, and proposed model of its evolution through the series of duplications. An assembled genome of B. retrofracta will help in the challenging assembly of the highly heterozygous genomes of hybrid apomictic species.

  19. Patterns of genetic variation in Pilosella echioides and its selected relatives: results of variation in ploidy level, facultative apomixis and past and present hybridization

    Czech Academy of Sciences Publication Activity Database

    Chrtek, Jindřich; Plačková, Ivana; Dočkalová, Zuzana; Krahulcová, Anna; Trávníček, Pavel

    2014-01-01

    Roč. 300, č. 9 (2014), s. 2091-2104 ISSN 0378-2697 R&D Projects: GA ČR GAP506/10/1363; GA ČR GP13-18610P Institutional support: RVO:67985939 Keywords : Pilosella * allozymes * apomixis Subject RIV: EF - Botanics Impact factor: 1.422, year: 2014

  20. Expressivity of apomixis in 2n + n hybrids from an apomictic and a sexual parent: insights into variation detected in Pilosella (Asteraceae: Lactuceae)

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Krahulec, František; Rosenbaumová, R.

    2011-01-01

    Roč. 24, č. 1 (2011), s. 263-274 ISSN 0934-0882 R&D Projects: GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Keywords : inheritance of apomixis * residual sexuality * unreduced hybrids Subject RIV: EF - Botanics Impact factor: 1.869, year: 2011

  1. In Silico and Fluorescence In Situ Hybridization Mapping Reveals Collinearity between the Pennisetum squamulatum Apomixis Carrier-Chromosome and Chromosome 2 of Sorghum and Foxtail Millet.

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    Sirjan Sapkota

    Full Text Available Apomixis, or clonal propagation through seed, is a trait identified within multiple species of the grass family (Poaceae. The genetic locus controlling apomixis in Pennisetum squamulatum (syn Cenchrus squamulatus and Cenchrus ciliaris (syn Pennisetum ciliare, buffelgrass is the apospory-specific genomic region (ASGR. Previously, the ASGR was shown to be highly conserved but inverted in marker order between P. squamulatum and C. ciliaris based on fluorescence in situ hybridization (FISH and varied in both karyotype and position of the ASGR on the ASGR-carrier chromosome among other apomictic Cenchrus/Pennisetum species. Using in silico transcript mapping and verification of physical positions of some of the transcripts via FISH, we discovered that the ASGR-carrier chromosome from P. squamulatum is collinear with chromosome 2 of foxtail millet and sorghum outside of the ASGR. The in silico ordering of the ASGR-carrier chromosome markers, previously unmapped in P. squamulatum, allowed for the identification of a backcross line with structural changes to the P. squamulatum ASGR-carrier chromosome derived from gamma irradiated pollen.

  2. In Silico and Fluorescence In Situ Hybridization Mapping Reveals Collinearity between the Pennisetum squamulatum Apomixis Carrier-Chromosome and Chromosome 2 of Sorghum and Foxtail Millet.

    Science.gov (United States)

    Sapkota, Sirjan; Conner, Joann A; Hanna, Wayne W; Simon, Bindu; Fengler, Kevin; Deschamps, Stéphane; Cigan, Mark; Ozias-Akins, Peggy

    2016-01-01

    Apomixis, or clonal propagation through seed, is a trait identified within multiple species of the grass family (Poaceae). The genetic locus controlling apomixis in Pennisetum squamulatum (syn Cenchrus squamulatus) and Cenchrus ciliaris (syn Pennisetum ciliare, buffelgrass) is the apospory-specific genomic region (ASGR). Previously, the ASGR was shown to be highly conserved but inverted in marker order between P. squamulatum and C. ciliaris based on fluorescence in situ hybridization (FISH) and varied in both karyotype and position of the ASGR on the ASGR-carrier chromosome among other apomictic Cenchrus/Pennisetum species. Using in silico transcript mapping and verification of physical positions of some of the transcripts via FISH, we discovered that the ASGR-carrier chromosome from P. squamulatum is collinear with chromosome 2 of foxtail millet and sorghum outside of the ASGR. The in silico ordering of the ASGR-carrier chromosome markers, previously unmapped in P. squamulatum, allowed for the identification of a backcross line with structural changes to the P. squamulatum ASGR-carrier chromosome derived from gamma irradiated pollen.

  3. Apomixia em Manihot esculenta e em seus híbridos interespecíficos Apomixis in Manihot esculenta and in its interespecific hybrids

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    Evie dos Santos de Sousa

    2001-09-01

    Full Text Available O objetivo deste trabalho foi estudar a citogenética e a morfologia do saco embrionário dos clones EB1 (Manihot esculenta Crantz e EB12 (geração F3 de M. esculenta x M. glaziovii Muell, dos híbridos F1 e F2 de M. neusana Nassar x M. esculenta e da espécie silvestre M. neusana, para verificar o fenômeno da apomixia. Os óvulos foram analisados pelo método de clarificação. Foi verificada apomixia, do tipo apospórica, no clone EB12, no híbrido F2, e em M. neusana. Foi demonstrada a estrutura embriônica da mandioca; foram observados dois sacos embrionários no mesmo óvulo do híbrido F2.The objective of this work was to study cytogenetic and morphology of the embryonic sac of clones EB1 (Manihot esculenta Crantz and EB12 (F3of M. esculenta x M. glaziovii Muell, of F1 and F2 hybrids of M. neusana Nassar x M. esculenta and of the wild species M. neusana, to verify the phenomenon of apomixis. Ovules were observed by the clarification method. Aposporic apomixis was observed in the EB12 clone, in the F2 hybrid and in M. neusana. The embryonic structure of Manihot was demonstrated and two embryonic sac were observed in the same ovule of F2.

  4. Female parthenogenetic apomixis and androsporogenetic parthenogenesis in embryonal cells of Araucaria angustifolia: interpolation of progenesis and asexual heterospory in an artificial sporangium.

    Science.gov (United States)

    Durzan, Don J

    2012-09-01

    Cell fate, development timing and occurrence of reproductive versus apomictic development in gymnosperms are shown to be influenced by culture conditions in vitro. In this study, female parthenogenetic apomixis (fPA), androsporogenetic parthenogenesis (mAP) and progenesis were demonstrated using embryonal initials of Araucaria angustifolia in scaled-up cell suspensions passing through a single-cell bottleneck in darkness and in an artificial sporangium (AS). Expression was based on defined nutrition, hormones and feedforward-adaptive feedback process controls at 23-25 °C and in darkness. In fPA, the nucleus of an embryonal initial undergoes endomitosis and amitosis, forming a diploid egg-equivalent and an apoptotic ventral canal nucleus in a transdifferentiated archegonial tube. Discharge of egg-equivalent cells as parthenospores and their dispersal into the aqueous culture medium were followed by free-nuclear conifer-type proembryogenesis. This replaced the plesiomorphic and central features of proembryogenesis in Araucariaceae. Protoplasmic fusions of embryonal initials were used to reconstruct heterokaryotic expressions of fPA in multiwell plates. In mAP, restitutional meiosis (automixis) was responsible for androsporogenesis and the discharge of monads, dyads, tetrads and polyads. In a display of progenesis, reproductive development was brought to an earlier ontogenetic stage and expressed by embryonal initials. Colchicine increased polyploidy, but androspore formation became aberrant and fragmented. Aberrant automixis led to the formation of chromosomal bouquets, which contributed to genomic silencing in embryonal initials, cytomixis and the formation of pycnotic micronucleated cells. Dispersal of female and male parthenospores displayed heteromorphic asexual heterospory in an aqueous environment.

  5. Modes of inheritance of two apomixis components, diplospory and parthenogenesis, in Chinese chive (Allium ramosum) revealed by analysis of the segregating population generated by back-crossing between amphimictic and apomictic diploids

    Science.gov (United States)

    Yamashita, Ken-ichiro; Nakazawa, Yoshiko; Namai, Kiyoshi; Amagai, Masayuki; Tsukazaki, Hikaru; Wako, Tadayuki; Kojima, Akio

    2012-01-01

    To investigate the mode of inheritance of apomixis in Chinese chive, the degrees of diplospory and parthenogenesis were evaluated in F1 and BC1 progenies derived from crosses between amphimictic and apomictic diploids (2n = 16, 2x). The F1 population was generated by crossing three amphimictic diploids 94Mo13, 94Mo49 and 94Mo50 with an apomictic diploid KaD2 and comprised 110 diploids and 773 triploids. All the diploid F1 plants examined were completely or highly eusporous and completely syngamic. All the triploid F1 plants examined were highly diplosporous and highly parthenogenetic. KaD2 could not transmit its high level of apomixis via monoploid pollen grains. The BC1 population, generated by crossing 94Mo49 with apomictic triploids found in the F1 offspring, exhibited heteroploidy; it comprised haploid, diploid, triploid, tetraploid and various aneuploid individuals. In this generation, clear segregation was observed between diplospory and parthenogenesis. Analysis of the BC1 population suggests that diplospory and parthenogenesis are each controlled by single dominant genes, D and P, respectively. However, all the BC1 plants characterized as parthenogenetic were diplosporous. The absence of phenotypically eusporous parthenogenetic plants can be explained by assuming that the presence of diplospory gene is a prerequisite for the parthenogenesis gene expression in Chinese chive. PMID:23136527

  6. Molecular markers linked to apomixis in Panicum maximum Jacq.

    African Journals Online (AJOL)

    SAM

    2014-05-28

    May 28, 2014 ... Panicum maximum Jacq. is an important forage grass of African origin largely used in the tropics. The genetic breeding of this ... Pastures play an important role in the national economy of most countries in the tropics .... final volume of 25 µL, using, 1xTaq DNA polymerase buffer. (Invitrogen); 1.5 mM MgCl2.

  7. Identification of apomixis in the Kentucky bluegrass (Poa pratensis L. using auxin test

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    Janetta Niemann

    2012-08-01

    Full Text Available The effect of auxin treatment on the formation of apomictic – endospermless grains in Poa pratensis was investigated in the study. Four Polish cultivars: Skiz, Eska 46, Alicja, Ani as well as six breeding lines: POB 13, SK-W-33, SKW-15, SKW-35A, SK-W-35A and SK-W-35B were tested by embryological methods to reveal the reproduction pathway in greenhouse and field conditions. The obtained results showed that four genotypes, i.e. Alicja, Ani, Eska 46 and SK-W-35B are facultative apomictic and the other have formed seeds only on the apomictic way. In facultative apomicts it was found that in many cases both endospermless ovules containing embryo sacs with embryos or embryo sacs with well developed endosperm were formed. In the case of apomictic genotypes only endospermless seeds were observed.

  8. Apomixis and the problem of obtaining haploids and homozygote diploids in pear (Pyrus communis L.

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    Є. О. Долматов

    2013-02-01

    Full Text Available The article highlights results of research over simulative apomixes in pear and its utilization for obtaining haploids and homozygote diploids. It has been established that over 50% pear varieties with failed remote hybridization are capable of generating seeds of apomictic origin producing diploid plants. Genotypes displaying maximal inclination to apomixes have been singled out. Apomictic pear seedlings obtained from foreign pollination within the limits of the same combination are inherent in profound morphological diversity. Fruit-bearing apomicts originated from one and the same maternal plant differ to the same extent as hybrid seedlings of the same family. Genetic markers have enabled to establish that these are embryo sacs in which meiosis has completed that give rise to apomictic seeds. In vitro method as used for the purpose of increasing apomictic plants output has been illustrated. The greatest induction of apomictic shoots in vitro has been reached by alternation of BAP cytokinin at concentration of 1mg/l and 2 mg/l on the background of GA3 amounting to 1,5 mg/l. Grafting with shoots in vitro on non-sterile rootstocks of pear (Pyrus communis has increased the output of plants up to 80%. A cytological assessment of 9 apomictic samples is provided. The cytological analysis of samples of apomictic forms has certified the presence of simulative haploid parthenogenesis in pear.

  9. Complex Interspecific Hybridization in Barley (Hordeum vulgare L.) and the Possible Occurrence of Apomixis

    DEFF Research Database (Denmark)

    Bothmer, R. von; Bengtsson, M.; Flink, J.

    1988-01-01

    mixoploid with respect to alien chromosomes (19-22). In one combination, chromosome no. 7 was duplicated. Meiosis in triple hybrids showed low, but variable pairing (1.3-5.5 chiasmata per cell). The syndesis probably did not include the barley chromosomes. Direct backcrosses to di- and tetraploid......-chromosomic plant in which the male parental genome was absent. We suspect that this plant may have arisen through parthenogenetic development of a reduced female gemete. The other cross with a diploid line ('9208/9') resulted in plant with 2n = 51-53. The most likely explanation for this second plant...... is that an unreduced gamete from the amphiploid was fertilized by a normal gamete from the backcross parent, and during early embryo development, some chromosomes were eliminated....

  10. Desynapsis and FDR 2N-megaspore formation in diploid potato : potentials and limitations for breeding and for the induction of diplosporic apomixis

    NARCIS (Netherlands)

    Jongedijk, E.

    1991-01-01

    The cultivated potato, Solanum tuberosum L., is a highly heterozygous autotetraploid (2n=4x=48) plant species, which after its introduction into Europe in the 16th century has become one of the world's major food crops. The potato has traditionally been grown from

  11. Viewpoints on apornictic and sexual reproduction in angiosperms

    Directory of Open Access Journals (Sweden)

    Sven Asker

    2014-01-01

    Full Text Available Gametophytic apomixis implies different changes of the reproductive cycle of sexual plants. Each of these "elements of apomixis" occurs in sexual plants, which may even display functional diploid parthenogenesis. Thus, apomixis, like vegetative reproduction, is part of the reproductive behaviour of sexual plants, becoming important when sexual reproduction is impaired. The elements of apomixis are probably to a large extent under polygenic control.

  12. Quantitative variation for apomictic reproduction in the genus Boechera (Brassicaceae)

    NARCIS (Netherlands)

    Aliyu, O.M.; Schranz, M.E.; Sharbel, T.F.

    2010-01-01

    • Premise of the study: The evolution of asexual seed production (apomixis) from sexual relatives is a great enigma of plant biology. The genus Boechera is ideal for studying apomixis because of its close relation to Arabidopsis and the occurrence of sexual and apomictic species at low ploidy levels

  13. Reproduction - a factor of plant evolution

    Directory of Open Access Journals (Sweden)

    Ion I. Bǎra

    2014-01-01

    Full Text Available The process of reproduction (amphimixis and apomixis represents a major factor of evolution. The facultative apomictic species are the pioneers of evolution. They combine the adventages of amphimixis (high degree of variability and heterogenesis and apomixis (relative stability and low material expenditure assuring a rapid rate of adaptive evolution.

  14. How apomictic taxa are treated in current taxonomy: A review

    Czech Academy of Sciences Publication Activity Database

    Majeský, L.; Krahulec, František; Vašut, R.J.

    2017-01-01

    Roč. 66, č. 5 (2017), s. 1017-1040 ISSN 0040-0262 Institutional support: RVO:67985939 Keywords : apomixis * hybridization * species concept Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.447, year: 2016

  15. Natural epigenetic variation contributes to heritable flowering divergence in a widespread asexual dandelion lineage

    Czech Academy of Sciences Publication Activity Database

    Wilschut, R. A.; Oplaat, C.; Snoek, L. B.; Kirschner, Jan; Verhoeven, K. J. F.

    2016-01-01

    Roč. 25, č. 8 (2016), s. 1759-1768 ISSN 0962-1083 Institutional support: RVO:67985939 Keywords : apomixis * epigenetics * Taraxacum Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.086, year: 2016

  16. Estimating paternal efficiency in an agamic polyploid complex: pollen stainability and variation in pollen size related to reproduction mode, ploidy level and hybridogenous origin in Pilosella (Asteraceae)

    Czech Academy of Sciences Publication Activity Database

    Rotreklová, O.; Krahulcová, Anna

    2016-01-01

    Roč. 51, č. 2 (2016), s. 175-186 ISSN 1211-9520 Institutional support: RVO:67985939 Keywords : autonomous apomixis * effect of pollen parent * hybridization Subject RIV: EF - Botanics Impact factor: 1.017, year: 2016

  17. Ploidy level selection during germination and early stage of seedling growth in the progeny of allohexaploid facultative apomict, Hieracium rubrum (Asteraceae)

    Czech Academy of Sciences Publication Activity Database

    Krahulec, František; Krahulcová, Anna; Papoušková, S.

    2006-01-01

    Roč. 41, - (2006), s. 407-416 ISSN 1211-9520 R&D Projects: GA AV ČR IAA6005203 Institutional research plan: CEZ:AV0Z60050516 Keywords : facultative apomixis * hybrids * polyhaploids Subject RIV: EF - Botanics Impact factor: 1.196, year: 2006

  18. Development of innovative techniques and principles that may be used as models to improve plant performance. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, Wayne W.; Burton, Glenn W.

    2000-06-25

    We developed fundamental methods and techniques for transferring germplasm from wild to cultivated species. Germplasm transferred included diverse cytoplasms, new genes for pest resistance, genes controlling dry matter yield and apomixis. Some of the germplasm has been shown to be valuable in plant breeding and has been incorporated into commercial cultivators.

  19. A genetic linkage map of the diplosporous chromosomal region in Taraxacum officinale (common dandelion; Asteracaea)

    NARCIS (Netherlands)

    Vijverberg, K.; Hulst, van der R.G.M.; Lindhout, W.H.; Dijk, P.J.

    2004-01-01

    In this study, we mapped the diplosporous chromosomal region in Taraxacum officinale, by using amplified fragment length polymorphism technology (AFLP) in 73 plants from a segregating population. Taraxacum serves as a model system to investigate the genetics, ecology, and evolution of apomixis. The

  20. A genetic linkage map of the diplosporous chromosomal region in Taraxacum officinale (common dandelion; Asteraceae)

    NARCIS (Netherlands)

    Vijverberg, Kitty; van der Hulst, R.G.M.; Lindhout, P.; Van Dijk, P.J.

    2004-01-01

    In this study, we mapped the diplosporous chromosomal region in Taraxacum officinale, by using amplified fragment length polymorphism technology (AFLP) in 73 plants from a segregating population. Taraxacum serves as a model system to investigate the genetics, ecology, and evolution of apomixis. The

  1. Development and characterization of nine new microsatellite markers in Taraxacum (Asteraceae).

    NARCIS (Netherlands)

    Vasut, R.; Dijk, P.J.; Falque, M.; Trávnicek, B.; Jong, de J.H.S.G.M.

    2004-01-01

    This study aims at developing and characterizing new microsatellite primer pairs in Taraxacum officinale auct. to produce polymorphic markers for genetical and evolutionary studies on apomixis in this sexual-apomictic complex. A total of 24 diploid plants were tested for allelic polymorphism and

  2. Chromosome studies and genetic analysis of natural and synthetic apomictic model species

    NARCIS (Netherlands)

    Kantama, L.

    2005-01-01

    Some plants have gained the ability to produce seed without fertilisation. This alternative to sexual reproduction, known as apomixis occurs most frequently in species of the families of the grasses, roses and composites, and mostly in polyploids and is considered one of the ways to escape from

  3. Chromosome numbers and meiotic analysis in the pre-breeding of ...

    Indian Academy of Sciences (India)

    2011-08-19

    Aug 19, 2011 ... Seixas M. A. C. and Esteves A. 2000 Determinação de poli- ploidia e avaliação da quantidade de DNA total em diferentes espécies de gênero Brachiaria. Boletim de Pesquisa 11, Embrapa. Gado de Corte, Campo Grande, MS, Brazil. Pritchard A. J. 1967 Apomixis in Brachiaria decumbens Stapf. J. Aust.

  4. Use of the SSLP-based method for detection of rare apomictic events in a sexual AtSERK1 transgenic Arabidopsis population

    NARCIS (Netherlands)

    Kantama, L.; Lambert, J.M.; Hu, H.; Jong, de H.; Vries, de S.C.; Russinova, E.

    2006-01-01

    Here we present a screening method to evaluate the potential of genes to transfer aspects of apomixis into sexual crop plants. Based on the assumption that an apomictic progeny is an exact genetic replica of the mother plant we employed a set of single sequence length polymorphism (SSLP) markers to

  5. Sex expression and breeding strategy in Commelina benghalensis L.

    Indian Academy of Sciences (India)

    Prakash

    2009-12-03

    Dec 3, 2009 ... [Kaul V and Koul A K 2009 Sex expression and breeding strategy in Commelina benghalensis L.; J. Biosci. 34 977–990]. DOI 10.1007/s12038-009-0112-5. Keywords. Chasmogamous; cleistogamous; reproductive output; sex expression. Abbreviations used: A, autogamy; AP, apomixis; CH, chasmogamous ...

  6. Taxonomic revision of Sorbus subgenus Aria occurring in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Lepší, M.; Lepší, P.; Koutecký, P.; Bílá, J.; Vít, Petr

    2015-01-01

    Roč. 87, č. 2 (2015), s. 109-162 ISSN 0032-7786 R&D Projects: GA ČR GB14-36079G Institutional support: RVO:67985939 Keywords : apomixis * DAPI flow cytometry * hybridization Subject RIV: EF - Botanics Impact factor: 2.711, year: 2015

  7. Production of polyhaploids by facultatively apomictic Pilosella can result in formation of new genotypes via genome doubling

    Czech Academy of Sciences Publication Activity Database

    Krahulec, František; Krahulcová, Anna; Rosenbaumová, R.; Plačková, Ivana

    2011-01-01

    Roč. 83, č. 3 (2011), s. 471-490 ISSN 0032-7786 R&D Projects: GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Keywords : polyploid-polyhaploid-polyploid cycle * apomixis * genome doubling Subject RIV: EF - Botanics Impact factor: 2.521, year: 2011

  8. Journal of Biosciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Biosciences; Volume 33; Issue 3. Issue front cover thumbnail. Volume 33, Issue 3. September 2008, pages 309-421. pp 309-311. Clipboard: Functional embryo sac formation in Arabidopsis without meiosis – one step towards asexual seed formation (apomixis) in crops? Anna M G Koltunow ...

  9. The Red Queen hypothesis and geographical parthenogenesis in the alpine hawkweed Hieracium alpinum (Asteraceae)

    Czech Academy of Sciences Publication Activity Database

    Hartmann, M.; Štefánek, M.; Zdvořák, P.; Heřman, P.; Chrtek, Jindřich; Mráz, P.

    2017-01-01

    Roč. 122, č. 4 (2017), s. 681-696 ISSN 0024-4066 Institutional support: RVO:67985939 Keywords : apomixis * polyploidy * Red Queen hypothesis Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.288, year: 2016

  10. Is the aneuploid chromosome in an apomictic Boechera holboellii a genuine B chromosome?

    NARCIS (Netherlands)

    Sharbel, T.F.; Voigt, M.L.; Mitchell-Olds, T.; Kantama, L.; Jong, de J.H.S.G.M.

    2004-01-01

    The Boechera holboellii complex comprises B. holboellii and B. drummondii, both of which can reproduce through sex or apomixis. Sexuality is associated with diploidy, whereas apomictic individuals can either be diploid, aneuploid or triploid. Aneuploid individuals are found in geographically and

  11. Hieracium caespitosum and Hieracium piloselloides (Asteraceae) in the Black Hills National Forest: New state records for South Dakota, U.S.A

    Science.gov (United States)

    Brian E. Dickerson; Cheryl Mayer; Justin Ramsey; Zach Mergen; Mark Gabel

    2016-01-01

    Hieracium spp. (Asteraceae) are noted for their taxonomic complexity, frequent incidence of apomixis and polyploidy, and invasive tendencies. Here we report the Eurasian taxa, Hieracium caespitosum Dumort. and Hieracium piloselloides Vill., as recent additions to the flora of South Dakota. Plants were collected at three locations in the Black Hills during 2014 and 2015...

  12. The detection, rate and manifestation of residual sexuality in apomictic populations of Pilosella (Asteraceae, Lactuceae)

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Rotreklová, O.; Krahulec, František

    2014-01-01

    Roč. 49, č. 2 (2014), s. 239-258 ISSN 1211-9520 R&D Projects: GA ČR GAP506/10/1363 Institutional support: RVO:67985939 Keywords : facultative apomixis * haploid parthenogenesis * interspecific hybridization * Pilosella * residual sexuality Subject RIV: EF - Botanics Impact factor: 1.778, year: 2014

  13. A modified method of flow cytometric seed screen simplifies the quantification of progeny classes with different ploidy levels

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Suda, Jan

    2006-01-01

    Roč. 50, č. 3 (2006), s. 457-460 ISSN 0006-3134 R&D Projects: GA AV ČR IAA6005203 Institutional research plan: CEZ:AV0Z60050516 Keywords : facultative apomixis * reproduction routes * polyhaploids Subject RIV: EF - Botanics Impact factor: 1.198, year: 2006

  14. The intriguing complexity of parthenogenesis inheritance in Pilosella rubra (Asteraceae, Lactuceae)

    Czech Academy of Sciences Publication Activity Database

    Rosenbaumová, R.; Krahulcová, Anna; Krahulec, František

    2012-01-01

    Roč. 25, č. 3 (2012), s. 185-196 ISSN 0934-0882 R&D Projects: GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Institutional support: RVO:67985939 Keywords : apomixis * inheritance of parthenogenesis * haploid parthenogenesis Subject RIV: EF - Botanics Impact factor: 2.070, year: 2012

  15. Genetic variation in the Hieracium rohacsense group (Hieracium sect. Alpina)

    Czech Academy of Sciences Publication Activity Database

    Mráz, P.; Chrtek, Jindřich; Kirschner, Jan

    2001-01-01

    Roč. 41, č. 2 (2001), s. 269-276 ISSN 0079-2047 R&D Projects: GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z6005908 Keywords : Asteraceae, Compositae, Hieracium * Apomixis, isozymes * Flora of the Carpathians Subject RIV: EF - Botanics Impact factor: 0.275, year: 2001

  16. Geographical parthenogenesis, genome size variation and pollen production in the arctic-alpine species Hieracium alpinum

    Czech Academy of Sciences Publication Activity Database

    Mráz, P.; Chrtek, Jindřich; Šingliarová, B.

    2009-01-01

    Roč. 119, č. 1 (2009), s. 41-51 ISSN 0253-1453 R&D Projects: GA ČR GA206/05/0657 Institutional research plan: CEZ:AV0Z60050516 Keywords : apomixis * Compositae * polyploidy Subject RIV: EF - Botanics Impact factor: 0.900, year: 2009

  17. Ploidy determination of buffel grass accessions in the USDA National Plant Germplasm System collection by flow cytometry

    Science.gov (United States)

    Buffelgrass [Pennisetum ciliare (L.) Link syn. Cenchrus ciliaris L.] is an important forage and range grass in many of the semi-arid tropical and subtropical regions of the world. The species reproduces primarily by apomixis but it is highly diverse because a wide array of different apomictic ecoty...

  18. Genetic diversity among pentaploid buffelgrass accessions

    Science.gov (United States)

    Buffelgrass (Pennisetum ciliare) is an important range and pasture grass that grows in the arid tropics and semi-tropics. It has excellent drought tolerance but lacks winter hardiness. Even though the grass reproduces primarily by apomixis, it is highly polymorphic. A range of chromosome numbers ...

  19. Sexual and apomictic reproduction in Hieracium sub genus Pilosella are closely interrelated developmental pathways

    NARCIS (Netherlands)

    Tucker, M.R.; Araujo, A.C.G.; Paech, N.A.; Hecht, V.; Schmidt, E.D.L.; Rossel, J.B.; Vries, de S.C.; Koltunow, A.M.

    2003-01-01

    Seed formation in flowering plants requires meiosis of the megaspore mother cell (MMC) inside the ovule, selection of a megaspore that undergoes mitosis to form an embryo sad, and double fertilization to initiate embryo and endosperm formation. During apomixis, or asexual seed formation, in

  20. Apomictic parthenogenesis in a parasitoid wasp Meteorus pulchricornis, uncommon in the haplodiploid order Hymenoptera.

    Science.gov (United States)

    Tsutsui, Y; Maeto, K; Hamaguchi, K; Isaki, Y; Takami, Y; Naito, T; Miura, K

    2014-06-01

    Although apomixis is the most common form of parthenogenesis in diplodiploid arthropods, it is uncommon in the haplodiploid insect order Hymenoptera. We found a new type of spontaneous apomixis in the Hymenoptera, completely lacking meiosis and the expulsion of polar bodies in egg maturation division, on the thelytokous strain of a parasitoid wasp Meteorus pulchricornis (Wesmael) (Braconidae, Euphorinae) on pest lepidopteran larvae Spodoptera litura (Fabricius) (Noctuidae). The absence of the meiotic process was consistent with a non-segregation pattern in the offspring of heterozygous females, and no positive evidence was obtained for the induction of thelytoky by any bacterial symbionts. We discuss the conditions that enable the occurrence of such rare cases of apomictic thelytoky in the Hymenoptera, suggesting the significance of fixed heterosis caused by hybridization or polyploidization, symbiosis with bacterial agents, and occasional sex. Our finding will encourage further genetic studies on parasitoid wasps to use asexual lines more wisely for biological control.

  1. Turning rice meiosis into mitosis.

    Science.gov (United States)

    Mieulet, Delphine; Jolivet, Sylvie; Rivard, Maud; Cromer, Laurence; Vernet, Aurore; Mayonove, Pauline; Pereira, Lucie; Droc, Gaëtan; Courtois, Brigitte; Guiderdoni, Emmanuel; Mercier, Raphael

    2016-11-01

    Introduction of clonal reproduction through seeds (apomixis) in crops has the potential to revolutionize agriculture by allowing self-propagation of any elite variety, in particular F1 hybrids. In the sexual model plant Arabidopsis thaliana synthetic clonal reproduction through seeds can be artificially implemented by (i) combining three mutations to turn meiosis into mitosis (MiMe) and (ii) crossing the obtained clonal gametes with a line expressing modified CENH3 and whose genome is eliminated in the zygote. Here we show that additional combinations of mutations can turn Arabidopsis meiosis into mitosis and that a combination of three mutations in rice (Oryza sativa) efficiently turns meiosis into mitosis, leading to the production of male and female clonal diploid gametes in this major crop. Successful implementation of the MiMe technology in the phylogenetically distant eudicot Arabidopsis and monocot rice opens doors for its application to any flowering plant and paves the way for introducing apomixis in crop species.

  2. Niche dynamics of alien species do not differ among sexual and apomictic flowering plants

    Czech Academy of Sciences Publication Activity Database

    Dellinger, A. S.; Essl, F.; Hojsgaard, D.; Kirchheimer, B.; Klatt, S.; Dawson, W.; Pergl, Jan; Pyšek, Petr; van Kleunen, M.; Weber, E.; Winter, M.; Hörandl, E.; Dullinger, S.

    2016-01-01

    Roč. 209, č. 3 (2016), s. 1313-1323 ISSN 0028-646X R&D Projects: GA ČR GB14-36079G Grant - others:AV ČR(CZ) AP1002 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:67985939 Keywords : invasions * GloNAF * apomixis Subject RIV: EF - Botanics Impact factor: 7.330, year: 2016

  3. Enriching ploidy level diversity: the role of apomictic and sexual biotypes of Hieracium subgen. Pilosella (Asteraceae) that coexist in polyploid populations

    Czech Academy of Sciences Publication Activity Database

    Krahulcová, Anna; Rotreklová, O.; Krahulec, František; Rosenbaumová, Radka; Plačková, Ivana

    2009-01-01

    Roč. 44, č. 3 (2009), s. 281-306 ISSN 1211-9520 R&D Projects: GA ČR GA206/07/0059; GA ČR GA206/08/0890 Institutional research plan: CEZ:AV0Z60050516 Keywords : facultative apomixis * genome instability * hybrid swarms * residual sexuality * unreduced gametes Subject RIV: EF - Botanics Impact factor: 1.320, year: 2009

  4. A genetic linkage map of the diplosporous chromosomal region in Taraxacum officinale (common dandelion; Asteraceae).

    Science.gov (United States)

    Vijverberg, K; Van Der Hulst, R G M; Lindhout, P; Van Dijk, P J

    2004-02-01

    In this study, we mapped the diplosporous chromosomal region in Taraxacum officinale, by using amplified fragment length polymorphism technology (AFLP) in 73 plants from a segregating population. Taraxacum serves as a model system to investigate the genetics, ecology, and evolution of apomixis. The genus includes sexual diploid as well as apomictic polyploid, mostly triploid, plants. Apomictic Taraxacum is diplosporous, parthenogenetic, and has autonomous endosperm formation. Previous studies have indicated that these three apomixis elements are controlled by more than one locus in Taraxacum and that diplospory inherits as a dominant, monogenic trait ( Ddd; DIP). A bulked segregant analysis provided 34 AFLP markers that were linked to DIP and were, together with two microsatellite markers, used for mapping the trait. The map length was 18.6 cM and markers were found on both sides of DIP, corresponding to 5.9 and 12.7 cM, respectively. None of the markers completely co-segregated with DIP. Eight markers were selected for PCR-based marker development, of which two were successfully converted. In contrast to all other mapping studies of apomeiosis to date, our results showed no evidence for suppression of recombination around the DIP locus in Taraxacum. No obvious evidence for sequence divergence between the DIP and non- DIP homologous loci was found, and no hemizygosity at the DIP locus was detected. These results may indicate that apomixis is relatively recent in Taraxacum.

  5. Polyembryony in Melastomataceae from Brazilian Cerrado: multiple embryos in a small world.

    Science.gov (United States)

    Mendes-Rodrigues, C; Oliveira, P E

    2012-09-01

    Polyembryony has been commonly associated with apomixis in the angiosperms and seems to be more common than expected, even in biomes where sexual reproduction processes are predominant. Recent studies in Cerrado, the Neotropical savannas of Central Brazil, showed high frequencies of apomixis and polyembryony and indicated these processes as reproductive and evolutionary alternatives for plants in these areas. In this sense, we investigated the occurrence of polyembryony and its relationships with ecological (season and type of dispersal, ploidy, species distribution and breeding system) and taxonomic (tribe) factors in the Melastomataceae, a mostly tropical family already known for its high frequency of apomixis and very common in Cerrado. We collected seeds from 69 populations of 53 species, which were sown in germination chambers. After seed germination, the presence and number of seedlings per seed were evaluated as a method to estimate polyembryony. We encountered 18 species (33.96%) with polyembryony (more than one seedling, or gemellar seedlings, originated per seed) concentrated in species of the tribe Miconieae (64%) and Microlicieae (16.67%), but absent in Melastomeae. Monoembryony was present only in sexual species, while all apomictic species were polyembryonic. In Miconia, the polyembryony was correlated with polyploidy, and monoembryony with diploid species. Polyembryony was more common among species with wide distribution in the Cerrado region, which indicates that the presence of gemellar seedlings is important for establishment and survival of the group in the Cerrado biome. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

  6. Population genetic structure of diploid sexual and polyploid apomictic hawthorns (Crataegus; Rosaceae) in the Pacific Northwest.

    Science.gov (United States)

    Lo, Eugenia Y Y; Stefanović, Sasa; Dickinson, Timothy A

    2009-03-01

    Polyploidy and gametophytic apomixis are two important and associated processes in plants. Many hawthorn species are polyploids and can reproduce both sexually and apomictically. However, the population genetic structure of these species is poorly understood. Crataegus douglasii is represented exclusively by self-compatible tetraploid pseudogamous apomicts across North America, whereas Crataegus suksdorfii found in the Pacific Northwest is known to include self-incompatible diploid sexuals as well as polyploid apomicts. We compare population structure and genetic variability in these two closely related taxa using microsatellite and chloroplast sequence markers. Using 13 microsatellite loci located on four linkage groups, 251 alleles were detected in 239 individuals sampled from 15 localities. Within-population multilocus genotypic variation and molecular diversity are greatest in diploid sexuals and lowest in triploid apomicts. Apart from the isolation of eastern North American populations of C. douglasii, there is little evidence of isolation by distance in this taxon. Genetic diversity in western populations of C. douglasii suggests that gene flow is frequent, and that colonization and establishment are often successful. In contrast, local populations of C. suksdorfii are more markedly differentiated. Gene flow appears to be limited primarily by distance in diploids and by apomixis and self-compatibility in polyploids. We infer that apomixis and reproductive barriers between cytotypes are factors that reduce the frequency of gene flow among populations, and may ultimately lead to allopatric speciation in C. suksdorfii. Our findings shed light on evolution in woody plants that show heterogeneous ploidy levels and reproductive systems.

  7. The intriguing complexity of parthenogenesis inheritance in Pilosella rubra (Asteraceae, Lactuceae).

    Science.gov (United States)

    Rosenbaumová, Radka; Krahulcová, Anna; Krahulec, František

    2012-09-01

    Neither the genetic basis nor the inheritance of apomixis is fully understood in plants. The present study is focused on the inheritance of parthenogenesis, one of the basic elements of apomixis, in Pilosella (Asteraceae). A complex pattern of inheritance was recorded in the segregating F(1) progeny recovered from reciprocal crosses between the facultatively apomictic hexaploid P. rubra and the sexual tetraploid P. officinarum. Although both female and male reduced gametes of P. rubra transmitted parthenogenesis at the same rate in the reciprocal crosses, the resulting segregating F(1) progeny inherited parthenogenesis at different rates. The actual transmission rates of parthenogenesis were significantly correlated with the mode of origin of the respective F(1) progeny class. The inheritance of parthenogenesis was significantly reduced in F(1) n + n hybrid progeny from the cross where parthenogenesis was transmitted by female gametes. In F(1) n + 0 polyhaploid progeny from the same cross, however, the transmission rate of parthenogenesis was high; all fertile polyhaploids were parthenogenetic. It appeared that reduced female gametes transmitting parthenogenesis preferentially developed parthenogenetically and only rarely were fertilized in P. rubra. The fact that the determinant for parthenogenesis acts gametophytically in Pilosella and the precocious embryogenesis in parthenogenesis-transmitting megagametophytes was suggested as the most probable explanations for this observation. Furthermore, we observed the different expression of complete apomixis in the non-segregating F(1) 2n + n hybrids as compared to their apomictic maternal parent P. rubra. We suggest that this difference is a result of unspecified interactions between the parental genomes.

  8. A parthenogenesis gene of apomict origin elicits embryo formation from unfertilized eggs in a sexual plant.

    Science.gov (United States)

    Conner, Joann A; Mookkan, Muruganantham; Huo, Heqiang; Chae, Keun; Ozias-Akins, Peggy

    2015-09-08

    Apomixis is a naturally occurring mode of asexual reproduction in flowering plants that results in seed formation without the involvement of meiosis or fertilization of the egg. Seeds formed on an apomictic plant contain offspring genetically identical to the maternal plant. Apomixis has significant potential for preserving hybrid vigor from one generation to the next in highly productive crop plant genotypes. Apomictic Pennisetum/Cenchrus species, members of the Poaceae (grass) family, reproduce by apospory. Apospory is characterized by apomeiosis, the formation of unreduced embryo sacs derived from nucellar cells of the ovary and, by parthenogenesis, the development of the unreduced egg into an embryo without fertilization. In Pennisetum squamulatum (L.) R.Br., apospory segregates as a single dominant locus, the apospory-specific genomic region (ASGR). In this study, we demonstrate that the PsASGR-BABY BOOM-like (PsASGR-BBML) gene is expressed in egg cells before fertilization and can induce parthenogenesis and the production of haploid offspring in transgenic sexual pearl millet. A reduction of PsASGR-BBML expression in apomictic F1 RNAi transgenic plants results in fewer visible parthenogenetic embryos and a reduction of embryo cell number compared with controls. Our results endorse a key role for PsASGR-BBML in parthenogenesis and a newly discovered role for a member of the BBM-like clade of APETALA 2 transcription factors. Induction of parthenogenesis by PsASGR-BBML will be valuable for installing parthenogenesis to synthesize apomixis in crops and will have further application for haploid induction to rapidly obtain homozygous lines for breeding.

  9. A parthenogenesis gene of apomict origin elicits embryo formation from unfertilized eggs in a sexual plant

    Science.gov (United States)

    Conner, Joann A.; Mookkan, Muruganantham; Huo, Heqiang; Chae, Keun; Ozias-Akins, Peggy

    2015-01-01

    Apomixis is a naturally occurring mode of asexual reproduction in flowering plants that results in seed formation without the involvement of meiosis or fertilization of the egg. Seeds formed on an apomictic plant contain offspring genetically identical to the maternal plant. Apomixis has significant potential for preserving hybrid vigor from one generation to the next in highly productive crop plant genotypes. Apomictic Pennisetum/Cenchrus species, members of the Poaceae (grass) family, reproduce by apospory. Apospory is characterized by apomeiosis, the formation of unreduced embryo sacs derived from nucellar cells of the ovary and, by parthenogenesis, the development of the unreduced egg into an embryo without fertilization. In Pennisetum squamulatum (L.) R.Br., apospory segregates as a single dominant locus, the apospory-specific genomic region (ASGR). In this study, we demonstrate that the PsASGR-BABY BOOM-like (PsASGR-BBML) gene is expressed in egg cells before fertilization and can induce parthenogenesis and the production of haploid offspring in transgenic sexual pearl millet. A reduction of PsASGR-BBML expression in apomictic F1 RNAi transgenic plants results in fewer visible parthenogenetic embryos and a reduction of embryo cell number compared with controls. Our results endorse a key role for PsASGR-BBML in parthenogenesis and a newly discovered role for a member of the BBM-like clade of APETALA 2 transcription factors. Induction of parthenogenesis by PsASGR-BBML will be valuable for installing parthenogenesis to synthesize apomixis in crops and will have further application for haploid induction to rapidly obtain homozygous lines for breeding. PMID:26305939

  10. [Sex structure and seed productivity of Mentha canadensis L. from natural flora of primorye of Russia].

    Science.gov (United States)

    Voronkova, T V; Shelepova, O V; Kondrat'eva, V V; Bidiukova, G F

    2014-01-01

    The sex structure and seed productivity of Mentha canadensis L. from different climatic regioins of Primorye of Russia was studied. We established that M. canadensis is characterized by a homogeneous population structure due to the formation of vegetative clones. The ratio of female and androgynous individuals was 1:5, and it is possible that this is a species-specific trait. Both sexual forms produced fruits under conditions of isolation from cross-pollination. We discuss the possibility of apomixis and the influence of climatic conditions on seed productivity and morphometric characteristics of plants.

  11. Identification of ovule transcripts from the Apospory-Specific Genomic Region (ASGR-carrier chromosome

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    Ozias-Akins Peggy

    2011-04-01

    Full Text Available Abstract Background Apomixis, asexual seed production in plants, holds great potential for agriculture as a means to fix hybrid vigor. Apospory is a form of apomixis where the embryo develops from an unreduced egg that is derived from a somatic nucellar cell, the aposporous initial, via mitosis. Understanding the molecular mechanism regulating aposporous initial specification will be a critical step toward elucidation of apomixis and also provide insight into developmental regulation and downstream signaling that results in apomixis. To discover candidate transcripts for regulating aposporous initial specification in P. squamulatum, we compared two transcriptomes derived from microdissected ovules at the stage of aposporous initial formation between the apomictic donor parent, P. squamulatum (accession PS26, and an apomictic derived backcross 8 (BC8 line containing only the Apospory-Specific Genomic Region (ASGR-carrier chromosome from P. squamulatum. Toward this end, two transcriptomes derived from ovules of an apomictic donor parent and its apomictic backcross derivative at the stage of apospory initiation, were sequenced using 454-FLX technology. Results Using 454-FLX technology, we generated 332,567 reads with an average read length of 147 base pairs (bp for the PS26 ovule transcriptome library and 363,637 reads with an average read length of 142 bp for the BC8 ovule transcriptome library. A total of 33,977 contigs from the PS26 ovule transcriptome library and 26,576 contigs from the BC8 ovule transcriptome library were assembled using the Multifunctional Inertial Reference Assembly program. Using stringent in silico parameters, 61 transcripts were predicted to map to the ASGR-carrier chromosome, of which 49 transcripts were verified as ASGR-carrier chromosome specific. One of the alien expressed genes could be assigned as tightly linked to the ASGR by screening of apomictic and sexual F1s. Only one transcript, which did not map to the ASGR

  12. The Behavior of Chromosomes During Parthenogenetic Oogenesis in Marmorkrebs Procambarus fallax f. virginalis.

    Science.gov (United States)

    Kato, Miku; Hiruta, Chizue; Tochinai, Shin

    2016-08-01

    Parthenogenetic oogenesis varies among and even within species. Based on cytological mechanisms, it can largely be divided into apomixis (ameiotic parthenogenesis) producing genetically identical progeny, and automixis (meiotic parthenogenesis) producing genetically non-identical progeny. Polyploidy is common in parthenogenetic species, although the association between parthenogenesis and polyploidy throughout evolution is poorly understood. Marmorkrebs, or the marbled crayfish, was first identified as a parthenogenetic decapod and was tentatively named as Procambarus fallax f. virginalis. Previous studies revealed that Marmorkrebs is triploid and produces genetically identical offspring, suggesting that apomixis occurs during parthenogenetic oogenesis. However, the behavior of chromosomes during the process of oogenesis is still not well characterized. In this study, we observed parthenogenetic oogenesis around the time of ovulation in P. fallax f. virginalis by histology and immunohistochemistry. During oogenesis, the chromosomes were separated into two groups and behaved independently from each other, and one complete division corresponding to mitosis (the second meiosis-like division) was observed. This suggests that parthenogenetic oogenesis in Marmorkrebs exhibits gonomery, a phenomenon commonly found in apomictic parthenogenesis in polyploid animals.

  13. Short Communication: An apospory-specific genomic region is conserved between Buffelgrass (Cenchrus ciliaris L.) and Pennisetum squamulatum Fresen.

    Science.gov (United States)

    Roche; Cong; Chen; Hanna; Gustine; Sherwood; Ozias-Akins

    1999-07-01

    Twelve molecular markers linked to pseudogamous apospory, a form of gametophytic apomixis, were previously isolated from Pennisetum squamulatum Fresen. No recombination between these markers was found in a segregating population of 397 individuals (Ozias-Akins et al. 1998, Proc. Natl Acad. Sci. USA, 95, 5127-5132). The objective of the present study was to test if these markers were also linked to the aposporous mode of reproduction in two small segregating populations of Cenchrus ciliaris (= Pennisetum ciliare (L.)Link), another apomictic grass species. Among 12 markers (sequence characterized amplified regions, SCARs), six were scored as dominant markers between aposporous and sexual C. ciliaris genotypes (presence/absence, respectively). Five were always linked to apospory and one showed a low level of recombination in 84 progenies. Restriction fragment length polymorphisms (RFLPs) were observed between sexual and apomictic phenotypes for three of the six remaining SCARs from P. squamulatum when used as probes. No recombination was observed in the F1 progenies. Preliminary data from megabase DNA analysis and sequencing in both species indicate that an apospory-specific genomic region (ASGR) is highly conserved between the two species. Although C. ciliaris has a smaller genome size to P. squamulatum, a higher copy number for markers linked to apospory found in the former may impair the progress of positional cloning of gene(s) for apomixis in this species.

  14. Comparative gene expression in sexual and apomictic ovaries of Pennisetum ciliare (L.) Link.

    Science.gov (United States)

    Vielle-Calzada, J P; Nuccio, M L; Budiman, M A; Thomas, T L; Burson, B L; Hussey, M A; Wing, R A

    1996-12-01

    Limited emphasis has been given to the molecular study of apomixis, an asexual method of reproduction where seeds are produced without fertilization. Most buffelgrass (Pennisetum ciliare (L.) Link syn = Cenchrus ciliaris L.) genotypes reproduce by obligate apomixis (apospory); however, rare sexual plants have been recovered. A modified differential display procedure was used to compare gene expression in unpollinated ovaries containing ovules with either sexual or apomictic female gametophytes. The modification incorporated end-labeled poly(A)+ anchored primers as the only isotopic source, and was a reliable and consistent approach for detecting differentially displayed transcripts. Using 20 different decamers and two anchor primers, 2268 cDNA fragments between 200 and 600 bp were displayed. From these, eight reproducible differentially displayed cDNAs were identified and cloned. Based on northern analysis, one cDNA was detected in only the sexual ovaries, two cDNAs in only apomictic ovaries and one cDNA was present in both types of ovaries. Three fragments could not be detected and one fragment was detected in ovaries, stems, and leaves. Comparison of gene expression during sexual and apomictic development in buffelgrass represents a new model system and a strategy for investigating female reproductive development in the angiosperms.

  15. Isolation of candidate genes for apomictic development in buffelgrass (Pennisetum ciliare).

    Science.gov (United States)

    Singh, Manjit; Burson, Byron L; Finlayson, Scott A

    2007-08-01

    Asexual reproduction through seeds, or apomixis, is a process that holds much promise for agricultural advances. However, the molecular mechanisms underlying apomixis are currently poorly understood. To identify genes related to female gametophyte development in apomictic ovaries of buffelgrass (Pennisetum ciliare (L.) Link), Suppression Subtractive Hybridization of ovary cDNA with leaf cDNA was performed. Through macroarray screening of subtracted cDNAs two genes were identified, Pca21 and Pca24, that showed differential expression between apomictic and sexual ovaries. Sequence analysis showed that both Pca21 and Pca24 are novel genes not previously characterized in plants. Pca21 shows homology to two wheat genes that are also expressed during reproductive development. Pca24 has similarity to coiled-coil-helix-coiled-coil-helix (CHCH) domain containing proteins from maize and sugarcane. Northern blot analysis revealed that both of these genes are expressed throughout female gametophyte development in apomictic ovaries. In situ hybridizations localized the transcript of these two genes to the developing embryo sacs in the apomictic ovaries. Based on the expression patterns it was concluded that Pca21 and Pca24 likely play a role during apomictic development in buffelgrass.

  16. Depletion of Key Meiotic Genes and Transcriptome-Wide Abiotic Stress Reprogramming Mark Early Preparatory Events Ahead of Apomeiotic Transition

    Science.gov (United States)

    Shah, Jubin N.; Kirioukhova, Olga; Pawar, Pallavi; Tayyab, Muhammad; Mateo, Juan L.; Johnston, Amal J.

    2016-01-01

    Molecular dissection of apomixis – an asexual reproductive mode – is anticipated to solve the enigma of loss of meiotic sex, and to help fixing elite agronomic traits. The Brassicaceae genus Boechera comprises of both sexual and apomictic species, permitting comparative analyses of meiotic circumvention (apomeiosis) and parthenogenesis. Whereas previous studies reported local transcriptome changes during these events, it remained unclear whether global changes associated with hybridization, polyploidy and environmental adaptation that arose during evolution of Boechera might serve as (epi)genetic regulators of early development prior apomictic initiation. To identify these signatures during vegetative stages, we compared seedling RNA-seq transcriptomes of an obligate triploid apomict and a diploid sexual, both isolated from a drought-prone habitat. Uncovered were several genes differentially expressed between sexual and apomictic seedlings, including homologs of meiotic genes ASYNAPTIC 1 (ASY1) and MULTIPOLAR SPINDLE 1 (MPS1) that were down-regulated in apomicts. An intriguing class of apomict-specific deregulated genes included several NAC transcription factors, homologs of which are known to be transcriptionally reprogrammed during abiotic stress in other plants. Deregulation of both meiotic and stress-response genes during seedling stages might possibly be important in preparation for meiotic circumvention, as similar transcriptional alteration was discernible in apomeiotic floral buds too. Furthermore, we noted that the apomict showed better tolerance to osmotic stress in vitro than the sexual, in conjunction with significant upregulation of a subset of NAC genes. In support of the current model that DNA methylation epigenetically regulates stress, ploidy, hybridization and apomixis, we noted that ASY1, MPS1 and NAC019 homologs were deregulated in Boechera seedlings upon DNA demethylation, and ASY1 in particular seems to be repressed by global DNA

  17. Depletion of Key Meiotic Genes and Transcriptome-Wide Abiotic Stress Reprogramming Mark Early Preparatory Events Ahead of Apomeiotic Transition

    Directory of Open Access Journals (Sweden)

    Jubin N Shah

    2016-10-01

    Full Text Available Molecular dissection of apomixis - an asexual reproductive mode - is anticipated to solve the enigma of loss of meiotic sex, and to help fixing elite agronomic traits. The Brassicaceae genus Boechera comprises of both sexual and apomictic species, permitting comparative analyses of meiotic circumvention (apomeiosis and parthenogenesis. Whereas previous studies reported local transcriptome changes during these events, it remained unclear whether global changes associated with hybridization, polyploidy and environmental adaptation that arose during evolution of Boechera might hint as (epigenetic regulators of early development prior apomictic initiation. To identify these signatures during vegetative stages, we compared seedling RNA-seq transcriptomes of an obligate triploid apomict and a diploid sexual, both isolated from a drought-prone habitat. Uncovered were several genes differentially expressed between sexual and apomictic seedlings, including homologues of meiotic genes ASYNAPTIC 1 (ASY1 and MULTIPOLAR SPINDLE 1 (MPS1 that were down-regulated in apomicts. An intriguing class of apomict-specific deregulated genes included several NAC transcription factors, homologues of which are known to be transcriptionally reprogrammed during abiotic stress in other plants. Deregulation of both meiotic and stress-response genes during seedling stages might possibly be important in preparation for meiotic circumvention, as similar transcriptional alteration was discernible in apomeiotic floral buds too. Furthermore, we noted that the apomict showed better tolerance to osmotic stress in vitro than the sexual, in conjunction with significant upregulation of a subset of NAC genes. In support of the current model that DNA methylation epigenetically regulates stress, ploidy, hybridization and apomixis, we noted that ASY1, MPS1 and NAC019 homologues were deregulated in Boechera seedlings upon DNA demethylation, and ASY1 in particular seems to be repressed by

  18. Induced mutations in apomictic variety of maize-tripsacum hybrid

    International Nuclear Information System (INIS)

    Yudin, B.F.; Lukina, L.A.

    1983-01-01

    Three generations of six mutants obtained by γ- and x-irradiation of seeds of highly apomictic variety of 38 chromosome maize-tripsacum hybrid have been studied. Radiomutants detected in M 2 preserved the mother type and constance in M 3 and M 4 . One of the mutants, as an exception, manifested somatic splitting, which resulted in the appearance of a new apomictic clone. Irradiation and mutation in some cases were accompanied by the appearance of seedlings with high chromosome numbers in mutant posterity, including apomicts with doubled number of chromosomes, as well as the increase of total part of sexual reproduction; the latter circumstance is considered as a result of modificator balance change caused by treatments. Doubling of chromosome number in 38-chromosome apomicts, according to preliminary data, does not affect significantly the way of reproduction; 76-chromosome forms preserve a high degree of a regular apomixis

  19. Comparative proteomic analysis of apomictic monosomic addition line of Beta corolliflora and Beta vulgaris L. in sugar beet.

    Science.gov (United States)

    Zhu, Hong; Bi, Ying-Dong; Yu, Li-Jie; Guo, De-Dong; Wang, Bai-Chen

    2009-11-01

    Apomixis refers to a process in which plants produce seed without fertilization through female syngamy that produces embryos genetically identical to the maternal parent. In sugar beet, interspecific hybrids between diploid Beta vulgaris and tetraploid Beta corolliflora were established and monosomic addition line M14 was selected because of the apomictic phenotype. By using two-dimensional electrophoresis gels we identified the proteins which were differently expressed between the M14 and B. vulgaris. A total of 27 protein spots which varied expressed between lines were isolated and successfully identified with MALDI-TOF MS. Among them five protein spots were found to be only presented in M14 and two protein spots only expressed in Beta. According to their functional annotations described in Swissprot database, these proteins were, respectively, involved in important biological pathways, such as cell division, functionally classified using the KEGG functional classification system. The result may be useful for us to better understand the genetic mechanism of apomixes.

  20. Biología reproductiva de Convolvulus chilensis (Convolvulaceae en una población de Aucó (centro-norte de Chile Reproductive biology of Convolvulus chilensis (Convolvulaceae in a population of Aucó (north-central Chile

    Directory of Open Access Journals (Sweden)

    Lorena H. Suárez

    2004-12-01

    Full Text Available Convolvulus chilensis es una hierba perenne, única representante endémica de la familia Convolvulaceae en Chile. Se estudió el sistema de reproducción, fenología, morfología y longevidad floral de C. chilensis en una población natural ubicada en la localidad de Aucó, dentro de la Reserva Nacional Las Chinchillas, IV Región, Chile. Se montó un experimento de polinización controlada considerando los tratamientos de polinización natural, polinización cruzada, autopolinización manual, autopolinización automática y apomixis, evaluándose su efecto sobre la formación de frutos y el número de semillas producidas por fruto. Adicionalmente, se compararon los siguientes atributos de la progenie según tipo de polinización (autopolinización o polinización cruzada: peso de semilla, germinación, altura y número de hojas de plántulas de ocho semanas en condiciones de invernadero. Se encontró que C. chilensis es una especie autocompatible, parcialmente autógama (capaz de autopolinizarse sin mediador y parcialmente apomíctica (capaz de producir semillas sin participación de gameto masculino. La longevidad floral fue estimada en 5,25 h. Durante este período, aproximadamente en 1,5 h hay disponibilidad de polen en los estambres. El período de floración se extiende por 22 semanas (agosto a enero. El tratamiento de apomixis presentó el menor porcentaje de formación de frutos y la menor cantidad de semillas por flor en comparación a los tratamientos de polinización natural, cruzada manual, autopolinización automática y autopolinización manual, los cuales no mostraron diferencias entre sí en ambos atributos. El tipo de polinización (autopolinización o polinización cruzada no afecta el desempeño de la progenie en los atributos de semilla y plántula evaluadosThe perennial herb Convolvulus chilensis is the only endemic species of the Convolvulaceae in Chile. The breeding system, phenology, morphology and floral longevity of C

  1. Breeding systems in some representatives of the genus Lycium (Solanaceae

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    L. Minne

    1994-10-01

    Full Text Available The development of the ovule and the embryo sac of five of the 17 species of Lycium and of one hybrid, recorded for southern Africa, was investigated. All specimens of four of the species and the hybrid (between a hermaphroditic and a functionally dioecious species were found to be functionally dioecious: they express only one sex, although both male and female organs are present in the same tlower. One species was hermaphroditic. The embryo sacs of all species, and of the hybrid, were of the normal eight-nucleate Polygonum type. The structure of the ovary and the development of the embryo sac are similar to those of L europaeum L. The absence of unreduced embryo sacs indicates that apomixis does not occur at any ploidy level in the species studied.

  2. Meiosis, unreduced gametes, and parthenogenesis: implications for engineering clonal seed formation in crops.

    Science.gov (United States)

    Ronceret, Arnaud; Vielle-Calzada, Jean-Philippe

    2015-06-01

    Meiosis and unreduced gametes. Sexual flowering plants produce meiotically derived cells that give rise to the male and female haploid gametophytic phase. In the ovule, usually a single precursor (the megaspore mother cell) undergoes meiosis to form four haploid megaspores; however, numerous mutants result in the formation of unreduced gametes, sometimes showing female specificity, a phenomenon reminiscent of the initiation of gametophytic apomixis. Here, we review the developmental events that occur during female meiosis and megasporogenesis at the light of current possibilities to engineer unreduced gamete formation. We also provide an overview of the current understanding of mechanisms leading to parthenogenesis and discuss some of the conceptual implications for attempting the induction of clonal seed production in cultivated plants.

  3. Chromosome engineering: power tools for plant genetics.

    Science.gov (United States)

    Chan, Simon W L

    2010-12-01

    The term "chromosome engineering" describes technologies in which chromosomes are manipulated to change their mode of genetic inheritance. This review examines recent innovations in chromosome engineering that promise to greatly increase the efficiency of plant breeding. Haploid Arabidopsis thaliana have been produced by altering the kinetochore protein CENH3, yielding instant homozygous lines. Haploid production will facilitate reverse breeding, a method that downregulates recombination to ensure progeny contain intact parental chromosomes. Another chromosome engineering success is the conversion of meiosis into mitosis, which produces diploid gametes that are clones of the parent plant. This is a key step in apomixis (asexual reproduction through seeds) and could help to preserve hybrid vigor in the future. New homologous recombination methods in plants will potentiate many chromosome engineering applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. The induced mutagenesis and the genetic progress in the work with sour cherry

    International Nuclear Information System (INIS)

    Zhukov, O.S.

    1990-01-01

    Full text: We used radiation breeding for improving sour cherry varieties since 1958. X- and gamma-rays and also other physical factors have been applied to cuttings, seeds, flower parts and whole plants as well as in-vitro cultures. Doses of 30-60 Gy appeared to be most effective for inducing mutation when cuttings were irradiated. The main number of mutations occurred in M 1 and M 2 . Mutations were divided into 5 main classes concerning morphological characters, tree growth, dates of fruit bearing, biochemical composition, system of propagation. As a result of x-irradiation of a sour cherry/bird cherry hybrid 'Padocerus', immune to Coccomyces hiemalis, a highly fertile mutant 'Padocerus M' has been obtained. A dominant gene has been identified, controlling resistance to Coccomyces hiemalis. By obtaining 'Padocerus M' the possibilities of increasing the genetic resources have been expanded. 'Almaz' is the monogenic donor of resistance to C. hiemalis. In literature there are indications of the possibility of obtaining apomictic forms by mutagenesis. As a result of irradiating 'Padocerus' plants in the gamma field during three years a mutant has been found in which the basic mass of seeds is formed as a result of apomixis-autonomous diplosporic parthenogenesis. Apomixis seems to be controlled by a small number of major and minor genes. The mutant is called 'Padocerus A' and is used in hybridisation with other sour cherry varieties; segregation for the apomictic type of propagation has been found. A population of Prunus fructicosa has been studied in the region of the so-called Tatar bank in the Tambov district. Large-fruited forms have been selected which may be the result of accumulating spontaneous mutations. Mutations of a different type have been obtained when using chemical mutagens or a laser beam. (author)

  5. Reticulate evolution in North American black-fruited hawthorns (Crataegus section Douglasia; Rosaceae): evidence from nuclear ITS2 and plastid sequences.

    Science.gov (United States)

    Zarrei, M; Stefanović, S; Dickinson, T A

    2014-08-01

    The taxonomic complexity of Crataegus (hawthorn; Rosaceae, Maleae), especially in North America, has been attributed by some to hybridization in combination with gametophytic apomixis and polyploidization, whereas others have considered the roles of hybridization and apomixis to be minimal. Study of the chemical composition and therapeutic value of hawthorn extracts requires reproducible differentiation of entities that may be difficult to distinguish by morphology alone. This study sought to address this by using the nuclear ribosomal spacer region ITS2 as a supplementary DNA barcode; however, a lack of success prompted an investigation to discover why this locus gave unsatisfactory results. ITS2 was extensively cloned so as to document inter- and intraindividual variation in this locus, using hawthorns of western North America where the genus Crataegus is represented by only two widely divergent groups, the red-fruited section Coccineae and the black-fruited section Douglasia. Additional sequence data from selected loci on the plastid genome were obtained to enhance further the interpretation of the ITS2 results. In the ITS2 gene tree, ribotypes from western North American hawthorns are found in two clades. Ribotypes from diploid members of section Douglasia occur in one clade (with representatives of the east-Asian section Sanguineae). The other clade comprises those from diploid and polyploid members of section Coccineae. Both clades contribute ribotypes to polyploid Douglasia. Data from four plastid-derived intergenic spacers demonstrate the maternal parentage of these allopolyploids. Repeated hybridization between species of section Douglasia and western North American members of section Coccineae involving the fertilization of unreduced female gametes explains the observed distribution of ribotypes and accounts for the phenetic intermediacy of many members of section Douglasia. © The Author 2014. Published by Oxford University Press on behalf of the Annals

  6. Reproductive biology of Aechmea bracteata (Sw.) Griseb. (Bromelioideae: Bromeliaceae).

    Science.gov (United States)

    Pool-Chalé, M; Ramírez-Morillo, I; Carnevali Fernández-Concha, G; Hornung-Leoni, C T

    2018-01-01

    Individuals of Aechmea bracteata show inflorescences with red scape bracts and odourless, yellow, tubular diurnal flowers, with closely arranged sexual organs, producing a large amount of fruits. In order to investigate the reproductive system of this species, a suite of characters was assessed: phenology, floral morphology and biology, nectar production dynamics, and fruit and seed production and germination, as a result of controlled pollination crosses. The study was conducted during two flowering seasons in wild populations in Yucatán, Mexico. Results suggest an annual flowering pattern with one flowering peak; flowers were diurnal, showing partial dichogamy (protandry)-herkogamy, anthers and stigma become mature before floral aperture, which could lead to self-pollination, nectar is produced during anthesis, varying in volume and total sugar concentration during the day; fruits and seeds were produced in all experimental crosses (cross-pollination, obligated cross-pollination, assisted and unassisted selfing, geitonogamy and apomixis), as well as high percentage seed germination. Several species of Aechmea are reportedly self-compatible and autogamous, as suggested by results of selfing and non-assisted selfing crosses, but these results are negated by the presence of apomixis, indicating that the species is apomictic. This is the first report of this breeding system for subgenus Aechmea and the sixth for Bromeliaceae. Polyembryony is here suggested for the first time in this genus and family based on the fact that more seeds were recorded that expected based on ovule numbers. Finally, when performing experimental crosses, estimating reproductive success based on number of seeds is a better approach than number of fruits, due to the effect of pseudogamy. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

  7. A Parthenogenesis Gene Candidate and Evidence for Segmental Allopolyploidy in Apomictic Brachiaria decumbens.

    Science.gov (United States)

    Worthington, Margaret; Heffelfinger, Christopher; Bernal, Diana; Quintero, Constanza; Zapata, Yeny Patricia; Perez, Juan Guillermo; De Vega, Jose; Miles, John; Dellaporta, Stephen; Tohme, Joe

    2016-07-01

    Apomixis, asexual reproduction through seed, enables breeders to identify and faithfully propagate superior heterozygous genotypes by seed without the disadvantages of vegetative propagation or the expense and complexity of hybrid seed production. The availability of new tools such as genotyping by sequencing and bioinformatics pipelines for species lacking reference genomes now makes the construction of dense maps possible in apomictic species, despite complications including polyploidy, multisomic inheritance, self-incompatibility, and high levels of heterozygosity. In this study, we developed saturated linkage maps for the maternal and paternal genomes of an interspecific Brachiaria ruziziensis (R. Germ. and C. M. Evrard) × B. decumbens Stapf. F1 mapping population in order to identify markers linked to apomixis. High-resolution molecular karyotyping and comparative genomics with Setaria italica (L.) P. Beauv provided conclusive evidence for segmental allopolyploidy in B. decumbens, with strong preferential pairing of homologs across the genome and multisomic segregation relatively more common in chromosome 8. The apospory-specific genomic region (ASGR) was mapped to a region of reduced recombination on B. decumbens chromosome 5. The Pennisetum squamulatum (L.) R.Br. PsASGR-BABY BOOM-like (psASGR-BBML)-specific primer pair p779/p780 was in perfect linkage with the ASGR in the F1 mapping population and diagnostic for reproductive mode in a diversity panel of known sexual and apomict Brachiaria (Trin.) Griseb. and P. maximum Jacq. germplasm accessions and cultivars. These findings indicate that ASGR-BBML gene sequences are highly conserved across the Paniceae and add further support for the postulation of the ASGR-BBML as candidate genes for the apomictic function of parthenogenesis. Copyright © 2016 by the Genetics Society of America.

  8. A Parthenogenesis Gene Candidate and Evidence for Segmental Allopolyploidy in Apomictic Brachiaria decumbens

    Science.gov (United States)

    Worthington, Margaret; Heffelfinger, Christopher; Bernal, Diana; Quintero, Constanza; Zapata, Yeny Patricia; Perez, Juan Guillermo; De Vega, Jose; Miles, John; Dellaporta, Stephen; Tohme, Joe

    2016-01-01

    Apomixis, asexual reproduction through seed, enables breeders to identify and faithfully propagate superior heterozygous genotypes by seed without the disadvantages of vegetative propagation or the expense and complexity of hybrid seed production. The availability of new tools such as genotyping by sequencing and bioinformatics pipelines for species lacking reference genomes now makes the construction of dense maps possible in apomictic species, despite complications including polyploidy, multisomic inheritance, self-incompatibility, and high levels of heterozygosity. In this study, we developed saturated linkage maps for the maternal and paternal genomes of an interspecific Brachiaria ruziziensis (R. Germ. and C. M. Evrard) × B. decumbens Stapf. F1 mapping population in order to identify markers linked to apomixis. High-resolution molecular karyotyping and comparative genomics with Setaria italica (L.) P. Beauv provided conclusive evidence for segmental allopolyploidy in B. decumbens, with strong preferential pairing of homologs across the genome and multisomic segregation relatively more common in chromosome 8. The apospory-specific genomic region (ASGR) was mapped to a region of reduced recombination on B. decumbens chromosome 5. The Pennisetum squamulatum (L.) R.Br. PsASGR-BABY BOOM-like (psASGR–BBML)-specific primer pair p779/p780 was in perfect linkage with the ASGR in the F1 mapping population and diagnostic for reproductive mode in a diversity panel of known sexual and apomict Brachiaria (Trin.) Griseb. and P. maximum Jacq. germplasm accessions and cultivars. These findings indicate that ASGR–BBML gene sequences are highly conserved across the Paniceae and add further support for the postulation of the ASGR–BBML as candidate genes for the apomictic function of parthenogenesis. PMID:27206716

  9. Microsatellite markers for Urochloa humidicola (Poaceae) and their transferability to other Urochloa species.

    Science.gov (United States)

    Santos, Jean C S; Barreto, Mariana A; Oliveira, Fernanda A; Vigna, Bianca B Z; Souza, Anete P

    2015-03-15

    Urochloa humidicola is a warm-season grass commonly used as forage in the tropics and is recognized for its tolerance to seasonal flooding. This grass is an important forage species for the Cerrado and Amazon regions of Brazil. U. humidicola is a polyploid species with variable ploidy (6X-9X) and facultative apomixis with high phenotypic plasticity. However, this apomixis and ploidy, as well as the limited knowledge of the genetic basis of the germplasm collection, have constrained genetic breeding activities, yet microsatellite markers may enable a better understanding of the species' genetic composition. This study aimed to develop and characterize new polymorphic microsatellite molecular markers in U. humidicola and to evaluate their transferability to other Urochloa species. A set of microsatellite markers for U. humidicola was identified from two new enriched genomic DNA libraries: the first library was constructed from a single sexual genotype and the second from a pool of eight apomictic genotypes selected on the basis of previous results. Of the 114 loci developed, 72 primer pairs presented a good amplification product, and 64 were polymorphic among the 34 genotypes tested. The number of bands per simple sequence repeat (SSR) locus ranged from 1 to 29, with a mean of 9.6 bands per locus. The mean polymorphism information content (PIC) of all loci was 0.77, and the mean discrimination power (DP) was 0.87. STRUCTURE analysis revealed differences among U. humidicola accessions, hybrids, and other Urochloa accessions. The transferability of these microsatellites was evaluated in four species of the genus, U. brizantha, U. decumbens, U. ruziziensis, and U. dictyoneura, and the percentage of transferability ranged from 58.33% to 69.44% depending on the species. This work reports new polymorphic microsatellite markers for U. humidicola that can be used for breeding programs of this and other Urochloa species, including genetic linkage mapping, quantitative trait

  10. Study of Genetics and Embryology of Polyembryonic Mutant of Autotetraploid Rice Induced by N+ Beam Implantation

    Science.gov (United States)

    Dai, Ximei; Huang, Qunce; Li, Guoping; Hu, Xiuming; Qin, Guangyong; Yu, Zengliang

    2006-11-01

    In the present study autotetraploid rice IR36-4X was treated by an ion implantation technique with nitrogen ion beams. A polyembryonic mutant (named IR36-Shuang) was identified in the M2 generation. The mutant line and its offspring were systematically investigated in regard to their major agronomic properties and the rate of polyembryonic seedling in the M3-M6 generation. The abnormal phenomena in the embryo sac development and the cytological mechanism of the initiation of additional embryo in IR36-Shuang were observed by Laser Scanning Confocal Microscopy. The results were as follows. 1) The plant height, the panicle length and 1000 grain weight of IR36-Shuang were lower than that of its control by 35.41%, 5.08% and 15.72% respectively, Moreover, the setting percentage decreased 12.39% compared with that in normal IR36-4X plants. 2) The polyembryonic trait of IR36-Shuang was genetically stable and the frequency of the polyembryonic seedlings in the IR36-Shuang line was also relatively stable. 3) The rate of abnormal embryo sacs in IR36-Shuang was significantly higher than that in the control IR36-4X. 4) The additional embryo in IR36-Shuang might arise from the double set of embryo sacs in a single ovary, antipodal cells or endosperm cells. These results suggest that IR36-Shuang is a polyembryonic mutant and a new apomixis rice line induced by low energy ion implantation. The prospects for the application in production of the IR36-Shuang line are also discussed. The present study may provide a basis for future investigations of apomixis rice breeding via the ion implantation biotechnology.

  11. Selection and validation of reference genes for gene expression analysis in apomictic and sexual Cenchrus ciliaris

    Science.gov (United States)

    2013-01-01

    Background Apomixis is a naturally occurring asexual mode of seed reproduction resulting in offspring genetically identical to the maternal plant. Identifying differential gene expression patterns between apomictic and sexual plants is valuable to help deconstruct the trait. Quantitative RT-PCR (qRT-PCR) is a popular method for analyzing gene expression. Normalizing gene expression data using proper reference genes which show stable expression under investigated conditions is critical in qRT-PCR analysis. We used qRT-PCR to validate expression and stability of six potential reference genes (EF1alpha, EIF4A, UBCE, GAPDH, ACT2 and TUBA) in vegetative and reproductive tissues of B-2S and B-12-9 accessions of C. ciliaris. Findings Among tissue types evaluated, EF1alpha showed the highest level of expression while TUBA showed the lowest. When all tissue types were evaluated and compared between genotypes, EIF4A was the most stable reference gene. Gene expression stability for specific ovary stages of B-2S and B-12-9 was also determined. Except for TUBA, all other tested reference genes could be used for any stage-specific ovary tissue normalization, irrespective of the mode of reproduction. Conclusion Our gene expression stability assay using six reference genes, in sexual and apomictic accessions of C. ciliaris, suggests that EIF4A is the most stable gene across all tissue types analyzed. All other tested reference genes, with the exception of TUBA, could be used for gene expression comparison studies between sexual and apomictic ovaries over multiple developmental stages. This reference gene validation data in C. ciliaris will serve as an important base for future apomixis-related transcriptome data validation. PMID:24083672

  12. Biologia floral e polinização artificial de pinhão-manso no norte de Minas Gerais Floral biology and artificial polinization in physic nut in the north of Minas Gerais state, Brazil

    Directory of Open Access Journals (Sweden)

    Ana Cristina Pinto Juhász

    2009-09-01

    Full Text Available O objetivo deste trabalho foi avaliar alguns aspectos da biologia floral e do sistema reprodutivo de Jatropha curcas, em Janaúba, MG. Foram registrados: o número de flores femininas e masculinas; o intervalo de abertura das flores femininas; e a formação de frutos por apomixia, autofecundação, geitonogamia e xenogamia. A proporção de flores masculinas para femininas foi de 20:1. O intervalo de abertura das flores femininas variou de um a sete dias, conforme o número delas na inflorescência. No teste de apomixia, houve formação de frutos em apenas 5% das flores avaliadas. A percentagem de frutificação variou de 79 a 88% na autofecundação manual, na geitonogamia e na xenogamia. Na autofecundação sem a polinização manual a frutificação foi de 20%, e os frutos formados foram significativamente menores, com número inferior de sementes por fruto e menor índice de velocidade de emergência. As sementes foram semelhantes às formadas por polinização natural. é possível a realização de cruzamentos controlados em pinhão-manso, e não há autoincompatibilidade nesta espécie.The aim of this work was to evaluate some aspects of the floral biology and of the reproductive system of Jatropha curcas, in Janaúba county, MG, Brazil. The number of female and male flowers, the interval between the opening of female flowers, and the formation of fruits by apomixis, self-pollination, geitonogamy and by xenogamy were registered. The ratio of male to female flowers was 20:1. The interval of opening of female flowers was of one to seven days, depending on the number of female flowers in the inflorescence. On the apomixy test, the formation of fruits occurred in only 5% of the evaluated flowers. The fruit set was between 79 and 88% through the manual self-pollination, and through the geitonogamy, and the xenogamy. In the self-pollination treatment, without the hand-pollination, the fruit set was of 20%, and the fruits formed were

  13. The pattern of genetic variability in apomictic clones of Taraxacum officinale indicates the alternation of asexual and sexual histories of apomicts.

    Science.gov (United States)

    Majeský, Luboš; Vašut, Radim J; Kitner, Miloslav; Trávníček, Bohumil

    2012-01-01

    Dandelions (genus Taraxacum) comprise a group of sexual diploids and apomictic polyploids with a complicated reticular evolution. Apomixis (clonal reproduction through seeds) in this genus is considered to be obligate, and therefore represent a good model for studying the role of asexual reproduction in microevolutionary processes of apomictic genera. In our study, a total of 187 apomictic individuals composing a set of nine microspecies (sampled across wide geographic area in Europe) were genotyped for six microsatellite loci and for 162 amplified fragment length polymorphism (AFLP) markers. Our results indicated that significant genetic similarity existed within accessions with low numbers of genotypes. Genotypic variability was high among accessions but low within accessions. Clustering methods discriminated individuals into nine groups corresponding to their phenotypes. Furthermore, two groups of apomictic genotypes were observed, which suggests that they had different asexual histories. A matrix compatibility test suggests that most of the variability within accession groups was mutational in origin. However, the presence of recombination was also detected. The accumulation of mutations in asexual clones leads to the establishment of a network of clone mates. However, this study suggests that the clones primarily originated from the hybridisation between sexual and apomicts.

  14. The pattern of genetic variability in apomictic clones of Taraxacum officinale indicates the alternation of asexual and sexual histories of apomicts.

    Directory of Open Access Journals (Sweden)

    Luboš Majeský

    Full Text Available Dandelions (genus Taraxacum comprise a group of sexual diploids and apomictic polyploids with a complicated reticular evolution. Apomixis (clonal reproduction through seeds in this genus is considered to be obligate, and therefore represent a good model for studying the role of asexual reproduction in microevolutionary processes of apomictic genera. In our study, a total of 187 apomictic individuals composing a set of nine microspecies (sampled across wide geographic area in Europe were genotyped for six microsatellite loci and for 162 amplified fragment length polymorphism (AFLP markers. Our results indicated that significant genetic similarity existed within accessions with low numbers of genotypes. Genotypic variability was high among accessions but low within accessions. Clustering methods discriminated individuals into nine groups corresponding to their phenotypes. Furthermore, two groups of apomictic genotypes were observed, which suggests that they had different asexual histories. A matrix compatibility test suggests that most of the variability within accession groups was mutational in origin. However, the presence of recombination was also detected. The accumulation of mutations in asexual clones leads to the establishment of a network of clone mates. However, this study suggests that the clones primarily originated from the hybridisation between sexual and apomicts.

  15. Formation of unreduced megaspores (diplospory) in apomictic dandelions (Taraxacum officinale, s.l.) is controlled by a sex-specific dominant locus.

    Science.gov (United States)

    van Dijk, Peter J; Bakx-Schotman, J M Tanja

    2004-01-01

    In apomictic dandelions, Taraxacum officinale, unreduced megaspores are formed via a modified meiotic division (diplospory). The genetic basis of diplospory was investigated in a triploid (3x = 24) mapping population of 61 individuals that segregated approximately 1:1 for diplospory and meiotic reduction. This population was created by crossing a sexual diploid (2x = 16) with a tetraploid diplosporous pollen donor (4x = 32) that was derived from a triploid apomict. Six different inheritance models for diplospory were tested. The segregation ratio and the tight association with specific alleles at the microsatellite loci MSTA53 and MSTA78 strongly suggest that diplospory is controlled by a dominant allele D on a locus, which we have named DIPLOSPOROUS (DIP). Diplosporous plants have a simplex genotype, Ddd or Dddd. MSTA53 and MSTA78 were weakly linked to the 18S-25S rDNA locus. The D-linked allele of MSTA78 was absent in a hypotriploid (2n = 3x - 1) that also lacked one of the satellite chromosomes. Together these results suggest that DIP is located on the satellite chromosome. DIP is female specific, as unreduced gametes are not formed during male meiosis. Furthermore, DIP does not affect parthenogenesis, implying that several independently segregating genes control apomixis in dandelions. PMID:15020437

  16. Genetic diversity in populations of plants with different breeding and dispersal strategies in a free-flowing boreal river system.

    Science.gov (United States)

    Lundqvist, E; Andersson, E

    2001-01-01

    We have studied the genetic diversity of three plant species: Angelica archangelica (Apiacieae), Bistorta vivipara (Polygonaceae) and Viscaria alpina (Caryophyllaceae) along the free-flowing Vindel River in northern Sweden. The plants differ in reproductive strategy. A archangelica and V. alpina are insect pollinated outbreeders while B. vivipara reproduces with apomixis through bulbils. The seeds of A. archangelica may float for over a year, while the propagules (seeds and bulbils, respectively) of V. alpina and B. vivipara float for less than two days. Genetic diversity was assessed using starch gel electrophoresis. The clonal diversity of B. vivipara measured by Simpson's index (D) ranged between 0.78 and 0.99. Only a few clones were shared between localities. The average percentages polymorphic loci and mean He based on polymorphic loci for V. alpina over all localities were 23.1 and 0.15, respectively. Wright's F-statistics showed a significant overall deficit of heterozygotes. The diversity of A. archangelica was found to increase downstream. Genetic diversity of each species is sufficiently high to be used in studies on hydrochory. Dispersal appears to be related to the floating ability of progagules.

  17. Does polyembryony reduce seed germination and seedling development in Eriotheca pubescens (Malvaceae: Bombacoideae)?

    Science.gov (United States)

    Mendes-Rodrigues, Clesnan; Ranal, Marli A; Oliveira, Paulo E

    2011-10-01

    Competition between siblings affect their growth and survival ability. An extreme situation is polyembryony, whereby siblings are exposed to competition from the beginning of their development. But its effect on plant reproduction is seldom tested. Eriotheca pubescens is a tree in the Cerrado, the Neotropical Savannas in Brazil, with apomictic/polyembryonic and sexual/monoembryonic populations. We tested the effect of polyembryony on germination, emergence, and growth in E. pubescens. This may have ecological consequences within the Cerrado, where seedling establishment is critical for species persistency and distribution. We tested the effect of embryonic origin on germinability- and time-related parameters using seeds from different populations. We measured cultivated seedling growth continuously for 70 d and exhumed them after 9 mo to measure seedling biometry traits such as shoot, root, and seedling mass. We compared these traits with the number of seedlings emerged per seed and fitted data to a linear regression model. Polyembryony reduced germinability and seedlings' initial growth in E. pubescens. Seedling traits and biomass decreased with the number of seedlings arising per seed. But the effect of polyembryony was mostly on initial seedling size and not on seedling growth rate. Polyembryony and apomixis affected germination and led to smaller seedlings compared with monoembryonic sexual counterparts. Although smaller, these extra seedlings may enhance per-seed survival chances in the Cerrado conditions of seasonal drought and frequent fires and explain the predominance of polyembryonic populations.

  18. Explosive pollination mechanism in Periandra mediterranea (Vell. Taub. (Fabaceae in the Guaribas Biological Reserve, Paraíba, Brazil

    Directory of Open Access Journals (Sweden)

    Andressa Cavalcante Meireles

    2015-09-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2015v28n4p71 Periandra mediterranea (Vell. Taub. has papilionaceous flowers with a complex pollination mechanism. This study examined pollination and reproduction in P. mediterranea from November 2009 to October 2011 at the Guaribas Biological Reserve, Paraíba, Brazil. The petals are modified in a keel that protects the stamens and stigma; two wings surround the keel, and a standard that serves as landing platform for floral visitors. Periandra mediterranea exhibits an explosive type pollination mechanism in which the bee species Xylocopa frontalis, Acanthopus excellens and Epicharis sp., land on the standard and, due to body weight, expose the reproductive organs in the wing-keel complex. As a result, the reproductive organs of the flower come into contact with the dorsal region of the bee body, depositing pollen (i.e., nototríbic pollination. Reproductive assays showed 20% fruiting in spontaneous auto-pollination, 33% in manual auto-pollination, 33% in manual cross-pollination, and 100% in the control group, with no reproductive success while in apomixis. These results demonstrate self-compatibility in this species, however it depends on pollinators to ensure reproductive success.

  19. Formation of unreduced megaspores (diplospory) in apomictic dandelions (Taraxacum officinale, s.l.) is controlled by a sex-specific dominant locus.

    Science.gov (United States)

    van Dijk, Peter J; Bakx-Schotman, J M Tanja

    2004-01-01

    In apomictic dandelions, Taraxacum officinale, unreduced megaspores are formed via a modified meiotic division (diplospory). The genetic basis of diplospory was investigated in a triploid (3x = 24) mapping population of 61 individuals that segregated approximately 1:1 for diplospory and meiotic reduction. This population was created by crossing a sexual diploid (2x = 16) with a tetraploid diplosporous pollen donor (4x = 32) that was derived from a triploid apomict. Six different inheritance models for diplospory were tested. The segregation ratio and the tight association with specific alleles at the microsatellite loci MSTA53 and MSTA78 strongly suggest that diplospory is controlled by a dominant allele D on a locus, which we have named DIPLOSPOROUS (DIP). Diplosporous plants have a simplex genotype, Ddd or Dddd. MSTA53 and MSTA78 were weakly linked to the 18S-25S rDNA locus. The D-linked allele of MSTA78 was absent in a hypotriploid (2n = 3x - 1) that also lacked one of the satellite chromosomes. Together these results suggest that DIP is located on the satellite chromosome. DIP is female specific, as unreduced gametes are not formed during male meiosis. Furthermore, DIP does not affect parthenogenesis, implying that several independently segregating genes control apomixis in dandelions.

  20. Sexual polyploidization in plants--cytological mechanisms and molecular regulation.

    Science.gov (United States)

    De Storme, Nico; Geelen, Danny

    2013-05-01

    In the plant kingdom, events of whole genome duplication or polyploidization are generally believed to occur via alterations of the sexual reproduction process. Thereby, diploid pollen and eggs are formed that contain the somatic number of chromosomes rather than the gametophytic number. By participating in fertilization, these so-called 2n gametes generate polyploid offspring and therefore constitute the basis for the establishment of polyploidy in plants. In addition, diplogamete formation, through meiotic restitution, is an essential component of apomixis and also serves as an important mechanism for the restoration of F1 hybrid fertility. Characterization of the cytological mechanisms and molecular factors underlying 2n gamete formation is therefore not only relevant for basic plant biology and evolution, but may also provide valuable cues for agricultural and biotechnological applications (e.g. reverse breeding, clonal seeds). Recent data have provided novel insights into the process of 2n pollen and egg formation and have revealed multiple means to the same end. Here, we summarize the cytological mechanisms and molecular regulatory networks underlying 2n gamete formation, and outline important mitotic and meiotic processes involved in the ectopic induction of sexual polyploidization. © 2013 Ghent University. New Phytologist © 2013 New Phytologist Trust.

  1. Geographical parthenogenesis and population genetic structure in the alpine species Ranunculus kuepferi (Ranunculaceae).

    Science.gov (United States)

    Cosendai, A-C; Wagner, J; Ladinig, U; Rosche, C; Hörandl, E

    2013-06-01

    Geographical parthenogenesis describes the enigmatic phenomenon that asexual organisms have larger distribution areas than their sexual relatives, especially in previously glaciated areas. Classical models suggest temporary advantages to asexuality in colonization scenarios because of uniparental reproduction and clonality. We analyzed population genetic structure and self-fertility of the plant species Ranunculus kuepferi on 59 populations from the whole distribution area (European Alps, Apennines and Corsica). Amplified fragment length polymorphisms (AFLPs) and five microsatellite loci revealed individual genotypes for all populations and mostly insignificant differences between diploid sexuals and tetraploid apomicts in all measures of genetic diversity. Low frequencies of private AFLP fragments/simple sequence repeat alleles, and character incompatibility analyses suggest that facultative recombination explains best the unexpectedly high genotypic diversity of apomicts. STRUCTURE analyses using AFLPs revealed a higher number of partitions and a stronger geographical subdivision for diploids than for tetraploids, which contradicts expectations of standard gene flow models, but indicates a reduction of genetic structure in asexuals. Apomictic populations exhibited high admixture near the sexual area, but appeared rather uniform in remote areas. Bagging experiments and analyses of pollen tube growth confirmed self-fertility for pollen-dependent apomicts, but self-sterility for diploid sexuals. Facultative apomixis combines advantages of both modes of reproduction: uniparental reproduction allows for rapid colonization of remote areas, whereas facultative sexuality and polyploidy maintains genetic diversity within apomictic populations. The density dependence of outcrossing limits range expansions of sexual populations.

  2. A successful crayfish invader is capable of facultative parthenogenesis: a novel reproductive mode in decapod crustaceans.

    Directory of Open Access Journals (Sweden)

    Miloš Buřič

    Full Text Available Biological invasions are impacting biota worldwide, and explaining why some taxa tend to become invasive is of major scientific interest. North American crayfish species, particularly of the family Cambaridae, are prominent invaders in freshwaters, defying the "tens rule" which states that only a minority of species introduced to new regions become established, and only a minority of those become invasive and pests. So far, success of cambarid invaders has largely been attributed to rapid maturation, high reproductive output, aggressiveness, and tolerance to pollution. We provide experimental evidence that females of one cambarid species particularly widespread in Europe, the spiny-cheek crayfish Orconectes limosus, are capable of facultative parthenogenesis. Such reproductive mode has never before been recognized in decapods, the most diverse crustacean order. As shown by analysis of seven microsatellite loci, crayfish females kept physically separated from males produced genetically homogeneous offspring identical with maternal individuals; this suggests they reproduced by apomixis, unlike those females which mated with males and had a diverse offspring. Further research is needed to clarify what environmental conditions are necessary for a switch to parthenogenesis in O. limosus, and what role it plays in natural crayfish populations. However, if such reproductive plasticity is present in other cambarid crayfish species, it may contribute to the overwhelming invasive success of this group.

  3. Apospory appears to accelerate onset of meiosis and sexual embryo sac formation in sorghum ovules

    Directory of Open Access Journals (Sweden)

    Elliott Estella

    2011-01-01

    Full Text Available Abstract Background Genetically unreduced (2n embryo sacs (ES form in ovules of gametophytic apomicts, the 2n eggs of which develop into embryos parthenogenetically. In many apomicts, 2n ES form precociously during ovule development. Whether meiosis and sexual ES formation also occur precociously in facultative apomicts (capable of apomictic and sexual reproduction has not been studied. We determined onset timing of meiosis and sexual ES formation for 569 Sorghum bicolor genotypes, many of which produced 2n ES facultatively. Results Genotype differences for onset timing of meiosis and sexual ES formation, relative to ovule development, were highly significant. A major source of variation in timing of sexual germline development was presence or absence of apomictic ES, which formed from nucellar cells (apospory in some genotypes. Genotypes that produced these aposporous ES underwent meiosis and sexual ES formation precociously. Aposporous ES formation was most prevalent in subsp. verticilliflorum and in breeding lines of subsp. bicolor. It was uncommon in land races. Conclusions The present study adds meiosis and sexual ES formation to floral induction, apomictic ES formation, and parthenogenesis as processes observed to occur precociously in apomictic plants. The temporally diverse nature of these events suggests that an epigenetic memory of the plants' apomixis status exists throughout its life cycle, which triggers, during multiple life cycle phases, temporally distinct processes that accelerate reproduction.

  4. Geographical parthenogenesis and population genetic structure in the alpine species Ranunculus kuepferi (Ranunculaceae)

    Science.gov (United States)

    Cosendai, A-C; Wagner, J; Ladinig, U; Rosche, C; Hörandl, E

    2013-01-01

    Geographical parthenogenesis describes the enigmatic phenomenon that asexual organisms have larger distribution areas than their sexual relatives, especially in previously glaciated areas. Classical models suggest temporary advantages to asexuality in colonization scenarios because of uniparental reproduction and clonality. We analyzed population genetic structure and self-fertility of the plant species Ranunculus kuepferi on 59 populations from the whole distribution area (European Alps, Apennines and Corsica). Amplified fragment length polymorphisms (AFLPs) and five microsatellite loci revealed individual genotypes for all populations and mostly insignificant differences between diploid sexuals and tetraploid apomicts in all measures of genetic diversity. Low frequencies of private AFLP fragments/simple sequence repeat alleles, and character incompatibility analyses suggest that facultative recombination explains best the unexpectedly high genotypic diversity of apomicts. STRUCTURE analyses using AFLPs revealed a higher number of partitions and a stronger geographical subdivision for diploids than for tetraploids, which contradicts expectations of standard gene flow models, but indicates a reduction of genetic structure in asexuals. Apomictic populations exhibited high admixture near the sexual area, but appeared rather uniform in remote areas. Bagging experiments and analyses of pollen tube growth confirmed self-fertility for pollen-dependent apomicts, but self-sterility for diploid sexuals. Facultative apomixis combines advantages of both modes of reproduction: uniparental reproduction allows for rapid colonization of remote areas, whereas facultative sexuality and polyploidy maintains genetic diversity within apomictic populations. The density dependence of outcrossing limits range expansions of sexual populations. PMID:23403961

  5. A successful crayfish invader is capable of facultative parthenogenesis: a novel reproductive mode in decapod crustaceans.

    Science.gov (United States)

    Buřič, Miloš; Hulák, Martin; Kouba, Antonín; Petrusek, Adam; Kozák, Pavel

    2011-01-01

    Biological invasions are impacting biota worldwide, and explaining why some taxa tend to become invasive is of major scientific interest. North American crayfish species, particularly of the family Cambaridae, are prominent invaders in freshwaters, defying the "tens rule" which states that only a minority of species introduced to new regions become established, and only a minority of those become invasive and pests. So far, success of cambarid invaders has largely been attributed to rapid maturation, high reproductive output, aggressiveness, and tolerance to pollution. We provide experimental evidence that females of one cambarid species particularly widespread in Europe, the spiny-cheek crayfish Orconectes limosus, are capable of facultative parthenogenesis. Such reproductive mode has never before been recognized in decapods, the most diverse crustacean order. As shown by analysis of seven microsatellite loci, crayfish females kept physically separated from males produced genetically homogeneous offspring identical with maternal individuals; this suggests they reproduced by apomixis, unlike those females which mated with males and had a diverse offspring. Further research is needed to clarify what environmental conditions are necessary for a switch to parthenogenesis in O. limosus, and what role it plays in natural crayfish populations. However, if such reproductive plasticity is present in other cambarid crayfish species, it may contribute to the overwhelming invasive success of this group.

  6. A Successful Crayfish Invader Is Capable of Facultative Parthenogenesis: A Novel Reproductive Mode in Decapod Crustaceans

    Science.gov (United States)

    Buřič, Miloš; Hulák, Martin; Kouba, Antonín

    2011-01-01

    Biological invasions are impacting biota worldwide, and explaining why some taxa tend to become invasive is of major scientific interest. North American crayfish species, particularly of the family Cambaridae, are prominent invaders in freshwaters, defying the “tens rule” which states that only a minority of species introduced to new regions become established, and only a minority of those become invasive and pests. So far, success of cambarid invaders has largely been attributed to rapid maturation, high reproductive output, aggressiveness, and tolerance to pollution. We provide experimental evidence that females of one cambarid species particularly widespread in Europe, the spiny-cheek crayfish Orconectes limosus, are capable of facultative parthenogenesis. Such reproductive mode has never before been recognized in decapods, the most diverse crustacean order. As shown by analysis of seven microsatellite loci, crayfish females kept physically separated from males produced genetically homogeneous offspring identical with maternal individuals; this suggests they reproduced by apomixis, unlike those females which mated with males and had a diverse offspring. Further research is needed to clarify what environmental conditions are necessary for a switch to parthenogenesis in O. limosus, and what role it plays in natural crayfish populations. However, if such reproductive plasticity is present in other cambarid crayfish species, it may contribute to the overwhelming invasive success of this group. PMID:21655282

  7. Reproductive peculiarities of maize-tripsacum hybrids in connection with the effect of ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yudin, V.F.; Lukina, L.A.; Filippova, T.V. (AN SSSR, Novosibirsk)

    1981-01-01

    The radiation treatment of seeds of highly apomictic forms of maize-tripsacum hybrids (at backcrosses with maize) is not an effective means to increase the yield of reduced hybrids. X-rays and ..gamma..-irradiation (10 kR irradiation dose) were used in the experiments with the highly apomictic form of the hybrid (2n=38). Though about 1.5 thousand plants had been studied only 2 reduced hybrids were found; the first plant was separated in the posterity from ..gamma..-irradiated plants, and the second hybrid - from X-irradiated plants. In the pollination variant which was more widely represented in the experiment ..gamma..-treatment was accompanied by a trustworthy numerical increase of non-reduced hybrids which could be explained by an unequal reaction of apomixis elements to the effect of ..gamma..-radiation: a high stability of the first element - the ability to form non-reduced female gametophytes, and lesser stability of the second element - the ability to parthenogenesis. This is possibly connected with a lower stability of a gene or genes controlling the parthenogenesis but it is excluded that a short-time physiological effect is in the basis of this phenomenon.

  8. Competition between meiotic and apomictic pathways during ovule and seed development results in clonality.

    Science.gov (United States)

    Hojsgaard, Diego H; Martínez, Eric J; Quarin, Camilo L

    2013-01-01

    Meiotic and apomictic reproductive pathways develop simultaneously in facultative aposporous species, and compete to form a seed as a final goal. This developmental competition was evaluated in tetraploid genotypes of Paspalum malacophyllum in order to understand the low level of sexuality in facultative apomictic populations. Cyto-embryology on ovules, flow cytometry on seeds and progeny tests by DNA fingerprinting were used to measure the relative incidence of each meiotic or apomictic pathway along four different stages of the plant's life cycle, namely the beginning and end of gametogenesis, seed formation and adult offspring. A high variation in the frequencies of sexual and apomictic pathways occurred at the first two stages. A trend of radical decline in realized sexuality was then observed. Sexual and apomictic seeds were produced, but the efficiency of the sexual pathway dropped drastically, and exclusively clonal offspring remained. Both reproductive pathways are unstable at the beginning of development, and only the apomictic one remains functional. Key factors reducing sexuality are the faster growth and parthenogenetic development in the aposporous pathway, and an (epi)genetically negative background related to the extensive gene de-regulation pattern responsible for apomixis. The effects of inbreeding depression during post-fertilization development may further decrease the frequency of effective sexuality. No claim to original US government works. New Phytologist © 2012 New Phytologist Trust.

  9. The Full Breadth of Mendel’s Genetics

    Science.gov (United States)

    van Dijk, Peter J.; Ellis, T. H. Noel

    2016-01-01

    Gregor Mendel’s “Experiments on Plant Hybrids” (1865/1866), published 150 years ago, is without doubt one of the most brilliant works in biology. Curiously, Mendel’s later studies on Hieracium (hawkweed) are usually seen as a frustrating failure, because it is assumed that they were intended to confirm the segregation ratios he found in Pisum. Had this been his intention, such a confirmation would have failed, since, unknown to Mendel, Hieracium species mostly reproduce by means of clonal seeds (apomixis). Here we show that this assumption arises from a misunderstanding that could be explained by a missing page in Mendel’s first letter to Carl Nägeli. Mendel’s writings clearly indicate his interest in “constant hybrids,” hybrids which do not segregate, and which were “essentially different” from “variable hybrids” such as in Pisum. After the Pisum studies, Mendel worked mainly on Hieracium for 7 years where he found constant hybrids and some great surprises. He also continued to explore variable hybrids; both variable and constant hybrids were of interest to Mendel with respect to inheritance and to species evolution. Mendel considered that their similarities and differences might provide deep insights and that their differing behaviors were “individual manifestations of a higher more fundamental law.” PMID:27927898

  10. The Full Breadth of Mendel's Genetics.

    Science.gov (United States)

    van Dijk, Peter J; Ellis, T H Noel

    2016-12-01

    Gregor Mendel's "Experiments on Plant Hybrids" (1865/1866), published 150 years ago, is without doubt one of the most brilliant works in biology. Curiously, Mendel's later studies on Hieracium (hawkweed) are usually seen as a frustrating failure, because it is assumed that they were intended to confirm the segregation ratios he found in Pisum Had this been his intention, such a confirmation would have failed, since, unknown to Mendel, Hieracium species mostly reproduce by means of clonal seeds (apomixis). Here we show that this assumption arises from a misunderstanding that could be explained by a missing page in Mendel's first letter to Carl Nägeli. Mendel's writings clearly indicate his interest in "constant hybrids," hybrids which do not segregate, and which were "essentially different" from "variable hybrids" such as in Pisum After the Pisum studies, Mendel worked mainly on Hieracium for 7 years where he found constant hybrids and some great surprises. He also continued to explore variable hybrids; both variable and constant hybrids were of interest to Mendel with respect to inheritance and to species evolution. Mendel considered that their similarities and differences might provide deep insights and that their differing behaviors were "individual manifestations of a higher more fundamental law." Copyright © 2016 van Dijk and Ellis.

  11. FROM ANTHESIS TO DIASPORE DISPERSAL: REPRODUCTIVE MECHANISMS OF RARE HERBACEOUS MORACEAE SPECIES ENDEMIC TO BRAZIL

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    Luzia Márcia de Araújo

    2017-01-01

    Full Text Available Los estudios sobre la biología reproductiva de las especies de Dorstenia son escasos. En este artículo analizamos la sexualidad, la biología floral y dispersión de las diásporas de Dorstenia arifolia y D. bonijesu, incluyendo sus sistemas reproductivos y polinizadores, en poblaciones naturales localizadas en el estado de Minas Gerais, sudeste de Brasil. Registramos, por primera vez, la presencia de cenantos unisexuales (masculinos y bisexuales en un mismo individuo de Dorstenia arifolia; en cambio, sólo se observaron cenantos bisexuales en D. bonijesu. En ambas especies los cenantos fueron de larga duración, y los cenantos bisexuales exhibieron protoginia. Registramos autocompatibilidad y miofilia en Dorstenia arifolia, que fue polinizada por pequeñas moscas de la familia Lauxaniidae. Estos insectos no solo usan el polen como alimento sino que utilizan el cenanto como sitio de oviposición, siendo este un hecho registrado por primera vez para para las especies estudiadas. Dorstenia bonijesu, aún sin visitantes florales, también produce semillas mediante apomixis, un nuevo sistema reproductivo para el género. Las dos especies estudiadas son autocóricas; sin embargo, Dorstenia bonijesu exhibió un tipo peculiar de hidrocoria. Las novedades aquí registradas indican la necesidad de estudios adicionales para mejorar la comprensión de los atributos reproductivos de las especies de Dorstenia.

  12. De novo transcriptome sequencing and assembly from apomictic and sexual Eragrostis curvula genotypes.

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    Ingrid Garbus

    Full Text Available A long-standing goal in plant breeding has been the ability to confer apomixis to agriculturally relevant species, which would require a deeper comprehension of the molecular basis of apomictic regulatory mechanisms. Eragrostis curvula (Schrad. Nees is a perennial grass that includes both sexual and apomictic cytotypes. The availability of a reference transcriptome for this species would constitute a very important tool toward the identification of genes controlling key steps of the apomictic pathway. Here, we used Roche/454 sequencing technologies to generate reads from inflorescences of E. curvula apomictic and sexual genotypes that were de novo assembled into a reference transcriptome. Near 90% of the 49568 assembled isotigs showed sequence similarity to sequences deposited in the public databases. A gene ontology analysis categorized 27448 isotigs into at least one of the three main GO categories. We identified 11475 SSRs, and several of them were assayed in E curvula germoplasm using SSR-based primers, providing a valuable set of molecular markers that could allow direct allele selection. The differential contribution to each library of the spliced forms of several transcripts revealed the existence of several isotigs produced via alternative splicing of single genes. The reference transcriptome presented and validated in this work will be useful for the identification of a wide range of gene(s related to agronomic traits of E. curvula, including those controlling key steps of the apomictic pathway in this species, allowing the extrapolation of the findings to other plant species.

  13. Pollination deficit in open-field tomato crops (Solanum lycopersicum L., Solanaceae in Rio de Janeiro state, Southeast Brazil

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    Mariana Scaramussa Deprá

    2014-02-01

    Full Text Available More than 70% of world’s crops benefit from biotic pollination, and bees are their main pollinators. Despite the fact that some of these insects have been broadly studied, understanding the interactions between plant crops and their pollinators with a local scale approach is necessary when aiming to apply proper protective and management measures to pollinators and their respective crops. In this context, we analyzed the pollination status of open-field tomato crops (Solanum lycopersicum L., regarding fruit-set, visitation rate and the quality of fruits. We recorded the formation of fruits through spontaneous self-pollination and open-pollination, and the occurrence of pollinators in 24 areas of open-field tomato crops. We performed experiments of apomixis, spontaneous self-pollination, manual cross pollination and supplemental cross pollination (simulating the pollinator behavior in a greenhouse. The fruit quality was evaluated according to circumference, weight, volume and number of seeds. Higher production of fruits after open-pollination compared to spontaneous self-pollination indicates the importance of pollinators to increment productivity of S. lycopersicum in the study area. The circumference and the number of seeds from tomatoes of the greenhouse plantation did not differ between spontaneous self-pollination and the manual cross pollination. In the open-field crops the number of seeds was higher for fruits resulting from open-pollination. Our results indicate that the importance of bees is mainly related to the increase in fruit production, thus incrementing the productivity of tomato crops.

  14. Development of innovative techniques and principles that may be used as models to improve plant performance. Technical progress report, February 1, 1990--January 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, W.W.; Burton, G.W.

    1992-06-01

    Methods and techniques for transferring germplasm from wild to cultivated species are being developed. The transferred germplasm is being shown to be valuable in plant breeding and in cultivar development. In the primary gene pool of the grassy Pennisetum glaucum subspecies monodii germplasm, some cytoplasms are being identified that appear to have significant effects on forage yields and morphological characteristics. One cytoplasm, A{sub 4}, is very stable for male sterility and fertility is not easily restored by other lines. It should be a valuable cytoplasm for producing commercial forage hybrids. Disease resistance and yield genes transferred from monodii to cultivated pearl millet lines are having a major impact on increasing production of animals grazing disease resistant Tifleaf 2 pearl millet. Genes controlling resistance to many of the world-wide diseases on pearl millet are being identified in the monodii germplasm. Valuable germplasm has been transferred from the secondary gene pool P. purpuroum) which is used as the pollinator of the first pearl millet grain hybrid in the US Production of 7-chromosome gametes in 42-chromosome interspecific hybrids appears to be genotype specific and makes possible transfer of germplasm from the secondary gene pool to cultivated diploid pearl millet. Significant progress has been made in transferring genes controlling apomixis from P. squamulatum (tertiary gene pool) to cultivated pearl millet. Highly apomictic BC{sub 4} plants have been recovered, one of which sets five times as much seed as the best BC{sub 3} plant.

  15. Marker-assisted screening of breeding populations of an apomictic grass Cenchrus ciliaris L. segregating for the mode of reproduction

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    Suresh Kumar

    2016-12-01

    Full Text Available Cenchrus ciliaris L. is an apomictic forage grass grown in pastures and rangelands of the semi-arid tropics. It reproduces predominantly through apomixis; rarely, obligate sexual plants have also been reported. Absence of sexual reproduction limits the possibility of genetic improvement through hybridization. This study reports on hybridization of an obligate sexual, self- incompatible buffelgrass with pollen from apomictic plants towards development of an F2 population segregating for mode of reproduction and use of sequence characterized amplified region (SCAR markers for screening the population. The segregation ratio of 3:1 (facultative: apomictic was observed in the F1 generation, whereas it was 1:2:1 (apomictic: facultative: sexual in the F2 generation. A number of obligate sexual F2 progenies with desirable agronomic traits were obtained. The SCAR markers were able to screen out apomictic plants from sexual ones, but failed to discriminate between facultative and sexual. Marker-assisted screening could be useful for introgression of desirable trait(s in the apomictic genotype through hybridization.

  16. Construction of BAC libraries from two apomictic grasses to study the microcolinearity of their apospory-specific genomic regions.

    Science.gov (United States)

    Roche, D.; Conner, A.; Budiman, A.; Frisch, D.; Wing, R.; Hanna, W.; Ozias-Akins, P.

    2002-04-01

    We have constructed bacterial artificial chromosome (BAC) libraries from two grass species that reproduce by apospory, a form of gametophytic apomixis. The library of an apomictic polyhaploid genotype (line MS228-20, with a 2C genome size of approximately 4,500 Mbp) derived from a cross between the obligate apomict, Pennisetum squamulatum, and pearl millet ( P. glaucum) comprises 118,272 clones with an average insert size of 82 kb. The library of buffelgrass ( Cenchrus ciliaris, apomictic line B-12-9, with a 2C genome size of approximately 3,000 Mbp) contains 68,736 clones with an average insert size of 109 kb. Based on the genome sizes of these two lines and correcting for the number for false-positive and organellar clones, library coverages were found to be 3.7 and 4.8 haploid genome equivalents for MS 228-20 and B12-9, respectively. Both libraries were screened by hybridization with six SCARs (sequence-characterized amplified regions), whose tight linkage in a single apospory-specific genomic region had been previously demonstrated in both species. Analysis of these BAC clones indicated that some of the SCAR markers are actually amplifying duplicated regions linked in coupling in both genomes and that restriction enzyme mapping will be necessary to sort out the duplications.

  17. A survey of genetic diversity and reproductive biology of Puya raimondii (Bromeliaceae), the endangered queen of the Andes.

    Science.gov (United States)

    Sgorbati, S; Labra, M; Grugni, E; Barcaccia, G; Galasso, G; Boni, U; Mucciarelli, M; Citterio, S; Benavides Iramátegui, A; Venero Gonzales, L; Scannerini, S

    2004-01-01

    Puya raimondii Harms is an outstanding giant rosette bromeliad found solely around 4000 m above sea level in the Andes. It flowers at the end of an 80 - 100-year or even longer life cycle and yields an enormous (4 - 6 m tall) spike composed of from 15,000 to 20,000 flowers. It is endemic and currently endangered, with populations distributed from Peru to the north of Bolivia. A genomic DNA marker-based analysis of the genetic structure of eight populations representative of the whole distribution of P. raimondii in Peru is reported in this paper. As few as 14 genotypes out of 160 plants were detected. Only 5 and 18 of the 217 AFLP marker loci screened were polymorphic within and among these populations, respectively. Four populations were completely monomorphic, each of the others displayed only one to three polymorphic loci. Less than 4 % of the total genomic variation was within populations and genetic similarity among populations was as high as 98.3 %. Results for seven cpSSR marker loci were in agreement with the existence of a single progenitor. Flow cytometry of seed nuclear DNA content and RAPD marker segregation analysis of progeny plantlets demonstrated that the extremely uniform genome of P. raimondii populations is not compatible with agamospermy (apomixis), but consistent with an inbreeding reproductive strategy. There is an urgent need for a protection programme to save not only this precious, isolated species, but also the unique ecosystem depending on it.

  18. Selection of reference genes for quantitative real-time PCR expression studies of microdissected reproductive tissues in apomictic and sexual Boechera

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    Amiteye Samuel

    2011-08-01

    Full Text Available Abstract Background Apomixis, a natural form of asexual seed production in plants, is considered to have great biotechnological potential for agriculture. It has been hypothesised that de-regulation of the sexual developmental pathway could trigger apomictic reproduction. The genus Boechera represents an interesting model system for understanding apomixis, having both sexual and apomictic genotypes at the diploid level. Quantitative qRT-PCR is the most extensively used method for validating genome-wide gene expression analyses, but in order to obtain reliable results, suitable reference genes are necessary. In this work we have evaluated six potential reference genes isolated from a 454 (FLX derived cDNA library of Boechera. RNA from live microdissected ovules and anthers at different developmental stages, as well as vegetative tissues of apomictic and sexual Boechera, were used to validate the candidates. Results Based on homologies with Arabidopsis, six genes were selected from a 454 cDNA library of Boechera: RPS18 (Ribosomal sub protein 18, Efalpha1 (Elongation factor 1 alpha, ACT 2 (Actin2, UBQ (polyubiquitin, PEX4 (Peroxisomal ubiquitin conjugating enzyme and At1g09770.1 (Arabidopsis thaliana cell division cycle 5. Total RNA was extracted from 17 different tissues, qRT-PCRs were performed, and raw Ct values were analyzed for primer efficiencies and gene ratios. The geNorm and normFinder applications were used for selecting the most stable genes among all tissues and specific tissue groups (ovule, anthers and vegetative tissues in both apomictic and sexual plants separately. Our results show that BoechRPS18, BoechEfα1, BoechACT2 and BoechUBQ were the most stable genes. Based on geNorm, the combinations of BoechRPS18 and BoechEfα1 or BoechUBQ and BoechEfα1 were the most stable in the apomictic plant, while BoechRPS18 and BoechACT2 or BoechUBQ and BoechACT2 performed best in the sexual plant. When subgroups of tissue samples were analyzed

  19. Biologia reprodutiva de etnovariedades de mandioca Reproductive biology of cassava landraces

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    Rainério Meireles da Silva

    2001-03-01

    and viability of pollen grains, apomixis, seed production and seed germination of cassava landraces collected in gardens of "caboclos" and Indians of the Amazon region and São Paulo State, both in Brazil. The aspects of the reproductive biology were studied from field evaluations and collection of flower buds and seeds. The experiments were carried out in Piracicaba, SP. Alteration was verified in the floral morphology of the landrace DG-55, which showed hermaphrodite flowers, and DG-65 and variety Mantiqueira, which presented smaller number of ovules per ovary. Honeybee (Apis mellifera was the main pollinator of cassava. There was significant variation in the number and viability of pollen grains. The superior anters of the masculine flower presented, significantly, large number of pollen grains. Apomixis was not detected. A larger number of fruits with two or three seeds were detected. However, seeds originating from fruits with a single seed presented higher germination rates. The morphological alterations in the floral structure influenced the seed production and viability. The variation observed in the aspects of the reproductive biology, was probably due to differentiated selective pressure to which the landraces were submitted along the domestication process.

  20. Processes affecting altitudinal distribution of invasive Ageratina adenophora in western Himalaya: The role of local adaptation and the importance of different life-cycle stages.

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    Arunava Datta

    Full Text Available The spread of invasive plants along elevational gradients is considered a threat to fragile mountain ecosystems, but it can also provide the opportunity to better understand some of the basic processes driving the success of invasive species. Ageratina adenophora (Asteraceae is an invasive plant of global importance and has a broad distribution along elevational gradients in the Western Himalayas. Our study aimed at understanding the role of evolutionary processes (e.g. local adaptation and clinal differentiation and different life history stages in shaping the distribution pattern of the invasive plant along an elevational gradient in the Western Himalaya. We carried out extensive distributional surveys, established a reciprocal transplant experiment with common gardens at three elevational levels, and measured a suite of traits related to germination, growth, reproduction and phenology. Our results showed a lack of local adaptation, and we did not find any evidence for clinal differentiation in any measured trait except a rather weak signal for plant height. We found that seed germination was the crucial life-cycle transition in determining the lower range limit while winter mortality of plants shaped the upper range limit in our study area, thus explaining the hump shaped distribution pattern. Differences in trait values between gardens for most traits indicated a high degree of phenotypic plasticity. Possible causes such as apomixis, seed dispersal among sites, and pre-adaptation might have confounded evolutionary processes to act upon. Our results suggest that the success and spread of Ageratina adenophora are dependent on different life history stages at different elevations that are controlled by abiotic conditions.

  1. Seeds of doubt: Mendel's choice of Hieracium to study inheritance, a case of right plant, wrong trait.

    Science.gov (United States)

    Bicknell, Ross; Catanach, Andrew; Hand, Melanie; Koltunow, Anna

    2016-12-01

    In this review, we explore Gregor Mendel's hybridization experiments with Hieracium , update current knowledge on apomictic reproduction and describe approaches now being used to develop true-breeding hybrid crops. From our perspective, it is easy to conclude that Gregor Mendel's work on pea was insightful, but his peers clearly did not regard it as being either very convincing or of much importance. One apparent criticism was that his findings only applied to pea. We know from a letter he wrote to Carl von Nägeli, a leading botanist, that he believed he needed to "verify, with other plants, the results obtained with Pisum". For this purpose, Mendel adopted Hieracium subgenus Pilosella, a phenotypically diverse taxon under botanical study at the time. What Mendel could not have known, however, is that the majority of these plants are not sexual plants like pea, but instead are facultatively apomictic. In these forms, the majority of seed arises asexually, and such progeny are, therefore, clones of the maternal parent. Mendel obtained very few hybrids in his Hieracium crosses, yet we calculate that he probably emasculated in excess of 5000 Hieracium florets to even obtain the numbers he did. Despite that effort, he was perplexed by the results, and they ultimately led him to conclude that "the hybrids of Hieracium show a behaviour exactly opposite to those of Pisum". Apomixis is now a topic of intense research interest, and in an ironic twist of history, Hieracium subgenus Pilosella has been developed as a molecular model to study this trait. In this paper, we explore further Mendel's hybridization experiments with Hieracium, update current knowledge on apomictic reproduction and describe approaches now being used to develop true-breeding hybrid crops.

  2. The female gametophyte: an emerging model for cell type-specific systems biology in plant development

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    Marc William Schmid

    2015-11-01

    Full Text Available Systems biology, a holistic approach describing a system emerging from the interactions of its molecular components, critically depends on accurate qualitative determination and quantitative measurements of these components. Development and improvement of large-scale profiling methods (omics now facilitates comprehensive measurements of many relevant molecules. For multicellular organisms, such as animals, fungi, algae, and plants, the complexity of the system is augmented by the presence of specialized cell types and organs, and a complex interplay within and between them. Cell type-specific analyses are therefore crucial for the understanding of developmental processes and environmental responses. This review first gives an overview of current methods used for large-scale profiling of specific cell types exemplified by recent advances in plant biology. The focus then lies on suitable model systems to study plant development and cell type specification. We introduce the female gametophyte of flowering plants as an ideal model to study fundamental developmental processes. Moreover, the female reproductive lineage is of importance for the emergence of evolutionary novelties such as an unequal parental contribution to the tissue nurturing the embryo or the clonal production of seeds by asexual reproduction (apomixis. Understanding these processes is not only interesting from a developmental or evolutionary perspective, but bears great potential for further crop improvement and the simplification of breeding efforts. We finally highlight novel methods, which are already available or which will likely soon facilitate large-scale profiling of the specific cell types of the female gametophyte in both model and non-model species. We conclude that it may take only few years until an evolutionary systems biology approach toward female gametogenesis may decipher some of its biologically most interesting and economically most valuable processes.

  3. Overlapping Leaves Covering Flowers in the Alpine Species Eriophyton wallichii (Lamiaceae): Key Driving Factors and Their Potential Impact on Pollination.

    Science.gov (United States)

    Peng, De-Li; Song, Bo; Yang, Yang; Niu, Yang; Sun, Hang

    2016-01-01

    Extrafloral structures are supposed to have evolved to protect flowers from harsh physical environments but might have effects on pollination. Overlapping leaves cover flowers in Eriophyton wallichii, an alpine perennial endemic to the Himalaya-Hengduan Mountains. In previous study, it has showed that these extrafloral leaves can protect interior flowers from temperature fluctuations caused by drastic solar radiation fluctuations, but these leaves may also protect interior flowers from rain wash and UVB damage, and we do not know which one is the main function. In this study, we investigated whether rain and UVB protection are the main functions of overlapping leaves covering flowers and their potential impact on pollination. We first measured the intensities of UVB radiation in open air, beneath leaves and corollas, and then examined pollen susceptibility to different intensities of UVB and rain in the laboratory to estimate whether corollas per se protect interior pollen from UVB and rain damage. We also carried out pollination treatments and observed pollinator visitation of flowers with and without leaves in the field to assess whether the overlapping leaves covering flowers impair pollinator attraction. Our results showed that (1) water and strong UVB significantly decreased pollen germinability, but corollas per se could protect pollen from UVB and rain damage; (2) no autonomous self-pollination and apomixis occurred, and pollinators were essential for the reproduction of E. wallichii; however, flower coverage by overlapping leaves did not limit pollination. We suggested that rain and UVB protection was not the main function of overlapping leaves covered flowers, given that this protection can be provided by corollas per se. Alternatively, this extrafloral structure in E. wallichii may have evolved in response to extreme high temperatures associated with the strong solar radiation fluctuations. This indicates that, even in alpine plants, extreme high

  4. Pollination and breeding system of the enigmatic South African parasitic plant Mystropetalon thomii (Mystropetalaceae): rodents welcome, but not needed.

    Science.gov (United States)

    Hobbhahn, N; Steenhuisen, S-L; Olsen, T; Midgley, J J; Johnson, S D

    2017-09-01

    Unrelated plants adapted to particular pollinator types tend to exhibit convergent evolution in floral traits. However, inferences about likely pollinators from 'pollination syndromes' can be problematic due to trait overlap among some syndromes and unusual floral architecture in some lineages. An example is the rare South African parasitic plant Mystropetalon thomii (Mystropetalaceae), which has highly unusual brush-like inflorescences that exhibit features of both bird and rodent pollination syndromes. We used camera traps to record flower visitors, quantified floral spectral reflectance and nectar and scent production, experimentally determined self-compatibility and breeding system, and studied pollen dispersal using fluorescent dyes. The dark-red inflorescences are usually monoecious, with female flowers maturing before male flowers, but some inflorescences are purely female (gynoecious). Inflorescences were visited intensively by several rodent species that carried large pollen loads, while visits by birds were extremely rare. Rodents prefer male- over female-phase inflorescences, likely because of the male flowers' higher nectar and scent production. The floral scent contains several compounds known to attract rodents. Despite the obvious pollen transfer by rodents, we found that flowers on both monoecious and gynoecious inflorescences readily set seed in the absence of rodents and even when all flower visitors are excluded. Our findings suggest that seed production occurs at least partially through apomixis and that M. thomii is not ecologically dependent on its rodent pollinators. Our study adds another species and family to the growing list of rodent-pollinated plants, thus contributing to our understanding of the floral traits associated with pollination by non-flying mammals. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

  5. Ginger and the beetle: Evidence of primitive pollination system in a Himalayan endemic alpine ginger (Roscoea alpina, Zingiberaceae).

    Science.gov (United States)

    Paudel, Babu Ram; Shrestha, Mani; Dyer, Adrian G; Li, Qing-Jun

    2017-01-01

    The Himalayan endemic alpine genus Roscoea, like other members of ginger family, exhibits the combination of floral traits that would fit pollination by long distant foragers such as bees, birds or flies. We studied the pollination biology of Roscoea alpina, observed potential floral visitors and determined their foraging behaviour, visitation frequency and pollination efficiency, to seek evidence in support of the pollination syndrome hypothesis. We also measured the floral spectra of R. alpina flowers to evaluate if signals fit with the currently known framework for observed floral visitors. We found that R. alpina have autonomous selfing and pollinator-mediated crossing, but lack apomixis. We observed that a beetle (Mylabris sp.), and a moth (Macroglossum nycteris) visit the flowers of R. alpina for pollen and nectar feeding respectively. Our field observations, the stigmatic pollen count and fruit set data indicated that the visit by the beetle was legitimate, while that of the moth was illegitimate. Emasculated flowers visited by beetles set as many fruits and seeds/fruit as auto-selfed and naturally pollinated flowers, while emasculated flowers excluded from beetle visits did not set fruit and seed; indicating that a single visit of a beetle to the flowers of R. alpina can facilitate pollination. We found that flower spectral signal of R. alpina does not fit typical spectra previously reported for beetle or bee-visited flowers. Our results suggest that, to ensure reproductive success in alpine habitat, R. alpina has evolved autonomous selfing as a predominant mode of reproduction, while beetle pollination would promote genetic diversity of this plant species. The visitation of beetles to the flowers of R. alpina, despite floral signal mismatch with the classically associated beetle vision, suggests that a different visual processing may operate in this plant-pollinator interaction at high altitudes.

  6. Detection and analysis of endogenous badnaviruses in the New Zealand flora.

    Science.gov (United States)

    Lyttle, David J; Orlovich, David A; Guy, Paul L

    2011-01-01

    Badnaviruses and their host-integrated DNA occur in tropical crops and a few northern temperate species. Following the discovery of a badnavirus on a subantarctic island with floristic links to New Zealand, we postulated that badnaviruses exist in the New Zealand flora. Badnavirus reverse transcriptase (RT) sequences consist of variable regions flanked by highly conserved regions. This study used RT sequences to detect and characterize badnavirus sequences in the New Zealand flora and to investigate their utility for the study of broader aspects of plant biology. Molecular diversity of RT sequences was analysed using polymerase chain reaction and denaturing gradient gel electrophoresis (DGGE). In a study of the genus Melicytus, internal transcribed spacer (ITS) sequences were compared with the RT data. No freely replicating badnaviruses were detected but more than half of the species (37/60) contained RT sequences. Phylogenetic analysis of 21 RT sequences formed monophyletic groups distinct from other species and from badnaviruses. No frameshift mutations occurred in any of the sequences translated in silico. More detailed study of the genus Melicytus indicated broader applications for our approach. Analysis of RT sequences revealed the presence of a previously unrecognized species (confirmed using ITS). Inheritance of DGGE profiles by Melicytus ramiflorus seedlings suggested that this species may undergo apomixis. The presence of integrated badnavirus sequences in a wide range of taxa from this Southern Hemisphere flora indicates that these sequences may be common in many temperate regions. Potential to activate viruses from these sequences should be considered when placing these species in tissue culture or under other forms of abiotic or genomic stress. Analysis of endogenous RT sequences shows potential for the study of systematics, phylogenetics and plant reproductive biology.

  7. Revisiting the Hetero-Fertilization Phenomenon in Maize

    Science.gov (United States)

    Gao, Shibin; Babu, Raman; Lu, Yanli; Martinez, Carlos; Hao, Zhuanfang; Krivanek, Alan F.; Wang, Jiankang; Rong, Tingzhao; Crouch, Jonathan; Xu, Yunbi

    2011-01-01

    Development of a seed DNA-based genotyping system for marker-assisted selection (MAS) has provided a novel opportunity for understanding aberrant reproductive phenomena such as hetero-fertilization (HF) by observing the mismatch of endosperm and leaf genotypes in monocot species. In contrast to conventional approaches using specific morphological markers, this approach can be used for any population derived from diverse parental genotypes. A large-scale experiment was implemented using seven F2 populations and four three-way cross populations, each with 534 to 1024 individuals. The frequency of HF within these populations ranged from 0.14% to 3.12%, with an average of 1.46%. The highest frequency of HF in both types of population was contributed by the pollen gametes. Using three-way crosses allowed, for the first time, detection of the HF contributed by maternal gametes, albeit at very low frequency (0.14%–0.65%). Four HF events identified from each of two F2 populations were tested and confirmed using 1032 single nucleotide polymorphic markers. This analysis indicated that only 50% of polymorphic markers can detect a known HF event, and thus the real HF frequency can be inferred by doubling the estimate obtained from using only one polymorphic marker. As expected, 99% of the HF events can be detected by using seven independent markers in combination. Although seed DNA-based analysis may wrongly predict plant genotypes due to the mismatch of endosperm and leaf DNA caused by HF, the relatively low HF frequencies revealed with diverse germplasm in this study indicates that the effect on the accuracy of MAS is limited. In addition, comparative endosperm and leaf DNA analysis of specific genetic stocks could be useful for revealing the relationships among various aberrant fertilization phenomena including haploidy and apomixis. PMID:21283522

  8. Population Genetic Structure and Reproductive Strategy of the Introduced Grass Centotheca lappacea in Tropical Land-Use Systems in Sumatra.

    Science.gov (United States)

    Hodač, Ladislav; Ulum, Fuad Bahrul; Opfermann, Nicole; Breidenbach, Natalie; Hojsgaard, Diego; Tjitrosoedirdjo, Sri Sudarmiyati; Vornam, Barbara; Finkeldey, Reiner; Hörandl, Elvira

    2016-01-01

    Intensive transformation of lowland rainforest into oil palm and rubber monocultures is the most common land-use practice in Sumatra (Indonesia), accompanied by invasion of weeds. In the Jambi province, Centotheca lappacea is one of the most abundant alien grass species in plantations and in jungle rubber (an extensively used agroforest), but largely missing in natural rainforests. Here, we investigated putative genetic differentiation and signatures for adaptation in the introduced area. We studied reproductive mode and ploidy level as putative factors for invasiveness of the species. We sampled 19 populations in oil palm and rubber monocultures and in jungle rubber in two regions (Bukit Duabelas and Harapan). Amplified fragment length polymorphisms (AFLP) revealed a high diversity of individual genotypes and only a weak differentiation among populations (FST = 0.173) and between the two regions (FST = 0.065). There was no significant genetic differentiation between the three land-use systems. The metapopulation of C. lappacea consists of five genetic partitions with high levels of admixture; all partitions appeared in both regions, but with different proportions. Within the Bukit Duabelas region we observed significant isolation-by-distance. Nine AFLP loci (5.3% of all loci) were under natural diversifying selection. All studied populations of C. lappacea were diploid, outcrossing and self-incompatible, without any hints of apomixis. The estimated residence time of c. 100 years coincides with the onset of rubber and oil palm planting in Sumatra. In the colonization process, the species is already in a phase of establishment, which may be enhanced by efficient selection acting on a highly diverse gene pool. In the land-use systems, seed dispersal might be enhanced by adhesive spikelets. At present, the abundance of established populations in intensively managed land-use systems might provide opportunities for rapid dispersal of C. lappacea across rural landscapes

  9. Overlapping Leaves Covering Flowers in the Alpine Species Eriophyton wallichii (Lamiaceae: Key Driving Factors and Their Potential Impact on Pollination.

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    De-Li Peng

    Full Text Available Extrafloral structures are supposed to have evolved to protect flowers from harsh physical environments but might have effects on pollination. Overlapping leaves cover flowers in Eriophyton wallichii, an alpine perennial endemic to the Himalaya-Hengduan Mountains. In previous study, it has showed that these extrafloral leaves can protect interior flowers from temperature fluctuations caused by drastic solar radiation fluctuations, but these leaves may also protect interior flowers from rain wash and UVB damage, and we do not know which one is the main function. In this study, we investigated whether rain and UVB protection are the main functions of overlapping leaves covering flowers and their potential impact on pollination. We first measured the intensities of UVB radiation in open air, beneath leaves and corollas, and then examined pollen susceptibility to different intensities of UVB and rain in the laboratory to estimate whether corollas per se protect interior pollen from UVB and rain damage. We also carried out pollination treatments and observed pollinator visitation of flowers with and without leaves in the field to assess whether the overlapping leaves covering flowers impair pollinator attraction. Our results showed that (1 water and strong UVB significantly decreased pollen germinability, but corollas per se could protect pollen from UVB and rain damage; (2 no autonomous self-pollination and apomixis occurred, and pollinators were essential for the reproduction of E. wallichii; however, flower coverage by overlapping leaves did not limit pollination. We suggested that rain and UVB protection was not the main function of overlapping leaves covered flowers, given that this protection can be provided by corollas per se. Alternatively, this extrafloral structure in E. wallichii may have evolved in response to extreme high temperatures associated with the strong solar radiation fluctuations. This indicates that, even in alpine plants

  10. Aspectos da biologia da reprodução em plantas ornamentais cultivadas no Estado de São Paulo: I - Dichorisandra Thyrsiflora Mikan (Commelinaceae Aspects of breeding system of Dichorisancha thyrsiflora Mikan

    Directory of Open Access Journals (Sweden)

    Yone M.S Boaventura

    1987-07-01

    Full Text Available Foram estudados os possíveis sistemas de reprodução em Dichorisandra thyrsiflora. A espécie parece ser predominantemente de fecundação cruzada, embora sem um sistema de autoincompatibilidade definido. Conseqüentemente a autofecundação ocorre numa freqüência bem menor. Quanto à agamospermia, nenhum fruto foi observado em flores não polinizadas. Os agentes polinizadores, invariavelmente, são insetos do gênero Bombus. Observou-se que o número cromossômico da espécie é 2n = 38. A análise da microsporogénese mostrou que a meiose é normal com exceção de algumas células mães de pólen nas quais foi observada a formação de pontes cromatínicas em anáfases I e II, sugerindo existência na população de heterozigotos para inversão. A formação de tétrades normais foi de 95% e a viabilidade dos grãos de pólen foi alta, 87,2%.The breeding system of Dichorisandra thyrsiflora was studied. It was found that this is a mainly cross- pollinated species (92%, without a well defined self-incompatibility mechanism. Self-pollination was obtained in 27% of the analysed flowers, and apomixis was not observed. Pollination agents were mainly of the Bombus genus. The chromosome number of the species was 2n = 38. Microsporogenesis analysis showed normal meiosis, with only a few exceptions, in which chromatic bridges formation was observed in the anaphase I and n, suggesting heterozygosity for the inversion. Normal tetrad formation was 95% and pollen viability was high (87,2%.

  11. Pollen and stomata morphometrics and polyploidy in Eriotheca (Malvaceae-Bombacoideae).

    Science.gov (United States)

    Marinho, R C; Mendes-Rodrigues, C; Bonetti, A M; Oliveira, P E

    2014-03-01

    Approximately 70% of the angiosperm species are polyploid, an important phenomenon in the evolution of those plants. But ploidy estimates have often been hindered because of the small size and large number of chromosomes in many tropical groups. Since polyploidy affects cell size, morphometric analyses of pollen grains and stomata have been used to infer ploidy level. Polyploidy is present in many species of the Cerrado, the Neotropical savanna region in Central Brazil, and has been linked to apomixis in some taxa. Eriotheca gracilipes and Eriotheca pubescens are common tree species in this region, and present cytotypes that form reproductive mosaics. Hexaploid individuals (2n = 6x = 276) are polyembryonic and apomictic, while tetraploid and diploid individuals (2n = 2x = 92, 2n = 4x = 184) are sexual and monoembryonic. We tested whether morphometric analysis can be used to estimate ploidy levels in E. gracilipes and E. pubescens individuals. Pollen material from diploid and hexaploid individuals of E. gracilipes, and tetraploid and hexaploid individuals of E. pubescens, were fixed in 50% FAA, and expanded leaves were dried in silica gel. Pollen grains and stomata of at least five individuals from each population were measured. The results demonstrate that all measures were significantly different among cytotypes. Individuals with higher levels of ploidy (hexaploid) all presented measurements that were higher than those with lower levels (diploid and tetraploid). There was no overlap between ploidy levels in each species at 95% confidence interval. Thus, the size of the pollen grains and stomata are effective parameters for analysis of ploidy levels in E. gracilipes and E. pubescens. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  12. Microsatellite loci for Urochloa decumbens (Stapf) R.D. Webster and cross-amplification in other Urochloa species.

    Science.gov (United States)

    Ferreira, Rebecca C U; Cançado, Letícia J; do Valle, Cacilda B; Chiari, Lucimara; de Souza, Anete P

    2016-03-10

    Forage grasses of the African genus Urochloa (syn. Brachiaria) are the basis of Brazilian beef production, and there is a strong demand for high quality, productive and adapted forage plants. Among the approximately 100 species of the genus Urochloa, Urochloa decumbens is one of the most important tropical forage grasses used for pastures due to several of its agronomic attributes. However, the level of understanding of these attributes and the tools with which to control them at the genetic level are limited, mainly due to the apomixis and ploidy level of this species. In this context, the present study aimed to identify and characterize molecular microsatellite markers of U. decumbens and to evaluate their cross-amplification in other Urochloa species. Microsatellite loci were isolated from a previously constructed enriched library from one U. decumbens genotype. Specific primers were designed for one hundred thirteen loci, and ninety-three primer pairs successfully amplified microsatellite regions, yielding an average of 4.93 alleles per locus. The polymorphism information content (PIC) values of these loci ranged from 0.26 to 0.85 (average 0.68), and the associated discriminating power (DP) values ranged from 0.22 to 0.97 (average 0.77). Cross-amplification studies demonstrated the potential transferability of these microsatellites to four other Urochloa species. Structure analysis revealed the existence of three distinct groups, providing evidence in the allelic pool that U. decumbens is closely related to Urochloa ruziziensis and Urochloa brizantha. The genetic distance values determined using Jaccard's coefficient ranged from 0.06 to 0.76. The microsatellite markers identified in this study are the first set of molecular markers for U. decumbens species. Their availability will facilitate understanding the genetics of this and other Urochloa species and breeding them, and will be useful for germplasm characterization, linkage mapping and marker

  13. Floral Biology and Hybridization Potential of Nine Accessions of Physic Nut Jatropha curcas L. originating from Three Continents

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    Ahoton, LE.

    2012-01-01

    Full Text Available Jatropha curcas is a shrub which has an important economic and medicinal role in tropical and subtropical zones of the world. The oil of its kernels can serve as fuel feedstock to produce diesel, indicating its potential as a renewable source of energy. In an attempt to introduce new variation into cultivated Jatropha curcas, a program of intraspecific hybridization with several ecotypes originating from Africa, Asia and America was undertaken. Field studies were performed over three years 2009, 2010 and 2011. Before achieving hybridization, the floral ratio and the breeding system of physic nut were studied in Southern Benin ecological conditions. Significant differences (P< 0.05 were observed between the analysed ecotypes regarding the number of female flowers. This study has also confirmed that the breeding system of Jatropha curcas is essentially outcrossing and that foraging insects are the main pollination actors of female flowers. New intraspecific hybrid combinations were produced involving nine accessions. Crosses results varied according to the origin and the direction of the hybridization. Crosses between accessions of J. curcas originating from Africa and Asia gave hybrids without difficulty. The data obtained confirm that apomixis might play a major role in J. curcas a reproductive biology. Considering the high number of female flowers per inflorescence produced by the accession from Ecuador, and the large genetic distance existing between this accession and those from Africa and Asia, it should constitute a valuable genetic stock for the development of F1 hybrids with local ecotypes of J. curcas. However, the use of growth regulators might be necessary to improve the hybridization success rate when it is used as female parent.

  14. Processes affecting altitudinal distribution of invasive Ageratina adenophora in western Himalaya: The role of local adaptation and the importance of different life-cycle stages.

    Science.gov (United States)

    Datta, Arunava; Kühn, Ingolf; Ahmad, Mustaqeem; Michalski, Stefan; Auge, Harald

    2017-01-01

    The spread of invasive plants along elevational gradients is considered a threat to fragile mountain ecosystems, but it can also provide the opportunity to better understand some of the basic processes driving the success of invasive species. Ageratina adenophora (Asteraceae) is an invasive plant of global importance and has a broad distribution along elevational gradients in the Western Himalayas. Our study aimed at understanding the role of evolutionary processes (e.g. local adaptation and clinal differentiation) and different life history stages in shaping the distribution pattern of the invasive plant along an elevational gradient in the Western Himalaya. We carried out extensive distributional surveys, established a reciprocal transplant experiment with common gardens at three elevational levels, and measured a suite of traits related to germination, growth, reproduction and phenology. Our results showed a lack of local adaptation, and we did not find any evidence for clinal differentiation in any measured trait except a rather weak signal for plant height. We found that seed germination was the crucial life-cycle transition in determining the lower range limit while winter mortality of plants shaped the upper range limit in our study area, thus explaining the hump shaped distribution pattern. Differences in trait values between gardens for most traits indicated a high degree of phenotypic plasticity. Possible causes such as apomixis, seed dispersal among sites, and pre-adaptation might have confounded evolutionary processes to act upon. Our results suggest that the success and spread of Ageratina adenophora are dependent on different life history stages at different elevations that are controlled by abiotic conditions.

  15. Phylogenetic origin of limes and lemons revealed by cytoplasmic and nuclear markers.

    Science.gov (United States)

    Curk, Franck; Ollitrault, Frédérique; Garcia-Lor, Andres; Luro, François; Navarro, Luis; Ollitrault, Patrick

    2016-04-01

    . meyeri). Among triploid limes, C. latifolia accessions ('Tahiti' and 'Persian' lime types) result from the fertilization of a haploid ovule of C. limon by a diploid gamete of C. aurantifolia, while C. aurantifolia triploid accessions ('Tanepao' lime types and 'Madagascar' lemon) probably result from an interspecific backcross (a diploid ovule of C. aurantifolia fertilized by C. medica). As limes and lemons were vegetatively propagated (apomixis, horticultural practices) the intra-sub-group phenotypic diversity results from asexual variations. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Complex history of admixture during citrus domestication revealed by genome analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wu, G. Albert; Prochnik, Simon; Jenkins, Jerry; Salse, Jerome; Hellsten, Uffe; Murat, Florent; Perrier, Xavier; Ruiz, Manuel; Scalabrin, Simone; Terol, Javier; Takita, Marco Aur& #233; lio,; Labadie, Karine; Poulain, Julie; Couloux, Arnaud; Jabbari, Kamel; Cattonaro, Federica; Fabbro, Cristian Del; Pinosio, Sara; Zuccolo, Andrea; Chapman, Jarrod; Grimwood, Jane; Tadeo, Francisco; Estornell, Leandro H.; Mu?oz-Sanz, Juan V.; Ibanez, Victoria; Herrero-Ortega, Amparo; Aleza, Pablo; P& #233; rez, Juli& #225; n P& #233; rez,; Ramon, Daniel; Brunel, Dominique; Luro, Francois; Chen, Chunxian; Farmerie, William G.; Desany, Brian; Kodira, Chinnappa; Mohiuddin, Mohammed; Harkins, Tim; Fredrikson, Karin; Burns, Paul; Lomsadze, Alexandre; Borodovsky, Mark; Reforgiato, Giuseppe; Freitas-Astua, Juliana; Quetier, Francis; Navarro, Luis; Roose, Mikeal; Wincker, Patrick; Schmutz, Jeremy; Morgante, Michele; Machado, Marcos Antonio; Talon, Manuel; Jaillon, Olivier; Ollitrault, Patrick; Gmitter, Frederick; Rokhsar, Daniel

    2014-06-30

    vulnerable to disease outbreaks, including citrus greening disease (also known as Huanglongbing) that is rapidly spreading throughout the world's major citrus producing regions1. Understanding the population genomics and domestication of citrus will enable strategies for improvements to citrus including resistance to greening and other diseases. The domestication and distribution of edible citrus types began several thousand years ago in Southeast Asia and spread globally following ancient land and sea routes. The lineages that gave rise to most modern cultivated varieties, however, are lost in undocumented antiquity, and their identities remain controversial2, 3. Several features of Citrus biology and cultivation make deciphering these origins difficult. Cultivated varieties are typically propagated clonally by grafting and through asexual seed production (apomixis via nucellar polyembryony) to maintain desirable combinations of traits (Fig. 1). Thus many important cultivar groups have characteristic basic genotypes that presumably arose through interspecific hybridization and/or successive introgressive hybridizations of wild ancestral species. These domestication events predated the global expansion of citrus cultivation by hundreds or perhaps thousands of years, with no record of the domestication process. Diversity within such groups arises through accumulated somatic mutations, generally without sexual recombination, either as limb sports on trees or variants among apomictic seedling progeny. Two wild species are believed to have contributed to domesticated pummelos, mandarins and oranges. Based on morphology and genetic markers, pummelos have generally been identified with the wild species C. maxima (Burm.) Merrill that is indigenous to Southeast Asia. Although mandarins are similarly widely identified with the species C. reticulata Blanco 4-6, wild populations of C. reticulata have not been definitively described. Various authors have taken dif

  17. Microsporogenesis in Brachiaria bovonei (Chiov. Robyns and B. subulifolia (Mez Clayton (Poaceae Microsporogênese em Brachiaria bovonei (Chiov. Robyns e B. subulifolia (Mez Clayton (Poaceae

    Directory of Open Access Journals (Sweden)

    Claudicéia Risso-Pascotto

    2009-10-01

    Full Text Available Some African species of Brachiaria have been introduced into the Americas and became the most important forage for pastures in the tropics. New cultivars can be obtained either from direct selections from the natural existing variability in the germplasm collections or from interspecific hybridizations. Polyploidy is predominant in the genus Brachiaria and correlated with apomixis which complicates hybridization. The objective of cytological studies underway on the Brachiaria germplasm collection at Embrapa Beef Cattle is to determine the chromosome number and meiotic behavior of accessions. For the breeding of Brachiaria species, compatible sexual and apomictic accessions need to be identified. Microsporogenesis was evaluated in two accessions of Brachiaria bovonei (BO01 and BO05 and one accession of B. subulifolia (SU01. BO01 is pentaploid (2n = 5x = 45, BO05 is tetraploid (2n = 4x = 36, and SU01 is hexaploid (2n = 6x = 54, derived from x = 9. Meiotic abnormalities typical of polyploids, characterized by precocious chromosome migration to the poles in metaphases, laggard chromosomes in anaphases, and micronuclei in telophases and tetrads, were recorded in high frequency in all the accessions generating unbalanced gametes. Both accessions of B. bovonei presented chromosome stickiness. The results are discussed in the view of the Brachiaria breeding program objectives.Algumas espécies africanas de Brachiaria foram introduzidas nas Américas e tornaram-se importantes pastagens nos trópicos. Novas cultivares podem ser obtidas por seleção direta da variabilidade genética existente na coleção de germoplasma ou por hibridização interespecífica. Poliploidia é predominante no gênero Brachiaria e correlacionada com apomixia, o que complica a hibridização. O objetivo dos estudos citogenéticos na coleção de germoplasma de Brachiaria da Embrapa Gado de Corte é determinar o número de cromossomos e o comportamento meiótico dos acessos. A

  18. Determinação do modo de reprodução em capim-gordura (Melinis minutiflora Beauv. por padrões enzimáticos Detection of the mode of reproduction in molasses grass (Melinis minutiflora Beauv. by enzyme patterns

    Directory of Open Access Journals (Sweden)

    Lia Rejane Machado Silveira

    1996-04-01

    , leucine aminopeptidases and malato dehydrogenases of the parental generations with their offsprings. The high uniformity of patterns obtained in the offsprings, the identical patterns found for both the female parents and their respectives progenies and also the presence of banding patterns, characteristically shown by heterozygotes of the leucine aminopeptidase and malato dehydrogenase systems, are strong evidences for the hypothesis of apomictic reproduction in this species. In addiction, the isozymatic segregation for acid phosphatase observed in plants of CG4 and CG5 ecotypes and the detection of hybrids from CG2 x CG3 crosses, are indicating that the apomixis in molasses grass is facultative.

  19. Sistema reprodutivo e diversidade genética de quatro espécies de Myrciaria (Myrtaceae, jabuticabeiras Reproductive system and genetic diversity of four species of Myrciaria (Myrtaceae, jabuticabeiras

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    Regina Célia Freitas Vilela

    2012-12-01

    cross-pollination treatments between M. trunciflora x M. cauliflora and M. jaboticaba x M. coronata in order to identify possible postzygotic reproductive isolation mechanisms, and c relate the genetic distance of these species and 14 other taxa preserved ex situ, by RAPD molecular markers. The reproductive treatments showed that jaboticaba are self-compatible species and no apomixis was found in these species. The bi-directional cross-pollinations between M. trunciflora x M. cauliflora, and between M. jaboticaba x M. coronata, generated fruit production that ranged from 22 to 27%, and their seeds produced healthy plants, demonstrating the lack of genetic barriers between these species, as well as immature fruit dropping. Such compatibility of interbreeding can be explored in genetic improvements aimed at the transfer of traits of interest in agronomically superior genotypes. A low degree of genetic differentiation was found among the different taxa, suggesting that the genetic similarity observed is not compatible with the morphological similarity and the main taxonomic characters are polymorphic within the genus.

  20. Ecologia da polinização de Raphiodon echinus (Nees & Mart. Schauer (Lamiaceae em Petrolina, PE, Brasil Pollination ecology of Raphiodon echinus (Nees & Mart. Schauer (Lamiaceae in Petrolina, Pernambuco State, Brazil

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    Carla Tatiana de Vasconcelos Dias

    2007-12-01

    Full Text Available Raphiodon echinus é uma espécie de hábito rasteiro, que ocorre espontaneamente em áreas de caatinga. No presente trabalho foram observados a biologia reprodutiva desta espécie com o objetivo de contribuir com informações sobre sua ecologia da polinização. As observações foram feitas em áreas de caatinga da Embrapa Semi-Árido, em Petrolina, PE. Para os experimentos de autopolinização espontânea, autopolinização manual, apomixia, geitonogamia, xenogamia, botões foram ensacados, emasculados e polinizados, quando necessário. Flores foram marcadas para estimar a polinização em condições naturais. Os visitantes florais foram observados das 7h30 min às 16h00, totalizando 45 horas de observações. As flores de R. echinus são infundibuliformes, de coloração violeta, exalam odor adocicado e estão reunidas em glomérulos. A antese é diurna, assincrônica, sendo mais freqüente no período da manhã, por volta das 07h00. A duração das flores é de aproximadamente 10 horas e cada inflorescência apresenta número variado de flores/dia. As flores são visitadas por abelhas e borboletas. Centris hyptidis foi responsável por 26% do total das visitas e, de acordo com o comportamento e freqüência de visitas, foi considerada como polinizador efetivo desta espécie. Quanto ao sistema de reprodução, R. echinus é autógama facultativa, produzindo frutos por autopolinização manual (70%, geitonogamia (63% e xenogamia (40%.Raphiodon echinus is a prostrate weedy species that occurs in the Caatinga. In this work, floral biology and reproductive system were observed in order to understand the pollination ecology of this species. Observations were made at Embrapa Semi-Árido, in Petrolina, Pernambuco. For the self-pollination, apomixis, geitonogamy and xenogamy experiments, buds were protected, emasculated, and pollinated when necessary. Flowers were tagged to estimate pollination success under natural conditions. Floral visitors