The Breeding Systems of Six Species of Arabis (Brassicaceae)

Roy, Barbara A.

doi:10.2307/2445973

Cited by 55 publications

(81 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Sexual and apomictic development in A. holboellii have been described cytologically in great detail by Böcher (1951). Evidence for apomixis at the molecular level has also been described (Roy and Rieseberg 1989;Roy 1995).…”

Section: Introductionmentioning

confidence: 80%

Reproductive development in apomictic populations of Arabis holboellii (Brassicaceae)

et al. 2001

View full text Add to dashboard Cite

Megasporogenesis, megagametogenesis and seed formation were analyzed cytologically in populations of Arabis holboellii originating from North America (Colorado) and Greenland. The Colorado population contained only triploid plants, while the Greenland population consisted of diploid and triploid plants. The penetrance of the apomictic trait was assessed at the level of embryo sac development. All populations showed facultative apomeiotic embryo sac development; however the penetrance of this trait differed between the populations. Apomeiotic and meiotic embryo sac development were characterized by diplosporous dyad formation (Taraxacum-type) and meiotic tetrad formation (Polygonum-type), respectively. Flow cytometric analyses of single mature seeds from all three populations suggest that only unreduced gametes participate in viable seed development. Pseudogamy was the predominant mode of endosperm formation; however, autonomous endosperm development was also observed. The fertilization of unreduced egg cells with unreduced pollen was observed at a low frequency in the Greenland populations. The mechanisms of apomictic reproduction in A. holboellii are discussed.

show abstract

Section: Introductionmentioning

confidence: 80%

Reproductive development in apomictic populations of Arabis holboellii (Brassicaceae)

et al. 2001

View full text Add to dashboard Cite

show abstract

“…Reproduction in this species is entirely by seeds; the plants are tap-rooted and do not spread vegetatively. The populations under study are pseudogamously apomictic; that is, pollen is necessary for successful seed set but does not fertilize the ovules (Roy 1995). Because seed production is apomictic, all progeny produced by an individual are genetically identical (Roy and Rieseberg 1989).…”

Section: Methodsmentioning

confidence: 99%

“…The Arabis-rust system does not appear to ®t this theoretical ®nding either. The pathogen should be a better disperser because it is windborne, whereas the host migrates mostly through seeds (pollen can be discounted as a primary source of gene¯ow as these plants are pseudogamous ± pollen is required to initiate seed set, but does not fertilize the egg; Roy 1995). Under these circumstances, when the pathogen migrates faster than the host, the pathogen ought to be locally adapted, not the host (Gandon et al 1996).…”

Section: Local Adaptationmentioning

confidence: 99%

“…This kind of selection decreases diversity, so why is there clonal diversity at these sites? One answer may be that occasional sexual reproduction leads to the generation of new clones when apomictic pollen crosses with sexual individuals (Roy and Rieseberg 1989;Roy 1995). These events are not likely to be common, however, as electrophoretic surveys of more than 1200 individuals at these sites revealed only a single plant that was likely to be sexual (Roy 1993b, and unpublished work).…”

Section: Rarity Advantagementioning

confidence: 99%

See 1 more Smart Citation

Differentiating the effects of origin and frequency in reciprocal transplant experiments used to test negative frequency-dependent selection hypotheses

Roy

1998

Oecologia

Self Cite

View full text Add to dashboard Cite

Reciprocal transplant experiments have been used to estimate the probability that negative frequency-dependent selection by natural enemies has occurred in host populations by determining whether pest populations are less adapted to "foreign" (rare) hosts, which originate from a population with which the pests have not coevolved. However, these experiments usually confound the effects of frequency and origin: the rare genotypes are also genotypes that did not originate at a site. When clonal organisms are used, and the clones occur in more than one population, it is possible to separate the effects of origin and frequency. Here I present the results of an experiment in which Arabis clones of known frequency were reciprocally transplanted among sites. Contrary to expectations, clones at their site of origin had less disease, less herbivory, and higher fitness than foreign clones. However, variation within and among sites in herbivory and infection was large, suggesting that the number of sites and clones needed to thoroughly test the hypothesis of negative frequency-dependent selection in this system is very large: thus, these results are suggestive but not conclusive.

show abstract

“…The basic chromosome number of B. holboellii is 7, and polyploidy (typically 3x) and B chromosomes are common (Sharbel et al 2005). In this work, we used triploid B. holboellii and B. gunnisoniana accessions (Roy 1995) that were previously reported as a facultative diplosporous (Taraxacum type) apomicts (Naumova et al 2001, Taskin et al 2004) and diploid apomict B. divaricarpa (Schranz et al 2005). Flow cytometric analysis of mature seeds from the triploid species showed that pseudogamy is predominant and that only the unreduced female and male gametes contribute to mature seed (Naumova et al 2001, Taskin et al 2004).…”

Section: Resultsmentioning

confidence: 99%

Apomeiotic pollen mother cell development in the apomictic Boechera species

Taşkın¹,

Turgut²,

Scott³

2009

Biol. plant.

View full text Add to dashboard Cite

Pollen mother cell (PMC) development in the apomictic Boechera species B. holboellii, B. gunnisoniana and B. divaricarpa were investigated by various cytological methods. In prophase I, in triploid species B. holboellii and B. gunnisoniana the individual chromosomes condensed into long strands within the nucleus. Then, in metaphase I, each PMC formed a restitutional nucleus thereby bypassing the rest of the first meiotic division. This is interpreted as representing apomeiosis. Subsequently, the restitution nuclei underwent a single cytokinesis as evidenced by the production of dyads. The cells within each dyad were separated by a callose wall. Most of the PMC in B. holboellii and B. gunnisoniana produced dyads, but a small proportion generated conspicuous tetrads. In contrast, diploid apomict B. divaricarpa produced only tetrads by simultaneous cytokinesis.Additional key word: apomixis, endosperm, male gametes.

show abstract

The Breeding Systems of Six Species of Arabis (Brassicaceae)

Cited by 55 publications

References 0 publications

Reproductive development in apomictic populations of Arabis holboellii (Brassicaceae)

Reproductive development in apomictic populations of Arabis holboellii (Brassicaceae)

Differentiating the effects of origin and frequency in reciprocal transplant experiments used to test negative frequency-dependent selection hypotheses

Apomeiotic pollen mother cell development in the apomictic Boechera species

Contact Info

Product

Resources

About