The occurrence of gynodioecy among angiosperms appears to be associated with self-compatibility. We use individual-based simulations to investigate the conditions for breakdown of a gametophytic self-incompatibility system in gynodioecious populations and make a comparison with hermaphroditic populations where the conditions are well known. We study three types of mutations causing self-compatibility. We track the fate of these mutations in both gynodioecious and hermaphroditic populations, where we vary the number of S-alleles, inbreeding depression and selfing rate. We find that the conditions for breakdown are less stringent if the population is gynodioecious and that the breakdown of self-incompatibility tends to promote stability of gynodioecious populations since it results in a higher frequency of females. We also find that fecundity selection has a large effect on the probability of breakdown of self-incompatibility, in particular if caused by a mutation destroying the female function of the S-locus.
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http://dx.doi.org/10.1017/S0016672307009007 | DOI Listing |
New Phytol
December 2024
Department of Biological Sciences, Clemson University, Clemson, SC, 29634, USA.
Mate limitation in small populations can reduce reproductive fitness, hinder population growth, and increase extinction risk. Mate limitation is exacerbated in self-incompatible (SI) taxa, where shared S-alleles further restrict mating. Theory suggests genetic drift as a predictor of mate limitation and the breakdown of SI systems.
View Article and Find Full Text PDFGenome Biol Evol
December 2024
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku 113-0033, Tokyo, Japan.
Self-incompatibility (SI) is a genetic mechanism to prevent self-fertilization and thereby promote outcrossing in hermaphroditic plant species through discrimination of self and nonself-pollen by pistils. In many SI systems, recognition between pollen and pistils is controlled by a single multiallelic locus (called the S-locus), in which multiple alleles (called S-alleles) are segregating. Because of the extreme level of polymorphism of the S-locus, identification of S-alleles has been a major issue in many SI studies for decades.
View Article and Find Full Text PDFAm J Bot
December 2024
Agroécologie, INRAE, Institut Agro, Université Bourgogne, Université Bourgogne Franche-Comté, Dijon, F-21000, France.
Premise: Restoration of seminatural field margins can elevate pollinator activity. However, how they support wild plant gene flow through interactions between pollinators and spatiotemporal gradients in floral resources remains largely unknown.
Methods: Using a farm-scale experiment, we tested how mating outcomes (expected heterozygosity and paternity correlation) of the wild, self-incompatible plant Cyanus segetum transplanted into field margins (sown wildflower or grass-legume strips) were affected by the abundance of different pollinator functional groups (defined by species traits).
Backcrossing between Sikitita and its male parent Arbequina, offers the possibility to check the suitability of different self-incompatibility models proposed for olive. To determine Sikitita's response to self- and cross-pollination treatments, including pollination with its father Arbequina, we compared the parameters following pollen-pistil interaction, the resulting initial and final fruit set, and the paternity of the seeds produced under different crosses. The results showed that Sikitita behaves as a self-incompatible cultivar due to the inhibition of pollen tube growth in the pistil of self-pollinated flowers.
View Article and Find Full Text PDFPlant Mol Biol
October 2024
Division of Apple Research, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization, 92-24 Nabeyashiki, Shimokuriyagawa, Morioka, Iwate, 020-0123, Japan.
Although self-incompatibility in apples (Malus × domestica Borkh.) is regulated by a single S-locus with multiple S-haplotypes that comprise pistil S (S-RNase) and pollen S genes, it is not desirable in commercial orchards because it requires cross-pollination to achieve stable fruit production. Therefore, it is important to identify and characterize self-compatible apple cultivars.
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