How common is self-incompatibility across species of the herkogamous genus Ariocarpus?

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作   者：

Martinez-Peralta, C.;  Marquez-Guzman, J.;  Mandujano, M. C.; 

作者机构：

D. F.;  Facultad de Ciencias;  Departamento de Biolog Comparada;  Universidad Nacional Automa de Mcico 04510;  Departamento de Ecolog de la Biodiversidad;  Ciudad Universitaria;  Instituto de Ecolog;  Laboratorio de Genica y Ecolog;  Apartado Postal 70-275;  Mcico;  Universidad Nacional Automa de Mcico;  Laboratorio de Desarrollo en Plantas; 

关键词：

Cactaceae;  self-incompatibility;  natural populations;  Ariocarpus;  partial self-incompa-ibility;  hand-pollination treatments;  pollen tube growth;  endemic species; 

期刊名称：

American journal of botany

i s s n：

0002-9122

年卷期：

2014 年 101 卷 3 期

页   码：

530-538

页   码：

摘   要：

Premise of the study: Self-incompatibility (SI), the most effective mechanism to prevent selfing, may limit the number of compatible mates in populations. The seven species of Ariocarpus are endangered and predominantly outcrossers but fruit set may reach 1-20% after selfing. We aimed to determine whether SI is the underlying mechanism influencing mating in Ariocarpus species. Methods: We characterized the presence/absence of SI using pollination treatments (self-pollination, cross-pollination, natural pollination) in one population per species. We assessed SI using epifluorescence and generalized linear models (GLMs) to compare the presence of pollen tubes in the stigma, stylar transmitting tissue, and ovary among self- and cross-pollinated pistils 48 h after pollination. Following the same treatments, production of fruit set was noted and related to pollen tube growth. Key results: Pollen tubes were found more frequently in the ovaries of natural and cross-pollinated flowers than in ovaries of self-pollinated. Stylar rejection of self-pollen indicated gametophytic SI, although pollen tubes reached the ovaries in six species (4-33% of pistils). Fruit set was lower after hand-pollinations than expected from pollen tube observations. Conclusions: The low percentages of self-compatibility in all species in pollen tube growth and pollination experiments indicated that no species had complete self-sterility, suggesting the presence of partial SI. Reduced fruit set relative to pollen tube production could result from a threshold of insufficient pollination, early-acting inbreeding depression, or resource limitation. The origin of partial SI in Ariocarpus could respond to pressures such as pollen limitation and population size.