Conceição Sofia I R, Fernandes Joana, Borges da Silva Elsa, Caperta Ana D
Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
Forest Research Centre (CEF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
Plants (Basel). 2021 Jan 17;10(1):169. doi: 10.3390/plants10010169.
Ex situ plant collections established from seeds of natural populations are key tools for understanding mating systems of intricate taxonomic complexes, as in the Mill. genus (sea lavenders, Plumbaginaceae). Plants show a polymorphic sexual system associated to flower polymorphisms such as ancillary pollen and stigma and/or heterostyly that prevents self and intramorph mating. The main objectives of this study were to investigate the significance of pollen-stigma dimorphisms and the role of flower visitors in the reproductive output of hybrids arising from sexual diploids of complex and apomicts tetraploids of complex in an open cross-pollination experiment. Results showed that, similarly to parental plants, hybrids present inflorescence types, self-incompatible flowers, and produced regular pollen grains with the typical exine patterns, with medium to high viability. By contrast, apomicts show floral polymorphisms, inflorescences, and pollen grains of maternal phenotype but with low stainability. Several insects' species visited the inflorescences of parental plants and both hybrids and apomicts and some of these insects carried A and/or B pollen grains on their bodies, especially (Rebel) and sp. Insects' floral visits to hybrids and apomicts seem to be independent of pollen fertility and plants' reproductive modes. Both hybrids and apomicts were able to produce fertile seeds, although the latter showed more seedlings with developmental anomalies than the first plants. The findings demonstrate that there is a weak reproductive barrier between the diploid species of complex as they can hybridize and produce fertile hybrids, provided there is pollen transport by pollinator insects. This study supports that apomixis is a strong reproductive barrier between both and complexes but did not allow us to exclude reproductive interferences of apomict pollen into sexuals.
从自然种群种子建立的迁地植物收集是理解复杂分类群交配系统的关键工具，如补血草属（匙叶草属，蓝雪科）。植物表现出与花的多态性相关的多态性性系统，如辅助花粉和柱头以及/或花柱异长，可防止自交和同型交配。本研究的主要目的是在开放异花授粉实验中，研究花粉 - 柱头二态性的意义以及访花者在由复杂的有性二倍体和复杂的无融合生殖四倍体产生的杂种的繁殖输出中的作用。结果表明，与亲本植物类似，杂种呈现花序类型、自交不亲和的花，并产生具有典型外壁图案、活力中等至高的正常花粉粒。相比之下，无融合生殖体表现出母本表型的花多态性、花序和花粉粒，但染色性低。几种昆虫访问亲本植物以及杂种和无融合生殖体的花序，其中一些昆虫身上携带A和/或B花粉粒，尤其是[某种昆虫名称1]（雷贝尔）和[某种昆虫名称2]属。昆虫对杂种和无融合生殖体的访花似乎与花粉育性和植物的繁殖方式无关。杂种和无融合生殖体都能够产生可育种子，尽管后者比前者表现出更多发育异常的幼苗。研究结果表明，复杂的二倍体物种之间存在较弱的生殖障碍，因为它们可以杂交并产生可育杂种，前提是有传粉昆虫进行花粉传播。本研究支持无融合生殖是复杂的[物种名称1]和[物种名称2]之间的强大生殖障碍，但不允许我们排除无融合生殖花粉对有性生殖体的生殖干扰。
