Data from: Experimental insights on the function of ancillary pollen and stigma polymorphisms in plants with heteromorphic incompatibility

Most heterostylous plants possess a reciprocal arrangement of stigmas and anthers (reciprocal herkogamy), heteromorphic self-incompatibility and ancillary polymorphisms of pollen and stigmas. The topographical complementarity hypothesis proposes that ancillary polymorphisms function in the rejection of incompatible pollen thus promoting disassortative pollination. Here, we test this hypothesis by investigating patterns of pollen transfer and capture in populations of dimorphic Armeria maritima and A. pubigera and distylous Limonium vulgare (Plumbaginaceae), and by studying pollen adherence and germination patterns in A. maritima following controlled hand-pollinations. Armeria lacks reciprocal herkogamy allowing the evaluation of the extent to which ancillary polymorphisms affect the composition of pollen loads. We compared the amounts of compatible and incompatible pollen on stigmas in natural populations and calculated the proficiencies of pollen transfer for each mating type. We detected disassortative pollination in each species, and mating types did not differ in compatible pollen capture, although cob stigmas captured more incompatible pollen. Controlled hand-pollinations revealed the failure of incompatible pollen to adhere and germinate on stigmas. Our results provided evidence that, while structural in nature, pollen-stigma dimorphisms are tightly associated with heteromorphic incompatibility and likely function to promote disassortative pollination in the absence of reciprocal herkogamy.

绝大多数异型花柱植物（heterostylous plants）均具备柱头与花药的互交排列模式（即异型雌雄异位，reciprocal herkogamy）、异型自交不亲和（heteromorphic self-incompatibility）以及花粉与柱头的附属多态性（ancillary polymorphisms）。地形互补假说（topographical complementarity hypothesis）提出，附属多态性可通过排斥不亲和花粉，进而促进异配传粉（disassortative pollination）。本研究通过以下两种方式验证该假说：一是探究二型性海石竹（Armeria maritima）、毛花海石竹（A. pubigera）以及二型花柱普通补血草（Limonium vulgare，白花丹科Plumbaginaceae）种群内的花粉传递与捕获模式；二是在控制性人工授粉（controlled hand-pollinations）后，研究海石竹的花粉附着与萌发模式。海石竹属植物不具备异型雌雄异位结构，这为评估附属多态性对花粉负载组成的影响程度提供了可行条件。我们对自然种群中柱头上的亲和与不亲和花粉数量进行了比较，并计算了每种交配类型的花粉传递效率。我们在所有受试物种中均检测到异配传粉现象；尽管cob型柱头捕获的不亲和花粉更多，但不同交配类型的亲和花粉捕获量并无显著差异。控制性人工授粉实验显示，不亲和花粉无法在柱头上附着并萌发。本研究结果证实，尽管花粉-柱头二态性本质上属于结构性状，但其与异型自交不亲和紧密关联，且在缺乏异型雌雄异位的情况下，同样可能发挥促进异配传粉的作用。