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.

绝大多数花柱异长植物（heterostylous plants）均具备柱头与花药的交互排布模式（即交互雌雄异位，reciprocal herkogamy）、异形自交不亲和性（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）。本研究通过调查二型的（dimorphic）海石竹（Armeria maritima）、柔毛海石竹（A. pubigera）以及花柱二型的（distylous）普通补血草（Limonium vulgare，白花丹科Plumbaginaceae）种群的花粉传递与捕获格局，并开展人工控制授粉（controlled hand-pollinations）下海石竹的花粉附着与萌发模式研究，以此检验该假说。海石竹属（Armeria）不具备交互雌雄异位特性，这使得我们能够评估附属多态性对花粉负载组成的影响程度。研究人员对比了自然种群中柱头上的亲和与不亲和花粉数量，并计算了每种交配类型的花粉传递效率。本研究在所有供试物种中均检测到异配传粉现象，且不同交配类型的亲和花粉捕获量并无显著差异，尽管cob柱头捕获的不亲和花粉量更高。人工控制授粉实验结果显示，不亲和花粉无法在柱头上完成附着与萌发。本研究结果表明，尽管花粉-柱头二态性（pollen-stigma dimorphisms）本质上属于结构特征，但它与异形自交不亲和性紧密相关，且在缺乏交互雌雄异位的情况下，可能通过促进异配传粉发挥功能。