About one-fifth of angiosperms reproduce predominantly through self-fertilization, mediated by morphological and functional flower traits. Autonomous selfing is rare in Melastomataceae, a megadiverse family with most species featuring poricidal anthers and herkogamy. However, previous studies suggested that some Bertolonia spp. were capable of autonomous selfing. Here, we investigated the existence of autonomous selfing in the group and, considering its specialized floral morphology, the mechanisms involved in this process. We conducted studies on floral biology, pollination experiments and pollinator visitation rates for Bertolonia paranaensis (anthers with introrse pores) and Bertolonia mosenii (anthers with extrorse pores). The transient absence of herkogamy and the dynamics of the movements of the flower parts during post-anthesis events promoted delayed selfing in both species. In post-anthesis flowers, pollen grains germinate inside the anthers, the pollen tubes come out through the anther pores and then reach the stigma, penetrating the transmission tissue, and fertilize the ovules. Both species received visits from buzzing bees and have a mixed mating system, i.e. the capacity of cross-pollination and delayed selfing-pollination. We present the first description of an autonomous selfing mechanism for plants with poricidal anthers, for which we coin the name “pollen tube shower”. Pollen tube shower promotes reproductive assurance to flowers that have not been pollinated and ensures reproductive success of individuals in the absence of pollinators.

中文翻译：

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Bertolonia (Melastomataceae) 中的“花粉管淋浴”：一种新的延迟自交机制在具有杀虫花药的花朵中

大约五分之一的被子植物主要通过自我受精繁殖，由花的形态和功能性状介导。自主自交在 Melastomataceae 中是罕见的，这是一个具有大多数物种以杀虫花药和 herkogamy 为特征的大型多样性家族。然而，先前的研究表明，一些 Bertolonia spp。能够自主自交。在这里，我们研究了该群体中自主自交的存在，并考虑到其特殊的花形态，研究了这一过程所涉及的机制。我们对 Bertolonia paranaensis（具有内孔的花药）和 Bertolonia mosenii（具有外孔的花药）的花卉生物学、授粉实验和传粉者访问率进行了研究。在开花后事件期间，雌雄同体的短暂缺失和花部分运动的动态促进了这两个物种的延迟自交。在花后花中，花粉粒在花药内萌发，花粉管从花药孔中出来，到达柱头，穿透传播组织，使胚珠受精。这两个物种都接受了嗡嗡的蜜蜂的访问，并具有混合交配系统，即异花授粉和延迟自花授粉的能力。我们首次描述了具有杀虫花药的植物的自主自交机制，为此我们将其命名为“花粉管淋浴”。花粉管淋浴促进了未授粉的花朵的繁殖保证，并确保在没有授粉者的情况下个体的繁殖成功。