Cordia subcordata (Boraginaceae), a distylous species on oceanic coral islands, is self-compatible and pollinated by a passerine bird
Cordia subcordata (Boraginaceae), a distylous species on oceanic coral islands, is self-compatible and pollinated by a passerine bird
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DOI：
10.5091/plecevo.2020.1757
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发表时间：
2020-11
影响因子：
1.1
通讯作者：
Xiangping Wang;Meihong Wen;Ming-Jou Wu;Dianxiang Zhang
中科院分区：
文献类型：
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作者：
Xiangping Wang;Meihong Wen;Ming-Jou Wu;Dianxiang Zhang
背景和目的-二苯乙烯通常在海洋岛屿上很罕见，这可能是由于二苯乙烯植物难以在这些岛屿上定居。为了研究科迪亚（Cordia subcordata）的生殖系统特征，并了解这种二花丛物种如何在这些岛屿上维持自身，我们对其生殖和授粉生物学进行了研究。方法：在控制形态间、形态内和自花授粉的情况下，研究了该物种的自交不亲和性。通过对单次访花后柱头上的花粉粒数进行统计，探讨不同访花者的授粉效率。主要结果-我们的研究表明，Cordia subcordata显示出互惠雌雄同体，这是典型的二花科物种。在授粉处理下，花粉管均能到达花柱基部并进入胚珠内。四次人工授粉实验的结果表明，两种花型间的结实率没有差异，这表明亚Cordia亚cordata缺乏异花柱自交不亲和。研究发现，访花频率最高的两种昆虫——日本带蓟（Zosterops japonicus）和中国蜜蜂（Apis cerana）分别采集大量花蜜和花粉粒，其中日本带蓟（Zosterops japonicus）是最有效的传粉者，在访花过程中会在柱头上留下大量花粉粒。结论-我们的研究结果表明，Cordia subcordata通过自交和海洋岛屿上最常见的雀形目鸟类的授粉相结合而产生果实，从而在群岛中建立并持续存在。
Background and aims – Distyly is usually rare on oceanic islands, which is probably due to the difficulty for distylous plants to colonize those islands. However, Cordia subcordata was observed to be distylous with shortand long-styled morphs on the Xisha Islands in the South China Sea. To characterize the reproduction system of Cordia subcordata and to understand how this distylous species maintains itself on these islands, we studied its reproductive and pollination biology. Methods – Seed set and pollen tube growth under manipulated intermorph, intramorph, and self-pollination were examined to investigate self-incompatibility in the species. The number of pollen grains deposited on the stigmas after a single pollinator visit were counted to investigate the pollination efficiency of different visitors. Key results – Our study indicated that Cordia subcordata shows reciprocal herkogamy as is typical in distylous species. Pollen tubes could reach the base of the style and move into the ovules under all the manipulated pollination treatments in both morphs. Seed set resulting from four hand-pollination experiments did not show any differences between both morphs, suggesting that Cordia subcordata lacks heterostylous self-incompatibility. The most frequent flower visitors, Zosterops japonicus and Apis cerana, were observed foraging on the large volumes of nectar and pollen grains, respectively, with Zosterops japonicus being the most effective pollinator, depositing large number of pollen grains on the stigmas during their visits. Conclusions – Our findings show that Cordia subcordata established itself and persists in the archipelago by producing fruits through a combination of self-compatibility and pollination by the most common passerine bird on the oceanic islands.