被子植物退化雄蕊的功能类型及其意义

The Classification and Functional Significance of Staminodes in Angiosperms

退化雄蕊是指没有花药或花药不可育的雄蕊,发现于被子植物32.5%的科以及54.4%的属中,它们在形态和生化组成上都与可育雄蕊有着显著区别。虽然丢失了产生可育花粉的能力、无法发挥雄性繁殖功能,某些退化雄蕊在进化过程中重新获得了一些有助于植物繁殖成功的新功能。本文将这些具有功能的退化雄蕊细分为8类:(1)信号型;(2)报酬型;(3)欺骗传粉型;(4)辅助传粉昆虫在花内活动;(5)辅助授粉;(6)协助花粉二次呈现;(7)保护其他花结构;(8)避免自交。退化雄蕊作为花结构的一部分,其功能集中于促进植物的繁殖成功,主要通过与传粉昆虫的相互作用来提高传粉效率。此外,某些植物的退化雄蕊也可能同时具有多种功能,并且其功能的强弱与传粉者的种类、行为、大小和频率相关。正确评估退化雄蕊对植物繁殖成功的影响,需要多学科手段来系统的研究,以便能更加深入的理解不同近缘关系的物种间退化雄蕊功能的差异,揭示退化雄蕊在被子植物系统进化中的意义。

All staminodes in an androecium fail to produce viable pollen grains and cannot contribute directly to male fitness. Staminodes are identified in the flowers of approximately 54% of known genera representing 〉 32% of all angiosperm families. The functional morphology and biochemistry of staminodes differs significantly from stamens with fertile anthers. In the absence of sperm production, some staminodes evolved novel adaptations contributing to the reproductive success of their flowers. We subdivided these staminodes into eight functional types ： 1 ） Staminodes offering visual/olfactory cues ; 2） Staminodes offering edible/inedible rewards ; 3 ） Staminodes that deceive pollina- tors with false rewards ; 4） Staminodes facilitating or directing the movements of pollinators in flowers ; 5 ） Stami- nodes that facilitate stigma movement; 6） Staminodes functioning as secondary pollen presenters; 7） Staminodes that protect other floral organs; 8） Staminodes that prevent mechanical self-pollination （autogamy）. As a component within a flower, the majority of staminodes function as promoters of reproductive success by interacting directly with the pollinator to increase pollination efficiency （both pollen dispersal and deposition）. Therefore, it is not surprisingthat one staminode may have more than one function over the flower＇s lifespan and is closely associated with the size, abundance, behavior and taxonomic diversity of pollinators, floral predators and thieves. To correctly evaluate the function of staminodes, multi-disciplinary approach using a range of protocols, equipment and materials is suggested. This approach allows us to compare the roles different staminodes play in the reproductive success of both closely and distantly related angiosperms, then uncover their evolutionary significance in angiosperm diversification.