Mesquita-Neto J N, Costa B K P, Schlindwein C
Departamento de Botânica, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Plant Biol (Stuttg). 2017 Nov;19(6):942-950. doi: 10.1111/plb.12609. Epub 2017 Aug 28.
Heteranthery, the presence of feeding and pollinating anthers in the same flower, seems to mediate the evolutionary dilemma for plants to protect their gametes and yet provide food for pollinators. This study aims to elucidate the role of heteranthery in the buzz-pollinated Senna reniformis. The fecundity of pollen from long-, medium- and short-sized anthers was determined by hand cross-pollination experiments, and the quantity, size, ornamentation and viability of pollen of different anthers were compared. Rates of flower rejection by bees were measured in anther removal experiments to assess the preferences of flower visitors for feeding or pollinating anthers. Large bees, which were the effective pollinators of self-incompatible S. reniformis, avoided flowers without short feeding anthers, but not those without medium or long anthers. Illegitimate small and medium-sized bees were unresponsive to anther exclusion experiments. Long anthers deposited pollen on the back and short anthers on the venter of large bees. Pollen from long anthers had higher in vitro viability and higher fruit and seed set after cross-pollination than pollen from other sized anthers. Short anthers produce feeding pollen to effective pollinators and long anthers are related to pollination of S. reniformis. Bee behaviour and size was found to directly influence the role of anthers in the 'division of labour'. Only large bee pollinators that carry the pollinating pollen from long anthers in 'safe sites' associated short anthers with the presence of food. In the absence of these larger bee pollinators, the role of heteranthery in S. reniformis would be strongly compromised and its function would be lost.
异型雄蕊，即同一朵花中存在供取食的花药和传粉的花药，似乎解决了植物在保护其配子的同时为传粉者提供食物这一进化困境。本研究旨在阐明异型雄蕊在蜂鸣传粉的肾叶决明中的作用。通过人工异花授粉实验确定了长、中、短花药花粉的繁殖力，并比较了不同花药花粉的数量、大小、纹饰和活力。在去除花药的实验中测量了蜜蜂拒绝花朵的比率，以评估访花者对供取食花药或传粉花药的偏好。大型蜜蜂是自交不亲和的肾叶决明的有效传粉者，它们避开没有短供食花药的花朵，但不避开没有中花药或长花药的花朵。非法的中小型蜜蜂对花药去除实验没有反应。长花药将花粉沉积在大型蜜蜂的背部，短花药则沉积在其腹部。与其他大小花药的花粉相比，长花药的花粉在体外具有更高的活力，异花授粉后具有更高的坐果率和种子结实率。短花药为有效传粉者产生供取食的花粉，长花药与肾叶决明的传粉有关。研究发现，蜜蜂的行为和大小直接影响花药在“分工”中的作用。只有大型传粉蜜蜂在“安全部位”携带长花药的传粉花粉时，才会将短花药与食物的存在联系起来。在没有这些大型传粉蜜蜂的情况下，异型雄蕊在肾叶决明中的作用将受到严重损害，其功能也将丧失。
