Chaudhary Anjali, Yadav S R, Tandon Rajesh
Department of Botany, University of Delhi, 110007, New Delhi, Delhi, India.
Department of Botany, Shivaji University, 416004, Kolhapur, Maharashtra, India.
J Plant Res. 2018 Jul;131(4):599-610. doi: 10.1007/s10265-018-1016-y. Epub 2018 Feb 19.
Numerous bladderwort (Utricularia) species are distributed worldwide, but their reproductive biology is rarely investigated. Bladderworts are known to depend on tiny organisms to meet a significant proportion of their energy requirement by trapping them in bladders. However, information on the extent of their reliance on insects for pollination success is limited. We examined the reproductive strategy of two Utricularia species viz. Utricularia praeterita and U. babui, endemic to Western Ghats, India. The main aspects of the investigation involved floral biology, breeding system, pollination mechanism, and reproductive success. Flowers of both the species are structured for outbreeding through entomophilous floral suites, herkogamy, protandrous dichogamy and sensitive lobes of the stigma. With nearly 65% natural fruit-set, both the species appeared to be sufficiently open-pollinated. However, pollinators failed to show in plants of U. praeterita while in U. babui there was an apparent mismatch between the extent of fruit-set and pollinator visits. The study demonstrated that in the absence/insufficient visits of pollinators, the two species resort to autonomous selfing. In U. babui, denser patches of plants appeared to be crucial for attracting the pollinators. Both species are self-compatible, and reproductive success is predominantly achieved by delayed autonomous selfing. The sensitive stigma in the species fails to prevent selfing due to diminished herkogamy during the late anthetic stages. It is inferred that in the pollinator-limited environment, delayed selfing contributes to absolute natural fecundity in U. praeterita, while it produces a mixed progeny in U. babui.
许多狸藻属（狸藻）物种分布于全球，但对其繁殖生物学的研究却很少。众所周知，狸藻通过将微小生物捕获在囊中来满足其很大一部分能量需求。然而，关于它们在授粉成功方面对昆虫的依赖程度的信息有限。我们研究了两种狸藻的繁殖策略，即印度西高止山脉特有的前狸藻和巴布狸藻。研究的主要方面包括花生物学、繁育系统、授粉机制和繁殖成功率。这两个物种的花都通过虫媒花系列、雌雄异位、雄蕊先熟的雌雄异熟和柱头的敏感裂片来进行异花授粉。两种物种的自然坐果率都接近65%，似乎都能充分进行开放授粉。然而，在前狸藻的植株上没有传粉者出现，而在巴布狸藻中，坐果率和传粉者访花次数之间明显不匹配。研究表明，在传粉者缺失/访花不足的情况下，这两个物种会采取自动自花授粉。在巴布狸藻中，较密集的植株斑块似乎对吸引传粉者至关重要。这两个物种都是自交亲和的，繁殖成功主要通过延迟自动自花授粉来实现。由于在开花后期雌雄异位减少，该物种中敏感的柱头无法阻止自花授粉。据推测，在传粉者受限的环境中，延迟自花授粉有助于前狸藻实现绝对自然繁殖力，而在巴布狸藻中则产生混合后代。
