Gan Xiaohong, Cao Lingling, Zhang Xia, Li Huaichun
College of Life Science, China West Normal University, Nanchong, 637009, PR., China.
Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong, 637009, PR., China.
Bot Stud. 2013 Dec;54(1):50. doi: 10.1186/1999-3110-54-50. Epub 2013 Oct 29.
Tetracentron sinense Oliv. is an endangered tree mainly distributed in south-central China. The breeding system and pollination ecology of T. sinense are unclear. With a conservation perspective, the floral biology, breeding system and pollination ecology of Tetracentron sinense Oliv. were investigated, in order to discuss the endangered factors related to pollination, and to provide important information for its conservation.
Our results revealed four important aspects of the reproductive biology of T. sinense. 1) T. sinense usually flowers by the beginning of June, and the flowering period of the population is about two months, and the florescence of florets lasted for 15 to 24 days with delicate fragrance. 2) The pollen/ovule ratio is 720 ± 28, and the outcrossing index is three. Artificial pollination experiments showed that T. sinense is self-compatible, with facultative xenogamy and no indication of agamospermy. 3) The pollination syndrome is ambophily, and self-pollination plays an important role in fruit production if wind and insect pollination is unavailable. 4) Insect pollinators were predominantly represented by Coleoptera, Diptera and Hymenoptera. Syrphid fly and bees were the main effective pollinators.
The results suggested that T. sinense exhibits a mixed-mating system, and autogamy in its breeding system may provide reproductive assurance for the population maintenance. During flowering and pollination in natural population, the decrease of population density and harsh environmental condition might be one of crucial reasons resulting in endanger for this species.
水青树是一种濒危树种，主要分布于中国中南部。水青树的繁育系统和传粉生态学尚不清楚。从保护的角度出发，对水青树的花生物学、繁育系统和传粉生态学进行了研究，以探讨与传粉相关的濒危因素，并为其保护提供重要信息。
我们的研究结果揭示了水青树生殖生物学的四个重要方面。1）水青树通常在6月初开花，种群花期约两个月，小花花期持续15至24天，花香淡雅。2）花粉/胚珠比为720±28，杂交指数为3。人工授粉实验表明，水青树自交亲和，兼性异交，无无融合生殖迹象。3）传粉综合征为兼性传粉，如果风媒和虫媒传粉不可用，自花传粉在果实形成中起重要作用。4）传粉昆虫主要有鞘翅目、双翅目和膜翅目。食蚜蝇和蜜蜂是主要的有效传粉者。
结果表明，水青树表现出混合交配系统，其繁育系统中的自花授粉可能为种群维持提供繁殖保障。在自然种群开花和传粉期间，种群密度的降低和恶劣的环境条件可能是导致该物种濒危的关键原因之一。
