不同发育阶段的黄癣蜂巢珊瑚共生虫黄藻多样性

Diversity of Symbiodinium associated with Favia favus at different life stages

摘要:

【背景】黄癣蜂巢珊瑚是我国南海主要的造礁石珊瑚之一，但至今未见对其共生虫黄藻的相关研究报道。【目的】研究黄癣蜂巢珊瑚不同发育阶段的共生虫黄藻多样性，探讨其获取途径。【方法】用荧光显微镜观察黄癣蜂巢珊瑚卵子、浮浪幼虫以及珊瑚成体中的共生虫黄藻。基于ITS2序列的克隆文库技术分析珊瑚卵子、浮浪幼虫、成体中共生虫黄藻的多样性。【结果】荧光显微镜观察结果显示，黄癣蜂巢卵子及发育至第4天的浮浪幼虫中均无共生虫黄藻。没有在黄癣蜂巢珊瑚卵子及4 d浮浪幼虫中检测到虫黄藻ITS2序列，但是在黄癣蜂巢珊瑚成体中检测到共生虫黄藻序列，系统发育分析提示为C1型虫黄藻。【结论】成体黄癣蜂巢珊瑚中发现了共生虫黄藻，而卵子、浮浪幼虫阶段均未发现虫黄藻，提示黄癣蜂巢珊瑚中的虫黄藻可能是后期从海水中水平转移而来，而不是由母体垂直遗传的。

Abstract:

[Background] Favia favus is one of the main reef-building corals in the South China Sea, To our knowledge, to date no study has been performed on the symbiotic zooxanthellae in F. favus. [Objective] To investigate the phylogenetic diversity of the Symbiodinium in F. favus at different life stages, and to gain insights into potential acquisition mode of the Symbiodinium. [Methods] Fluorescence microscopy was used to detect the presence of symbiotic zooxanthellae in the eggs, larvae and adults of F. favus, respectively. Meanwhile, the clone library based on ITS2 sequence was constructed to assess the diversity of Symbiodinium. [Results] By means of direct examination with fluorescence microscopy, zooxanthellae was absent in the eggs and larvae but present in the adults of F. favus, which was assigned to Symbiodinium type C1 based on the ITS2 sequence analysis. [Conclusion] Only Symbiodinium type C1 was present in adults rather than eggs and larvae, suggesting that the symbiotic zooxanthellae in F. favus were probably acquired by horizontal transmission from the environment instead of vertical transmission.