Leaf-derived cecidomyiid galls are sinks in Machilus thunbergii (Lauraceae) leaves
Leaf-derived cecidomyiid galls are sinks in Machilus thunbergii (Lauraceae) leaves
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DOI：
10.1111/ppl.12186
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发表时间：
2014-11-01
影响因子：
6.4
通讯作者：
Yang, Chi-Ming
中科院分区：
文献类型：
--
作者：
Huang, Meng-Yuan;Huang, Wen-Dar;Yang, Chi-Ming
在探讨虫瘿与寄主植物的源库关系时，营养假说、环境假说和天敌假说一直存在争议。本研究采用叶绿素荧光、气体交换量、气孔导度、总碳、总氮、总可溶性糖、总淀粉以及扫描电镜和透射电镜等技术对两种虫瘿的源库关系进行了研究。与寄主叶片相比，这些虫瘿表现出略低的叶绿素荧光，但气体交换能力和气孔导度没有检测到。扫描电镜观察表明，寄主叶片下表皮含有正常数量的气孔，而两种虫瘿的内外表面均未观察到气孔。此外，虫瘿内表面覆盖有多种真菌菌丝。虫瘿中总碳、氮含量较低，但C/N比高于寄主叶片。这两种类型的虫瘿积累较高的总可溶性糖和淀粉比寄主叶片。透射电子显微镜还显示，这两种类型的虫瘿含有plastelluli和巨大的淀粉粒在虫瘿发展。结果表明，叶源瘿蚊在润楠叶中是一个汇。然而，它是令人困惑的幼虫如何循环和平衡CO2和O-2在无气孔的虫瘿生长室。
Three relevant hypotheses-nutrition, environment and the enemies hypothesis-often invoked to explore source and sink relationships between galls and their host plants are still under dispute. In this research, chlorophyll fluorescence, gas exchange capacity, stomatal conductance, total carbon and nitrogen, total soluble sugars and starches, and scanning and transmission electron microscopy of two types of galls were used to investigate source-sink relationships. Compared with host leaves, these galls demonstrated slightly lower chlorophyll fluorescence; however, gas exchange capacity and stomatal conductance were not detected at all. Scanning electron micrographs demonstrated that the abaxial epidermis of host leaves contain normal amounts of stomata, whereas no stomata were observed on the exterior and interior surfaces of both types of galls. In addition, gall inner surfaces were covered with many kinds of fungal hyphae. Gall total carbon (C) and nitrogen (N) levels were lower but the C/N ratio was higher in galls than host leaves. Both types of galls accumulated higher total soluble sugars and starches than host leaves. Transmission electron micrographs also revealed that both types of galls contain plastoglobuli and giant starch granules during gall development. Results strongly indicate that leaf-derived cecidomyiid galls are sinks in Machilus thunbergii leaves. However, it is perplexing how larvae cycle and balance CO2 and O-2 in gall growth chambers without stomata.