Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, P.R. China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi, P.R. China.
Tree Physiol. 2017 Jan 31;37(1):82-97. doi: 10.1093/treephys/tpw097.
Avicennia marina (Forsk.) Vierh is a widespread mangrove species along the southeast coasts of China. Recently, the outbreak of herbivorous insect, Phyllocnistis citrella Stainton, a leaf miner, have impacted on the growth of A. marina. Little is reported about the responses of A. marina to leaf miner infection at the biochemical, physiological and molecular levels. Here, we reported the responses of A. marina to leaf miner infection from the aspects of leaf structure, photosynthesis, and antioxidant system and miner responsive genes expression. A. marina leaves attacked by the leaf miner exhibited significant decreases in chlorophyll, carbon and nitrogen contents, as well as a decreased photosynthetic rate. Scanning and transmission electron microscopic observations revealed that the leaf miner only invaded the upper epidermis and destroyed the epidermal cell, which lead to the exposure of salt glands. In addition, the chloroplasts of mined leaves (ML) were swollen and the thylakoids degraded. The maximal net photosynthetic rate, stomatal conductance (Gs), carboxylation efficiency (CE), dark respiration (Rd), light respiration (Rp) and quantum yields (AQE) significantly decreased in the ML, whereas the light saturation point (Lsp), light compensation point (Lcp), water loss and CO2 compensation point (Г) increased in the ML. Moreover, chlorophyll fluorescence features also had been changed by leaf miner attacks. Interestingly, higher generation rate of O2ˉ· and lower antioxidant enzyme expression in the mined portion (MP) were found; on the contrary, higher H2O2 level and higher antioxidant enzyme expression in the non-mined portion (NMP) were revealed, implying that the NMP may be able to sense that the leaf miner attacks had happened in the MP of the A. marina leaf via H2O2 signaling. Besides, the protein expression of glutathione S-transferase (GST) and the glutathione (GSH) content were increased in the ML. In addition, insect resistance-related gene expression such as chitinase 3, RAR1, topless and PIF3 had significantly increased in the ML. Taken together, our data suggest that leaf miners could significantly affect leaf structure, photosynthesis, the antioxidant system and miner responsive gene expression in A. marina leaves.
海桑（Forsk.）Vierh 是中国东南沿海广泛分布的红树林物种。最近，食叶昆虫榕透翅毒蛾（Phyllocnistis citrella Stainton）的爆发对海桑的生长产生了影响。然而，关于海桑对叶虫感染的生化、生理和分子水平的反应，报道甚少。在这里，我们从叶片结构、光合作用和抗氧化系统以及虫蛀响应基因表达等方面报道了海桑对叶虫感染的反应。受叶虫侵害的海桑叶片表现出叶绿素、碳和氮含量显著下降，以及光合速率降低。扫描和透射电子显微镜观察表明，叶虫仅侵入上表皮并破坏表皮细胞，导致盐腺暴露。此外，受虫蛀叶片（ML）的叶绿体肿胀，类囊体降解。最大净光合速率、气孔导度（Gs）、羧化效率（CE）、暗呼吸（Rd）、光呼吸（Rp）和量子产率（AQE）在 ML 中显著降低，而 ML 中的光饱和点（Lsp）、光补偿点（Lcp）、水分损失和 CO2补偿点（Г）增加。此外，叶虫攻击还改变了叶绿素荧光特性。有趣的是，在受虫蛀部分（MP）中发现了更高的 O2ˉ·产生速率和更低的抗氧化酶表达；相反，在未受虫蛀部分（NMP）中发现了更高的 H2O2 水平和更高的抗氧化酶表达，这表明 NMP 可能能够通过 H2O2 信号感知到叶虫在海桑叶片的 MP 中发生了攻击。此外，谷胱甘肽 S-转移酶（GST）的蛋白表达和谷胱甘肽（GSH）含量在 ML 中增加。此外，在 ML 中，几丁质酶 3、RAR1、无顶和 PIF3 等昆虫抗性相关基因的表达显著增加。综上所述，我们的数据表明，叶虫可显著影响海桑叶片的叶片结构、光合作用、抗氧化系统和虫蛀响应基因表达。
