Institute of Crop Sciences, National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Laboratory of Integrated and Urban Phytopathology, Gembloux Agro-Bio Tech-University of Liège, Passage des déportés, 2, 5030 Gembloux, Belgium.
Int J Mol Sci. 2018 Apr 13;19(4):1187. doi: 10.3390/ijms19041187.
Wheat ( L.) production is essential for global food security. Infection of barley yellow dwarf virus-GAV (BYDV-GAV) results in wheat showing leaf yellowing and plant dwarfism symptom. To explore the molecular and ultrastructural mechanisms underlying yellow dwarf symptom formation in BYDV-GAV-infected wheat, we investigated the chloroplast ultrastructure via transmission electron microscopy (TEM), examined the contents of the virus, H₂O₂, and chlorophyll in Zhong8601, and studied the comparative transcriptome through microarray analyses in the susceptible wheat line Zhong8601 after virus infection. TEM images indicated that chloroplasts in BYDV-GAV-infected Zhong8601 leaf cells were fragmentized. Where thylakoids were not well developed, starch granules and plastoglobules were rare. Compared with mock-inoculated Zhong8601, chlorophyll content was markedly reduced, but the virus and H₂O₂ contents were significantly higher in BYDV-GAV-infected Zhong8601. The transcriptomic analyses revealed that chlorophyll biosynthesis and chloroplast related transcripts, encoding chlorophyll a/b binding protein, glucose-6-phosphate/phosphate translocator 2, and glutamyl-tRNA reductase 1, were down-regulated in BYDV-GAV-infected Zhong8601. Some phytohormone signaling-related transcripts, including abscisic acid (ABA) signaling factors (phospholipase D alpha 1 and calcineurin B-like protein 9) and nine ethylene response factors, were up-regulated. Additionally, reactive oxygen species (ROS)-related genes were transcriptionally regulated in BYDV-GAV infected Zhong8601, including three up-regulated transcripts encoding germin-like proteins (promoting ROS accumulation) and four down-regulated transcripts encoding peroxides (scavenging ROS). These results clearly suggest that the yellow dwarf symptom formation is mainly attributed to reduced chlorophyll content and fragmentized chloroplasts caused by down-regulation of the chlorophyll and chloroplast biosynthesis related genes, ROS excessive accumulation, and precisely transcriptional regulation of the above-mentioned ABA and ethylene signaling- and ROS-related genes in susceptible wheat infected by BYDV-GAV.
小麦（L.）的生产对全球粮食安全至关重要。感染大麦黄矮病毒-GAV（BYDV-GAV）会导致小麦出现叶片黄化和植株矮化症状。为了探索 BYDV-GAV 感染小麦产生黄矮症状的分子和超微结构机制，我们通过透射电子显微镜（TEM）观察叶绿体超微结构，检测感病小麦品种‘中 8601’中的病毒、H₂O₂和叶绿素含量，并通过 microarray 分析比较病毒感染前后‘中 8601’的转录组。TEM 图像显示，BYDV-GAV 感染的‘中 8601’叶片细胞中的叶绿体碎片化。类囊体发育不良，淀粉粒和质体小球稀少。与 mock 接种的‘中 8601’相比，BYDV-GAV 感染的‘中 8601’中叶绿素含量明显降低，但病毒和 H₂O₂含量显著升高。转录组分析显示，BYDV-GAV 感染的‘中 8601’中叶绿素生物合成和叶绿体相关转录本，如叶绿素 a/b 结合蛋白、葡萄糖-6-磷酸/磷酸转运蛋白 2 和谷氨酰-tRNA 还原酶 1 的表达下调。一些植物激素信号相关转录本，包括脱落酸（ABA）信号因子（磷脂酶 Dα1 和钙调神经磷酸酶 B 样蛋白 9）和 9 个乙烯响应因子，上调。此外，BYDV-GAV 感染的‘中 8601’中活性氧（ROS）相关基因转录被调控，包括 3 个上调的编码 germin-like 蛋白（促进 ROS 积累）的转录本和 4 个下调的编码过氧化物（清除 ROS）的转录本。这些结果清楚地表明，黄矮症状的形成主要归因于叶绿素含量降低和叶绿体碎片化，这是由叶绿素和叶绿体生物合成相关基因下调、ROS 过度积累以及易感小麦感染 BYDV-GAV 后 ABA 和乙烯信号转导和 ROS 相关基因的精确转录调控引起的。
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