Yong Ming-Li, Fan Lin-Lin, Li Dan-Yang, Liu Yi-Jia, Cheng Fang-Min, Xu Ying, Wang Zheng-Yi, Hu Dong-Wei
The State Kay Laboratory for Rice Biology, Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
Microsc Res Tech. 2016 Sep;79(9):838-44. doi: 10.1002/jemt.22710. Epub 2016 Jun 30.
Rice false smut, caused by the fungal pathogen Villosiclava virens, is one of the most important rice diseases in the world. Previous studies reported that the pathogen has less number of cell wall-degraded genes and attacks dominantly rice stamen filaments and extends intercellularly. To reveal why the fungus infects plant stamen filaments, inoculation test on barley was carried out with the similar protocol to rice. The experimental results showed that the fungus could penetrate quickly into barley stamen filaments and extends both intracellularly and intercellularly, usually resulting in severe damage of the stamen filament tissues. It also attacked young barley lodicules and grew intercellularly by chance. The light microscopic observations found that the epidermal and cortex cells in barley stamen filaments arranged loosely with very thick cell walls and large cell gaps. Cellulose microfibrils in barley stamen filament cell walls arranged very sparsely so that the cell walls looked like transparent. The cell walls were very soft and flexible, and often folded. However, V. virens extended dominantly in the noncellulose regions and seemed never to degrade microfibrils in barley and rice cell walls. This suggested that the unique structures of rice and barley stamen filaments should be fit for their function of elongation in anthesis, and also endow with the susceptibility to the fungus, V. virens.
稻曲病由真菌病原菌稻绿核菌引起，是世界上最重要的水稻病害之一。先前的研究报道，该病原菌细胞壁降解基因数量较少，主要侵染水稻雄蕊花丝并在细胞间扩展。为揭示该真菌为何侵染植物雄蕊花丝，采用与水稻相似的方案对大麦进行了接种试验。实验结果表明，该真菌能迅速侵入大麦雄蕊花丝，并在细胞内和细胞间扩展，通常会导致雄蕊花丝组织严重受损。它还偶尔侵染大麦幼颖，并在细胞间生长。光学显微镜观察发现，大麦雄蕊花丝的表皮细胞和皮层细胞排列疏松，细胞壁非常厚，细胞间隙大。大麦雄蕊花丝细胞壁中的纤维素微纤丝排列非常稀疏，以至于细胞壁看起来像透明的。细胞壁非常柔软且有弹性，经常折叠。然而，稻绿核菌主要在非纤维素区域扩展，似乎从未降解大麦和水稻细胞壁中的微纤丝。这表明水稻和大麦雄蕊花丝的独特结构应适合其在开花期伸长的功能，同时也使其对稻绿核菌具有易感性。
