Liu Ning, Ning Guo-Ao, Liu Xiao-Hong, Feng Xiao-Xiao, Lu Jian-Ping, Mao Li-Juan, Su Zhen-Zhu, Wang Ying, Zhang Chu-Long, Lin Fu-Cheng
State Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.
College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.
Microbiol Res. 2016 Nov;192:326-335. doi: 10.1016/j.micres.2016.08.008. Epub 2016 Aug 12.
The endophytic fungus Harpophora oryzae is a beneficial endosymbiont isolated from wild rice. H. oryzae can not only promote rice growth and biomass accumulation but also protect rice roots from invasion by its close relative Magnaporthe oryzae. Autophagy is a highly evolutionary conserved process from lower to higher eukaryotic organisms, and is involved in the maintenance of normal cell differentiation and development. In this study, we isolated a gene (HoATG5) which encodes an essential protein required for autophagy from the beneficial endophyte fungus H. oryzae. Using targeted gene replacement, a ΔHoATG5 mutant was generated and used to investigate the biological functions of autophagy in H. oryzae. We found that the autophagic process was blocked in the HoATG5 deletion mutant. The mutant showed increased vegetative growth and sporulation, and was sensitive to nutrient starvation. The ΔHoATG5 mutant lost its ability to penetrate and infect the wounded barley leaves. These results provide new knowledge to elaborate the molecular machinery of autophagy in endophytic fungi.
内生真菌稻生哈茨木霉是从野生稻中分离出的一种有益内生共生菌。稻生哈茨木霉不仅能促进水稻生长和生物量积累，还能保护水稻根系免受其近亲稻瘟病菌的侵染。自噬是一个从低等真核生物到高等真核生物高度进化保守的过程，参与维持正常的细胞分化和发育。在本研究中，我们从有益内生真菌稻生哈茨木霉中分离出一个编码自噬所需必需蛋白的基因（HoATG5）。利用靶向基因置换技术，构建了ΔHoATG5突变体，并用于研究自噬在稻生哈茨木霉中的生物学功能。我们发现HoATG5缺失突变体中的自噬过程被阻断。该突变体营养生长和产孢增加，且对营养饥饿敏感。ΔHoATG5突变体失去了穿透和感染受伤大麦叶片的能力。这些结果为阐明内生真菌自噬的分子机制提供了新的知识。
