Xue Yang, Hu Ming, Chen Shanshan, Hu Anqun, Li Shimao, Han Haiya, Lu Guangtao, Zeng Lisha, Zhou Jianuan
Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, China.
Agricultural Technology Service Centre of Daojiao Town, Dongguan 523170, China.
Plant Dis. 2021 Aug;105(8):2078-2088. doi: 10.1094/PDIS-10-20-2292-RE. Epub 2021 Sep 15.
Rice bacterial blight is a devastating bacterial disease threatening rice yield all over the world and pv. is traditionally believed to be the pathogen. In recent years, we have received diseased rice samples with symptoms of blighted leaves from Sichuan and Guangdong provinces, China. Pathogen isolation and classification identified two different enterobacteria as the causal agents, namely and . Among them, was isolated from samples of both provinces, and was only isolated from the Sichuan samples. Different from rice foot rot pathogen EC1 and rice bacterial blight pathogen pv. PXO99A, strains SC1, RG1, and SC7 produced rare cell wall degrading enzymes (CWDEs) but more extrapolysaccharides (EPS). strains SC1 and RG1 produced bacteriostatic substances while strain SC7 produced none. Pathogenicity tests indicated that all of them infected monocotyledonous rice and banana seedlings, but not dicotyledonous potato, radish, or cabbage. Moreover, strain RG1 was most virulent, while strains SC1 and SC7 were similarly virulent on rice leaves, even though strain SC1 propagated significantly faster in rice leaf tissues than strain SC7. This study firstly discovered as a new pathogen of rice bacterial blight, and in some cases, could be a companion pathogen. Analysis on production of virulence factors suggested that both pathogens probably employ a different mechanism to infect hosts other than using cell wall degrading enzymes to break through host cell walls.
水稻白叶枯病是一种毁灭性的细菌性病害，威胁着全球水稻产量，传统上认为稻黄单胞菌水稻致病变种（Xanthomonas oryzae pv. oryzae）是病原体。近年来，我们收到了来自中国四川省和广东省的有叶片枯萎症状的患病水稻样本。病原菌的分离和分类确定了两种不同的肠杆菌为致病因子，即SC1和RG1。其中，SC1在两个省份的样本中均有分离，而RG1仅从四川样本中分离得到。与水稻基腐病病原菌EC1和水稻白叶枯病病原菌稻黄单胞菌水稻致病变种PXO99A不同，SC1、RG1和SC7菌株产生的细胞壁降解酶（CWDEs）很少，但胞外多糖（EPS）较多。SC1和RG1菌株产生抑菌物质，而SC7菌株不产生。致病性测试表明，它们都能感染单子叶水稻和香蕉幼苗，但不能感染双子叶的马铃薯、萝卜或卷心菜。此外，RG1菌株的毒性最强，而SC1和SC7菌株在水稻叶片上的毒性相似，尽管SC1菌株在水稻叶片组织中的繁殖速度明显快于SC7菌株。本研究首次发现RG1是水稻白叶枯病的一种新病原体，在某些情况下，SC1可能是伴生病原体。对毒力因子产生的分析表明，这两种病原体可能采用不同的机制感染宿主，而不是利用细胞壁降解酶突破宿主细胞壁。
