Pu Xiaoming, Xie Bingyan, Li Peiqian, Mao Zhenchuan, Ling Jian, Shen Huifang, Zhang Jingxin, Huang Ning, Lin Birun
College of Agriculture, Guangxi University, Nanning, China; Key Laboratory of New Technique for Plant Protection in Guangdong, Institute of Plant Protection, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
FEMS Microbiol Lett. 2014 Jun;355(2):142-51. doi: 10.1111/1574-6968.12461. Epub 2014 May 22.
A defence response can be induced by nonpathogenic Fusarium oxysporum CS-20 in several crops, but the molecular mechanism has not been clearly demonstrated. In the present study, we analysed the defence mechanism of a susceptible cucumber cultivar (Cucumis sativus L. 9930) against a pathogen (F. oxysporum f. sp. cucumerinum) through the root precolonization of CS-20. A challenge inoculation assay indicated that the disease severity index (DSI) was reduced, ranging from 18.83 to 61.67 in comparison with the pathogen control. Root colonization analysis indicated that CS-20 clearly did not appear to influence the growth of cucumber seedlings. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) revealed that CS-20-mediated defence response was activated by PR3, LOX1 and PAL1 and the pathogen-mediated resistance response was regulated by PR1 and PR3. Moreover, both nonpathogenic and pathogenic F. oxysporum were able to upregulate NPR1 expression. In contrast to a pathogen, CS-20 can activate the Ca(2+) /CaM signal transduction pathway, and the gene expression of both CsCam7 and CsCam12 increased significantly. The gene expression analysis indicated that CS-20 strongly enhanced the expression of PR3, LOX1, PAL1, NPR1, CsCam7 and CsCam12 after inoculation. Overall, the defence response induced by CS-20 can be controlled by multiple genes in the cucumber plant.
非致病性尖孢镰刀菌CS-20可在几种作物中诱导防御反应，但其分子机制尚未得到明确证实。在本研究中，我们通过CS-20的根部预定殖，分析了易感黄瓜品种（黄瓜9930）对病原菌（尖孢镰刀菌黄瓜专化型）的防御机制。挑战接种试验表明，病害严重指数（DSI）降低，与病原菌对照相比，范围为18.83至61.67。根部定殖分析表明，CS-20显然不会影响黄瓜幼苗的生长。定量逆转录聚合酶链反应（qRT-PCR）显示，CS-20介导的防御反应由PR3、LOX1和PAL1激活，病原菌介导的抗性反应由PR1和PR3调节。此外，非致病性和致病性尖孢镰刀菌均能上调NPR1的表达。与病原菌不同，CS-20可激活Ca(2+)/CaM信号转导途径，CsCam7和CsCam12的基因表达均显著增加。基因表达分析表明，接种后CS-20强烈增强了PR3、LOX1、PAL1、NPR1、CsCam7和CsCam12的表达。总体而言，CS-20诱导的防御反应可由黄瓜植株中的多个基因控制。
