title: Analysis of the defence-related mechanism in cucumber seedlings in relation to root colonization by nonpathogenic Fusarium oxysporum CS-20.
abstract: 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.
authors.affiliation: 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.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Pu
authors.forename: Bingyan
authors.initials: B
authors.lastname: Xie
authors.forename: Peiqian
authors.initials: P
authors.lastname: Li
authors.forename: Zhenchuan
authors.initials: Z
authors.lastname: Mao
authors.forename: Jian
authors.initials: J
authors.lastname: Ling
authors.forename: Huifang
authors.initials: H
authors.lastname: Shen
authors.forename: Jingxin
authors.initials: J
authors.lastname: Zhang
authors.forename: Ning
authors.initials: N
authors.lastname: Huang
authors.forename: Birun
authors.initials: B
authors.lastname: Lin
mesh_terms: D061046:Biological Control Agents; D018553:Cucumis sativus / Q000235:genetics* / Q000382:microbiology*; D060467:Disease Resistance / Q000235:genetics; D005670:Fusarium / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology; D018749:RNA, Plant / Q000235:genetics; D036226:Seedlings / Q000382:microbiology; D015398:Signal Transduction
chemical_list: D061046:Biological Control Agents; D010940:Plant Proteins; D018749:RNA, Plant
keywords: ISR; SAR; hydroponic chamber; indirect antagonism