title: Proteomic Analysis Reveals the Positive Roles of the Plant-Growth-Promoting Rhizobacterium NSY50 in the Response of Cucumber Roots to Fusariumoxysporumf. sp.cucumerinumInoculation.
abstract: Plant-growth-promoting rhizobacteria (PGPR) can both improve plant growth and enhance plant resistance against a variety of environmental stresses. To investigate the mechanisms that PGPR use to protect plants under pathogenic attack, transmission electron microscopy analysis and a proteomic approach were designed to test the effects of the new potential PGPR strainPaenibacillus polymyxaNSY50 on cucumber seedling roots after they were inoculated with the destructive phytopathogenFusarium oxysporumf. sp.cucumerinum(FOC). NSY50 could apparently mitigate the injury caused by the FOC infection and maintain the stability of cell structures. The two-dimensional electrophoresis (2-DE) approach in conjunction with MALDI-TOF/TOF analysis revealed a total of 56 proteins that were differentially expressed in response to NSY50 and/or FOC. The application of NSY50 up-regulated most of the identified proteins that were involved in carbohydrate metabolism and amino acid metabolism under normal conditions, which implied that both energy generation and the production of amino acids were enhanced, thereby ensuring an adequate supply of amino acids for the synthesis of new proteins in cucumber seedlings to promote plant growth. Inoculation with FOC inhibited most of the proteins related to carbohydrate and energy metabolism and to protein metabolism. The combined inoculation treatment (NSY50+FOC) accumulated abundant proteins involved in defense mechanisms against oxidation and detoxification as well as carbohydrate metabolism, which might play important roles in preventing pathogens from attacking. Meanwhile, western blotting was used to analyze the accumulation of enolase (ENO) and S-adenosylmethionine synthase (SAMs). NSY50 further increased the expression of ENO and SAMs under FOC stress. In addition, NSY50 adjusted the transcription levels of genes related to those proteins. Taken together, these results suggest thatP. polymyxaNSY50 may promote plant growth and alleviate FOC-induced damage by improving the metabolism and activation of defense-related proteins in cucumber roots.
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University Nanjing, China.
authors.forename: Nanshan
authors.initials: N
authors.lastname: Du
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University Nanjing, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Shi
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University Nanjing, China.
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Horticulture, Shanxi Agricultural University Taigu, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China; Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversitySuqian, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Shu
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China; Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversitySuqian, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement in Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China; Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversitySuqian, China.
authors.forename: Shirong
authors.initials: S
authors.lastname: Guo
keywords: Fusarium oxysporum f. sp. cucumerinum; cucumber; plant-growth-promoting rhizobacteria; proteomics; root