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Article|15 Oct 2019|OPEN
Comparative proteomic analysis of cucumber powdery mildew resistance between a single-segment substitution line and its recurrent parent
Xuewen Xu1, Xueli Liu1, Yali Yan1, Wei Wang1, Kiros Gebretsadik1, Xiaohua Qi1, Qiang Xu1 & Xuehao Chen1,
1School of Horticulture and Plant Protection, Yangzhou University, 225009 Yangzhou, Jiangsu, China

Horticulture Research 6,
Article number: 19115 (2019)
doi: 10.1038/hortres.2019.115
Views: 195

Received: 13 Nov 2018
Revised: 04 Jul 2019
Accepted: 27 Aug 2019
Published online: 15 Oct 2019

Abstract

Powdery mildew (PM) is considered a major cause of yield losses and reduced quality in cucumber worldwide, but the molecular basis of PM resistance remains poorly understood. A segment substitution line, namely, SSL508-28, was developed with dominant PM resistance in the genetic background of PM-susceptible cucumber inbred line D8. The substituted segment contains 860 genes. An iTRAQ-based comparative proteomic technology was used to map the proteomes of PM-inoculated and untreated (control) D8 and SSL508-28. The number of differentially regulated proteins (DRPs) in SSL508-28 was almost three times higher than that in D8. Fourteen DRPs were located in the substituted segment interval. Comparative gene expression analysis revealed that nodulin-related protein 1 (NRP1) may be a good candidate for PM resistance. Gene Ontology enrichment analysis showed that DRPs functioning in tetrapyrrole biosynthetic process, sulfur metabolic process and cell redox homeostasis were specifically enriched in the resistant line SSL508-28. DRPs categorized in the KEGG term photosynthesis increased in both lines upon PM infection, suggesting that the strategies used by cucumber may be different from those used by other crops to react to PM attacks at the initial stage. The measurement of hydrogen peroxide and superoxide anion production and net photosynthetic rate were consistent with the changes in protein abundance, suggesting that the proteomic results were reliable. There was a poor correlation between DRPs measured by iTRAQ and the corresponding gene expression changes measured by RNA-seq with the same experimental design. Taken together, these findings improve the understanding of the molecular mechanisms underlying the response of cucumber to PM infection.