Identification of Susceptibility Genes for Fusarium oxysporum in Cucumber via Comparative Proteomic Analysis.

Jun Xu,Qianqian Xian,Jingping Dong,Ningyuan Zhang,Ke Wang,Xuehao Chen

doi:10.3390/genes12111781

Abstract

Fusarium wilt (FW) in cucumber (Cucumis sativus L.), caused by Fusarium oxysporum f. sp. cucumerinum (Foc), poses a major threat to cucumber growth and productivity. However, lack of available natural resistance resources for FW restricts the breeding of resistant cultivars via conventional approaches. Susceptibility (S) genes in susceptible host plants facilitate infection by the pathogen and contribute to susceptibility. Loss of function of these S genes might provide broad-spectrum and durable disease resistance. Here, we screened S genes via comparative proteomic analysis between cucumber cultivars Rijiecheng and Superina, which exhibited resistance and high -susceptibility to FW, respectively. We identified 210 and 243 differentially regulated proteins (DRPs) in the Rijiecheng and Superina, respectively, and further found that 32 DRPs were predominantly expressed in Superina and significantly up-regulated after Foc inoculation. Expression verification found that TMEM115 (CsaV3_5G025750), encoding a transmembrane protein, TET8 (CsaV3_2G007840), encoding function as a tetraspanin, TPS10 (CsaV3_2G017980) encoding a terpene synthase, and MGT2 (CsaV3_7G006660), encoding a glycosyltransferase, were significantly induced in both cultivars after Foc infection but were induced to a higher expression level in Superina. These candidate genes might act as negative regulators of FW resistance in cucumber and provide effective FW-susceptibility gene resources for improving cucumber FW resistance through breeding programs.

Highlights

We used the Fusarium oxysporum f. sp. cucumerinum (Foc) fused with GFP green fluorescent protein (Foc-GFP) to inoculate Rijiecheng and Superina roots and found a markedly larger number of mycelia on the surface of Superina roots relative to Rijiecheng by 96 h after Foc-GFP inoculation (Figure 1B), suggested that Superina was highly susceptible to cucumber Fusarium wilt (FW), consistent with the disease symptoms
We used the Foc fused with GFP green fluorescent protein (FocGFP) to inoculate Rijiecheng and Superina roots and found a markedly larger number of mycelia on the surface of Superina roots relative to Rijiecheng by 96 h after Foc-GFP inocof 12 ulation (Figure 1B), suggested that Superina was highly susceptible to cucumber FW,5consistent with the disease symptoms
On the basis of the expression analysis, we further identified that the genes TMEM115, TET8, TPS10, and MGT2 were significantly induced in both Rijiecheng and Superina but induced to a greater extent in Superina than in Rijiecheng, suggesting that these candidate gene might relate to the FW-susceptibility of Superina (Figure 5)

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Cucumber (C. sativus L.) is one of the most economically important vegetable crops cultivated worldwide [1]. Cucumber Fusarium wilt (FW) is a typical soil-borne and destructive fungal disease caused by F.oxysporum f. Cucumerinum (Foc) [2], which severely restricts cucumber growth and yield [3,4,5,6]. When the Foc pathogen successfully invades the plant it wilts of the leaves or even the entire plant, often leading to plant death several days or weeks after infection; it is usually considered as the most severe biotic factor limiting global cucumber production [7] Cucumber Fusarium wilt (FW) is a typical soil-borne and destructive fungal disease caused by F.oxysporum f. sp. cucumerinum (Foc) [2], which severely restricts cucumber growth and yield [3,4,5,6].

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Conclusion