Transcriptome analysis reveals ethylene-mediated defense responses to Fusarium oxysporum f. sp. cucumerinum infection in Cucumis sativus L.

Abstract

Background: Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (Foc), is a severe disease affecting cucumber (Cucumis sativus L.) production worldwide, but mechanisms underlying Fusarium wilt resistance in cucumber remain unknown. To better understand of the defense mechanisms elicited in response to Foc inoculation, RNA sequencing-based transcriptomic profiling of responses of the Fusarium wilt-resistant cucumber line 'Rijiecheng' at 0, 24, 48, 96, and 192 h after Foc inoculation was performed. Results: We identified 4116 genes that were differentially expressed between 0 h and other time points after inoculation. All ethylene-related and pathogenesis-related genes from the differentially expressed genes were filtered out. Real-time PCR analysis showed that ethylene-related genes were induced in response to Foc infection. Importantly, after Foc infection and exogenous application of ethephon, a donor of ethylene, the ethylene-related genes were highly expressed. In response to exogenous ethephon treatment in conjunction with Foc inoculation, the infection resistance of cucumber seedlings was enhanced and endogenous ethylene biosynthesis increased dramatically. Conclusion: Collectively, ethylene signaling pathways play a positive role in regulating the defense response of cucumber to Foc infection. The results provide insight into the cucumber Fusarium wilt defense mechanisms and provide valuable information for breeding new cucumber cultivars with enhanced Fusarium wilt tolerance.

Transcriptome Profiling of Cucumber (Cucumis sativus L.) Early Response to Pseudomonas syringae pv. lachrymans

“…In the study performed by Wang et al [22], strong expression of the PR4 gene was observed in response to fungus C. cassiicola in both resistant and susceptible lines. Other authors also pointed out activation of this gene in cucumber response to various pathogens [16,23,47].…”

“…In cucumber, such an approach was applied to study response to viruses, including Cucurbit Chlorotic Yellows Virus (CCYV) and Cucumber Mosaic Virus (CMV) [17,18], oomycete pathogens Pseudoperonospora cubensis and Phytophthora melonis [19][20][21], and fungal pathogens like Botrytis cinerea, Corynespora cassiicola, Fusarium oxysporum f. sp. cucumerinum, Sphaerotheca fuliginea, and Alternaria cucumeriana [16,[22][23][24][25]. RNA-seq was also used to investigate cucumber response to aphid and spider-mite infestations [26,27].…”

Identification of miRNA-Target Gene Pairs Responsive to Fusarium Wilt of Cucumber via an Integrated Analysis of miRNA and Transcriptome Profiles

“…Followed the inoculation phenotypes and sequencing verification, the Foc strain was confirmed and then cultured in potato dextrose broth in plates on a shaker (180 rpm) at 28 °C for 3 days. The concentration was adjusted to 10 6 spores/mL using sterile distilled water prior to the inoculation of 14-day large cucumber seedlings at second true-leaf stage via a published dip-inoculation method [ 22 ]. Three replicates of seedling roots were harvested at 0, 24, 48, 96, and 192 h after the Foc inoculation.…”

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

“…The Foc acted as a typical soil-borne and destructive fungal disease, which firstly infected the roots of cucumber growth process in field and induced the responsive genes to defense FW. We used the cucumber seedlings to inoculate with Foc using the dipinoculation method [6]. The Foc strain was propagated on potato dextrose agar (PDA) medium-containing plates at 28 • C for 4 d, then cultured in potato dextrose broth (PDB) medium on a shaker at 180 rpm at 28 • C for 3 d. The spore suspension was adjusted to 10ˆ6 spores/mL using sterile distilled water for inoculation of the cucumber seedlings.…”

“…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].…”