Effect of ethylene production by four pathogenic fungi on the postharvest diseases of green pepper (Capsicum annuum L.)

Shuang Gu; Lin Xie; Qiuyue Guan; Xuerong Sheng; Yonggang Fang; Xiangyang Wang

doi:10.1016/j.ijfoodmicro.2024.110729

Effect of ethylene production by four pathogenic fungi on the postharvest diseases of green pepper (Capsicum annuum L.)

Int J Food Microbiol. 2024 Apr 30:418:110729. doi: 10.1016/j.ijfoodmicro.2024.110729. Online ahead of print.

Authors

Shuang Gu¹, Lin Xie², Qiuyue Guan², Xuerong Sheng², Yonggang Fang², Xiangyang Wang³

Affiliations

¹ Key Laboratory of Fruits and Vegetables Postharvest and Processing Technology Research of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China; Key Laboratory for Food Microbial Technology of Zhejiang Province, Zhejiang Gongshang University, Hangzhou 310018, PR China.
² Key Laboratory of Fruits and Vegetables Postharvest and Processing Technology Research of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China.
³ Key Laboratory of Fruits and Vegetables Postharvest and Processing Technology Research of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, PR China. Electronic address: wangxiangyang@zjsu.edu.cn.

PMID: 38696986
DOI: 10.1016/j.ijfoodmicro.2024.110729

Abstract

Ethylene produced by plants generally induces ripening and promotes decay, whereas the effect of ethylene produced by pathogens on plant diseases remains unclear. In this study, four ethylene-producing fungi including Alternaria alternata (A. alternata, Aa), Fusarium verticilliodes (F. verticillioides, Fv), Fusarium fujikuroi 1 (F. fujikuroi 1, Ff-1) and Fusarium fujikuroi 2 (F. fujikuroi 2, Ff-2) were severally inoculated in potato dextrose broth (PDB) media and postharvest green peppers, the ethylene production rates, disease indexes and chlorophyll fluorescence parameters were determined. The results showed that Ff-2 and Fv in the PDB media had the highest and almost the same ethylene production rates. After inoculation with green peppers, Ff-2 treated group still exhibited the highest ethylene production rate, whereas Aa treated group had a weak promotion effect on ethylene production. Moreover, the ethylene production rate of green peppers with mechanical injury was twice that without mechanical injury, and the ethylene production rates of green peppers treated with Aa, Ff-1, Ff-2 and Fv were 1.2, 2.6, 3.8 and 2.8 folds than those of green peppers without treatment, respectively. These results indicated that pathogen infection stimulated the synthesis of ethylene in green peppers. Correlation analysis indicated that the degreening of Fusarium-infected green pepper was significantly positively correlated with the ethylene production rate of green pepper, whereas the disease spot of Aa-infected green pepper had a significant positive correlations with the ethylene production rate of green peppers. Chlorophyll fluorescence results showed that the green peppers already suffered from severe disease after being infected with fungi for 4 days, and Fusarium infection caused early and serious stress, while the harm caused by A. alternata was relatively mild at the early stage. Our results clearly showed that α-keto-γ-methylthiobutyric acid (KMBA)-mediated ethylene synthesis was the major ethylene synthesis pathway in the four postharvest pathogenic fungi. All the results obtained suggested that ethylene might be the main infection factor of Fusarium spp. in green peppers. For pathogenic fungi, stimulating green peppers to produce high level of ethylene played a key role in the degreening of green peppers.

Keywords: A. alternata; Ethylene; Fusarium spp.; Green peppers; KMBA; Postharvest disease.