Biological control agents colonize litchi fruit during storage and stimulate physiological responses to delay pericarp browning

Li Zheng; Shilian Huang; Jiehao Huang; Yizhen Deng; Zhenxian Wu; Zide Jiang; Guohui Yu

doi:10.3389/fmicb.2022.1093699

Biological control agents colonize litchi fruit during storage and stimulate physiological responses to delay pericarp browning

Front Microbiol. 2023 Jan 5:13:1093699. doi: 10.3389/fmicb.2022.1093699. eCollection 2022.

Authors

Li Zheng^{1

2}, Shilian Huang³, Jiehao Huang¹, Yizhen Deng², Zhenxian Wu⁴, Zide Jiang², Guohui Yu¹

Affiliations

¹ Key Laboratory of Green Prevention and Control on Fruits and Vegetables in South China, Ministry of Agriculture and Rural Affairs, Guangdong University Key Laboratory for Sustainable Control of Fruit and Vegetable Diseases and Pests, Innovative Institute for Plant Health, College of Agriculture and Biology, Zhongkai University of Agriculture and Engineering, Guangzhou, China.
² Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Department of Plant Pathology, South China Agricultural University, Guangzhou, China.
³ Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
⁴ Guangdong Provincial Key Laboratory of Postharvest Science of Fruit and Vegetables, College of Horticulture, Engineering Research Center for Postharvest Technology of Horticultural Crops in South China, South China Agricultural University, Ministry of Education, Guangzhou, China.

Abstract

Introduction: Litchi is an economically important fruit in subtropical countries, but pericarp browning can limit its shelf life outside of controlled storage conditions. Effective and sustainable biological control strategies are needed to protect fruit against postharvest browning.

Results and discussion: In this study, we show that the four bacterial strains Bacillus licheniformis HS10, B. amyloliquefaciens LI24 and PP19, and Exiguobacterium acetylicum SI17 can delay fruit browning in both laboratory trials (LTs) and field plus laboratory trials (FLTs). Strains HS10, LI24, PP19 and SI17 showed 47.74%, 35.39%, 33.58% and 32.53% browning-inhibitory efficacy respectively at 180 h in LT. Litchi sarcocarp interior sourced isolate SI17 showed 74.05% inhibit-brown efficacy at 216 h in FLTs, performing better in FLT than in LT. Furthermore, strains PP19 and SI17 colonized the fruit pericarp and increased total phenolic and anthocyanin contents but decreased peroxidase and polyphenol oxidase activity. This is the first report of E. acetylicum (SI17) and B. licheniformis (HS10) strains acting as biological control agents (BCAs) to delay postharvest browning in litchi fruit. We conclude that PP19 and SI17 are promising BCAs against fruit browning, and their application could be effective for prolonging the shelf life of harvested litchi fruit.

Keywords: anthocyanin content; biocontrol agents; colonization; delayed browning; enzyme activity; litchi fruit.