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Feeding on tea GH19 chitinase enhances tea defense responses induced by regurgitant derived from Ectropis grisescens
Author(s) -
Lu Xiaotong,
Wang Baohui,
Cai Xiaoming,
Chen Shenglong,
Chen Zongmao,
Xin Zhaojun
Publication year - 2020
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/ppl.13094
Subject(s) - chitinase , jasmonic acid , biology , biochemistry , plant defense against herbivory , camellia sinensis , botany , salicylic acid , food science , enzyme , gene
Multiple isoforms of chitinases participate in plant defense against outside invaders. However, the functions of hydrolase family 19 (GH19) chitinases on pest control remain largely unknown. Here we reported the isolation and functional analysis of a gene CsChi19 , which encodes a GH19 endochitinase protein of 332 amino acid residues from tea plant ( Camellia sinensis ). CsChi19 expression levels were upregulated in response to mechanical wounding, infestation by two important pests: the tea geometrid Ectropis grisescens and the tea green leafhopper Empoasca ( Matsumurasca ) onukii , a fungal pathogen Colletotrichum fructicola , and treatment with two phytohormones: jasmonic acid (JA) and salicylic acid. CsChi19 was heterologously expressed in Escherichia coli, and its catalytic function was further elucidated. The protein could hydrolyze colloidal chitin, and the optimum temperature and pH for its activity was 40°C and pH 5.0. CsChi19 were found to be toxic to tea pests when they were fed on artificial diets containing this protein. Interestingly, the regurgitant derived from E. grisescens fed with artificial diets containing CsChi19 protein induced stronger expression of CsMPK3, more JA burst, more accumulation of defense‐related secondary metabolites, and more emission of volatiles than the regurgitant derived from E. grisescens fed only with artificial diets. Our results provide first evidence that CsChi19 is involved in mediating a novel defense mechanism of tea plant through altering the composition of the regurgitant.