An EjbHLH14-EjHB1-EjPRX12 module is involved in methyl jasmonate alleviation of chilling-induced lignin deposition in loquat fruit.

Abstract

Loquat fruit are susceptible to chilling injuries induced by postharvest storage at low temperature. The major symptoms are increased lignin content and flesh firmness, which cause a leathery texture. Pretreatment with methyl jasmonate (MeJA) can alleviate this low-temperature-induced lignification, but the mechanism is not understood. In this study, we characterized a novel class III peroxidase, EjPRX12, and studied its relationship to lignification. Transcript levels of EjPRX12 were attenuated following MeJA pretreatment, consistent with the reduced lignin content in fruit. In vitro enzyme activity assay indicated that EjPRX12 polymerized sinapyl alcohol, and overexpression of EjPRX12 in Arabidopsis promoted lignin accumulation, indicating that it plays a functional role in lignin polymerization. We also identified an HD-ZIP transcription factor, EjHB1, repressed by MeJA pretreatment, which directly bound to and significantly activated the EjPRX12 promoter. Overexpression of EjHB1 in Arabidopsis promoted lignin accumulation with induced expression of lignin-related genes, especially AtPRX64. Furthermore, a JAZ-interacting repressor, EjbHLH14, was characterized, and it is proposed that MeJA pretreatment caused EjbHLH14 to be released to repress the expression of EjHB1. These results identified a novel regulatory pathway involving EjbHLH14-EjHB1-EjPRX12 and revealed the molecular mechanism whereby MeJA alleviated lignification of loquat fruit at low temperature.

• Authors: Mengxue Zhang, Yanna Shi, Zimeng Liu, Yijin Zhang, Xueren Yin, Zihao Liang, Yiqing Huang, Donald Grierson, Kunsong Chen
• Journal: Journal of experimental botany (J Exp Bot) Vol. 73 Issue 5 Pg. 1668-1682 (03 02 2022) ISSN: 1460-2431 [Electronic] England
• PMID: 34893804 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: [email protected].

Chemical References

• Acetates
• Cyclopentanes
• Oxylipins
• Plant Extracts
• Plant Proteins
• loquat extract
• Lignin
• methyl jasmonate

Topics

• Acetates
• Cyclopentanes
• Eriobotrya (genetics)
• Fruit (genetics, metabolism)
• Gene Expression Regulation, Plant
• Lignin (metabolism)
• Oxylipins
• Plant Extracts
• Plant Proteins (genetics, metabolism)