AUTHOR=Liu Mei , Kang Baoshan , Wu Huijie , Peng Bin , Liu Liming , Hong Ni , Gu Qinsheng 

TITLE=Ethylene enhances resistance to cucumber green mottle mosaic virus via the ClWRKY70-ClACO5 module in watermelon plants

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1332037

DOI=10.3389/fpls.2023.1332037

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>Ethylene (ET) is involved in plant responses to viral infection. However, its molecular mechanisms and regulatory network remain largely unknown.</p></sec><sec><title>Methods and results</title><p>In the present study, we report that cucumber green mottle mosaic virus (CGMMV) in watermelon (<italic>Citrullus lanatus</italic>) triggers ET production by inducing the expression of <italic>ClACO5</italic>, a key gene of the ET biosynthesis pathway through transcriptome data analysis and gene function validation. The knock-down of <italic>ClACO5</italic> expression through virus-induced gene silencing in watermelon and overexpressing <italic>ClACO5</italic> in transgenic <italic>Nicotiana benthamiana</italic> indicated that ClACO5 positively regulates CGMMV resistance and ET biosynthesis. The salicylic acid-responsive transcription factor gene <italic>ClWRKY70</italic> shares a similar expression pattern with <italic>ClACO5</italic>. We demonstrate that <italic>ClWRKY70</italic> directly binds to the W-box <italic>cis</italic>-element in the <italic>ClACO5</italic> promoter and enhances its transcription. In addition, <italic>ClWRKY70</italic> enhances plant responses to CGMMV infection by regulating <italic>ClACO5</italic> expression in watermelon.</p></sec><sec><title>Discussion</title><p>Our results demonstrate that the <italic>ClWRKY70</italic>-<italic>ClACO5</italic> module positively regulates resistance to CGMMV infection in watermelon, shedding new light on the molecular basis of ET accumulation in watermelon in response to CGMMV infection.</p></sec>