AUTHOR=Li Jingbin , Xiong Chaowei , Ruan Dong , Du Wei , Li He , Ruan Chengjiang 

TITLE=Identification of Camellia oleifera WRKY transcription factor genes and functional characterization of CoWRKY78

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1110366

DOI=10.3389/fpls.2023.1110366

ISSN=1664-462X

ABSTRACT=<p><italic>Camellia oleifera</italic> Abel is a highly valued woody edible oil tree, which is endemic to China. It has great economic value because <italic>C. oleifera</italic> seed oil contains a high proportion of polyunsaturated fatty acids. <italic>C. oleifera</italic> anthracnose caused by <italic>Colletotrichum fructicola</italic>, poses a serious threat to <italic>C. oleifera</italic> growth and yield and causes the benefit of the <italic>C. oleifera</italic> industry to suffer directly. The WRKY transcription factor family members have been widely characterized as vital regulators in plant response to pathogen infection. Until now, the number, type and biological function of <italic>C. oleifera WRKY</italic> genes are remains unknown. Here, we identified 90 C<italic>. oleifera</italic> WRKY members, which were distributed across 15 chromosomes. <italic>C. oleifera WRKY</italic> gene expansion was mainly attributed to segmental duplication. We performed transcriptomic analyses to verify the expression patterns of <italic>CoWRKYs</italic> between anthracnose-resistant and -susceptible cultivars of <italic>C. oleifera</italic>. These results demonstrated that multiple candidate <italic>CoWRKY</italic>s can be induced by anthracnose and provide useful clues for their functional studies. <italic>CoWRKY78</italic>, an anthracnose-induced <italic>WRKY</italic> gene, was isolated from <italic>C. oleifera</italic>. It was significantly down-regulated in anthracnose-resistant cultivars. Overexpression of <italic>CoWRKY78</italic> in tobacco markedly reduced resistance to anthracnose than WT plants, as evidenced by more cell death, higher malonaldehyde content and reactive oxygen species (ROS), but lower activities of superoxide dismutase (SOD), peroxidase (POD), as well as phenylalanine ammonia-lyase (PAL). Furthermore, the expression of multiple stress-related genes, which are associated with ROS-homeostasis (<italic>NtSOD</italic> and <italic>NtPOD</italic>), pathogen challenge (<italic>NtPAL</italic>), and pathogen defense (<italic>NtPR1</italic>, <italic>NtNPR1</italic>, and <italic>NtPDF1.2</italic>) were altered in the <italic>CoWRKY78</italic>-overexpressing plants. These findings increase our understanding of the <italic>CoWRKY</italic> genes and lay the foundation for the exploration of anthracnose resistance mechanisms and expedite the breeding of anthracnose-resistant <italic>C. oleifera</italic> cultivars.</p>