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

Abstract

Camellia oleifera Abel is a highly valued woody edible oil tree, which is endemic to China. It has great economic value because C. oleifera seed oil contains a high proportion of polyunsaturated fatty acids. C. oleifera anthracnose caused by Colletotrichum fructicola, poses a serious threat to C. oleifera growth and yield and causes the benefit of the C. oleifera 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 C. oleifera WRKY genes are remains unknown. Here, we identified 90 C. oleifera WRKY members, which were distributed across 15 chromosomes. C. oleifera WRKY gene expansion was mainly attributed to segmental duplication. We performed transcriptomic analyses to verify the expression patterns of CoWRKYs between anthracnose-resistant and -susceptible cultivars of C. oleifera. These results demonstrated that multiple candidate CoWRKYs can be induced by anthracnose and provide useful clues for their functional studies. CoWRKY78, an anthracnose-induced WRKY gene, was isolated from C. oleifera. It was significantly down-regulated in anthracnose-resistant cultivars. Overexpression of CoWRKY78 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 (NtSOD and NtPOD), pathogen challenge (NtPAL), and pathogen defense (NtPR1, NtNPR1, and NtPDF1.2) were altered in the CoWRKY78-overexpressing plants. These findings increase our understanding of the CoWRKY genes and lay the foundation for the exploration of anthracnose resistance mechanisms and expedite the breeding of anthracnose-resistant C. oleifera cultivars.

The role of WRKY transcription factors, FaWRKY29 and FaWRKY64, for regulating Botrytis fruit rot resistance in strawberry (Fragaria × ananassa Duch.)

“…WRKY transcription factors (TFs) play a significant role in regulating plant developmental processes, particularly in biotic and abiotic stress responses in plants, including Arabidopsis , rice, and tomato [ 26 , 27 ]. WRKY TFs have been reported as modulators of plant immune responses against various pathogens, including B. cinerea [ 28 – 30 ]. Camellia oleifera WRKY78 was significantly low in expression in anthracnose-resistant cultivars.…”

“…Camellia oleifera WRKY78 was significantly low in expression in anthracnose-resistant cultivars. Reduced anthracnose resistance was observed in CoWRKY78 overexpression tobacco transgenic plants, exhibiting lower superoxide dismutase and peroxidase activities [ 28 ]. The promoter region of Morus indica WRKY53 is induced by salicylic acid (SA).…”