Knock out of transcription factor WRKY53 thickens sclerenchyma cell walls, confers bacterial blight resistance

Abstract

Plant cell walls are the first physical barrier against pathogen invasion, and plants thicken the cell wall to strengthen it and restrain pathogen infection. Bacterial blight is a devastating rice (Oryza sativa) disease caused by Xanthomonas oryzae pv. oryzae (Xoo), which typically enters the rice leaf through hydathodes and spreads throughout the plant via the xylem. Xoo interacts with cells surrounding the xylem vessel of a vascular bundle, but whether rice strengthens the sclerenchyma cell walls to stop pathogen proliferation is unclear. Here, we found that a WRKY protein, OsWRKY53, negatively confers resistance to Xoo by strengthening the sclerenchyma cell walls of the vascular bundle. OsMYB63 acts as a transcriptional activator and promotes the expression of three secondary cell wall-related cellulose synthase genes to boost cellulose accumulation, resulting in thickened sclerenchyma cell walls. Both OsWRKY53 and OsMYB63 are abundantly expressed in sclerenchyma cells of leaf vascular bundles. OsWRKY53 functions as a transcriptional repressor and acts genetically upstream of OsMYB63 to suppress its expression. The OsWRKY53-overexpressing and OsMYB63 knockout plants had thinner sclerenchyma cell walls, showing susceptibility to Xoo, while the OsWRKY53 knockout and OsMYB63-overexpressing plants had thicker sclerenchyma cell walls, exhibiting resistance to Xoo. These results suggest that modifying these candidate genes provides a strategy to improve rice resistance to bacterial pathogens.

OsWRKY53 Promotes Abscisic Acid Accumulation to Accelerate Leaf Senescence and Inhibit Seed Germination by Downregulating Abscisic Acid Catabolic Genes in Rice

“…OsWRKY53 has been reported to play critical roles in rice growth and development by regulating plant architecture and seed size (Tian et al, 2017(Tian et al, , 2021. It also plays roles in plant responses to biotic stress, including pathogens or herbivore, and abiotic stress, such as wounding (Chujo et al, 2007;Yoo et al, 2014;Hu et al, 2015;Xie et al, 2021). In this study, we found that OsWRKY53 promotes premature leaf senescence and inhibits seed germination by modulating ABA metabolism.…”

“…Plant materials used in this study were OsWRKY53overexpressing (OsWRKY53-oe) plants, OsWRKY53 (oswrky53) mutants, OsWRKY53-GFP plants, and the corresponding wildtype cultivar Zhonghua 11 (ZH11) (Xie et al, 2021). The seeds were sown on seedbeds, and 1 month later, the seedlings were transplanted to the paddy field.…”

“…cDNAs were synthesized with Superscript II reverse transcriptase (Invitrogen, United States) according to the manufacturer's protocol. Quantitative real-time PCR (RT-qPCR) was performed using LightCycler 480 SYBR Green I Master (Roche, Switzerland) in the ABI 7500 Real-Time PCR System (Applied Biosystems, United States) as described previously (Xie et al, 2021). Genespecific primers were designed using primer analysis software Primer Express version 3.0 (Applied Biosystems, United States).…”

“…Chromatin immunoprecipitation assay was performed as described previously (Xie et al, 2021). Briefly, chromatin was extracted and fragmented via ultrasound to 200-400 bp.…”

PpMYB36 Encodes a MYB-Type Transcription Factor That Is Involved in Russet Skin Coloration in Pear (Pyrus pyrifolia)

“…Hence, the higher expression levels of PpMYB36 in russet skin pears is due to the W-box insertion in the promoter region. The W-box is a WRKY protein binding element ( Xie et al, 2021 ). Several recent studies have shown that WRKY transcription factors can bind to the promoter regions of MYB genes that regulate physiological and biochemical functions in plants ( Lloyd et al, 2017 ; Liu et al, 2019 ).…”