Abstract Sugars, the primary carbohydrates produced by photosynthesis, are essential for metabolism and serve as signaling molecules that regulate growth and stress responses. Although WRKY transcription factors are recognized for their role in mediating responses to abiotic and biotic stresses, their role in plant growth remains largely unknown. To identify components of sugar signaling, we focused on transcription factors influenced by sugar and identified WRKY20 as a positive regulator in Arabidopsis thaliana. Our findings revealed that WRKY20 expression is rapidly induced by glucose and sucrose but repressed during carbon starvation, with this regulation dependent on the glucose sensor HXK1. By integrating genetic, physiological, and molecular evidence, we demonstrated that WRKY20 directly activates genes involved in anthocyanin biosynthesis and starch biosynthesis, thereby promoting pigment accumulation and starch production. Notably, overexpression of WRKY20 resulted in significant phenotypic changes, including larger seeds, narrower cotyledons, reduced shade avoidance responses, earlier flowering, and premature senescence. Mechanistically, WRKY20 interacted with KIN10, the key catalytic subunit of SnRK1, but not HXK1, thus linking WRKY20 directly to sugar and energy status. Our study establishes WRKY20 as a regulator of sugar signaling fine-tuning multiple metabolic, growth, and developmental processes.
Ma et al. (Mon,) studied this question.