The Transcription Factors WRKY41 and WRKY53 Mediate Early Flowering Induced by the Novel Plant Growth Regulator Guvermectin in Arabidopsis thaliana .

Flowering is a crucial stage for plant reproductive success; therefore, the regulation of plant flowering has been widely researched. Although multiple well-defined endogenous and exogenous flowering regulators have been reported, new ones are constantly being discovered. Here, we confirm that a novel plant growth regulator guvermectin (GV) induces early flowering in . Interestingly, our genetic experiments newly demonstrated that and its homolog were involved in GV-accelerated flowering as positive flowering regulators. Overexpression of or resulted in an early flowering phenotype compared to the wild type (WT). In contrast, the double mutants showed a delay in GV-accelerated flowering. Gene expression analysis showed that flowering regulatory genes and were upregulated in GV-treated WT, , and plants, but both declined in mutants with or without GV treatment. Meanwhile, biochemical assays confirmed that and were both direct targets of WRKY41 and WRKY53. Furthermore, the early flowering phenotype of lines was abolished in the or background. Together, our results suggest that GV plays a function in promoting flowering, which was co-mediated by WRKY41 and WRKY53 acting as new flowering regulators by directly activating the transcription of and in .