The BR signaling pathway regulates primary root development and drought stress response by suppressing the expression of PLT1 and PLT2 in Arabidopsis thaliana

With the warming global climate, drought stress has become an important abiotic stress factor limiting plant growth and crop yield. As the most rapidly drought-sensing organs of plants, roots undergo a series of changes to enhance their ability to absorb water, but the molecular mechanism is unclear. In this study, we found that PLT1 and PLT2, two important transcription factors of root development in , are involved in the plant response to drought and are inhibited by BR signaling. PLT1- and PLT2-overexpressing plants showed greater drought tolerance than wild-type plants. Furthermore, we found that BZR1 could bind to the promoter of and inhibit its transcriptional activity and . and were regulated by BR signaling in root development and could partially rescue the drought sensitivity of . In addition, RNA-seq data analysis showed that BR-regulated root genes and PLT1/2 target genes were also regulated by drought; for example, , , , , were downregulated by drought and PLT1/2 but upregulated by BR treatment; , , and were downregulated by PLT1/2 but upregulated by drought and BR treatment; and was upregulated by drought and PLT1/2 but downregulated by BR treatment. Our findings not only reveal the mechanism by which BR signaling coordinates root growth and drought tolerance by suppressing the expression of PLT1 and PLT2 but also elucidates the relationship between drought and root development. The current study thus provides an important theoretical basis for the improvement of crop yield under drought conditions.