Physiological and transcriptomic analyses of brassinosteroid function in kiwifruit root

Abstract Kiwifruit is popular among consumers, but its roots are sensitive to the surrounding environment and cannot efficiently use water and nutrients, leading to weak plant growth and relatively lower fruit yield and quality. Although brassinosteroid (BR) plays a critical role in promoting kiwifruit root growth, its regulatory mechanism is still unclear. Here we reported the inhibition of root growth at the physiological level when endogenous brassinosteroid level was reduced by its biosynthesis inhibitor brassinazole (BRZ), whereas exogenous application of BR increased root elongation and lateral root and root hair growth. Genome-wide transcriptome analysis results indicated that BR and BRZ altered the expression levels of some genes in kiwifruit roots. The data show that BR promotes root development by regulating genes involved in auxin signal transduction. Our study demonstrates the important role of BR in kiwifruit root growth.