An integrated approach to in-depth understanding of CYP83B1’s function in Arabidopsis

Glucosinolates (GS) are a class of secondary metabolites with important roles in plant defense. Plant defense is regulated by multiple signal transduction pathways and GS biosynthesis has been shown to respond to the signaling molecule jasmonic acid. GS may also influence plant growth and development. The GS content and composition in Arabidopsis vary in the different organs. Indole GS is derivated from tryptophan, catalysed by three cytochrome P450 enzymes, CYP79B2, CYP79B3, and CYP83B1, which directed the precursor indole-3-acetaldoxime (IAOx) towards indole GS. IAOx is an important branch point, acting as an intermediate for the biosynthetic pathway indole-3-acetic acid (IAA) and camalexin. CYP83B1 loss of function mutant displays characteristic phenotypes such as, elongated hypocotyls and adventitious roots. Another characteristic was the development of necrotic lesions when grown on soil. A comprehensive study including microarray analysis and metabolite analysis have been performed, and provide in-depth understanding of the function of CYP83B1. The CYP83B1 mutant plants had reduced indole GS level. Preliminary data showed that, the CYP83B1 mutant is more sensitive to ABA than wt, suggesting a connection between ABA signaling and GS biosynthesis.