Bus, a bushy arabidopsis CYP79F1 knockout mutant with abolished synthesis of short-chain aliphatic glucosinolates

A new mutant of Arabidopsis designated bus1-1 (for bushy), which exhibited a bushy phenotype with crinkled leaves and retarded vascularization, was ch aracterized. The phenotype was caused by an En-l insertion in the gene CYP7 9F1. The deduced protein belongs to the cytochrome P450 superfamily. Becaus e members of the CYP79 subfamily are believed to catalyze the oxidation of amino acids to aldoximes, the initial step in glucosinolate biosynthesis, w e analyzed the level of glucosinolates in a CYP79F1 null mutant (bus1-1f) a nd in an overexpressing plant. Short-chain glucosinolates derived from meth ionine were completely lacking in the null mutant and showed increased leve ls in the overexpressing plant, indicating that CYP79F1 uses short-chain me thionine derivatives as substrates, In addition, the concentrations of indo le-3-ylmethyl-glucosinolate and the content of the auxin indole-3-acetic ac id and its precursor indole-3-acetonitrile were increased in the bus1-1f mu tant. Our results demonstrate for the first time that the formation of gluc osinolates derived from methionine is mediated by CYP79F1 and that knocking out this cytochrome P450 has profound effects on plant growth and developm ent.