Characterization of maize cytochrome p450 monooxygenases induced in response to safeners and bacterial pathogens

Plants use a diverse array of cytochrome P450 monooxygenases in their biosy nthetic and detoxification pathways. To determine the extent to which vario us maize P450s are induced in response to chemical inducers, such as naphth alic anhydride (NA), triasulfuron (T), phenobarbital, and bacterial pathoge ns (Erwinia stuartii, Acidovorax avenae), we have analyzed the response pat terns of seven P450 transcripts after treatment of seedlings with these ind ucers. Each of these P450 transcripts has distinct developmental, tissue-sp ecific, and chemical cues regulating their expression even when they encode P450s within the same biosynthetic pathway. Most notably, the CYP71C1 and CYP71C3 transcripts, encoding P450s in the DIMBOA biosynthetic pathway, are induced to the same level in response to wounding and NA treatment of youn ger seedlings and differentially in response to NA/T treatment of younger s eedlings and NA and NA/T treatment of older seedlings. NA and T induce expr ession of both CYP92A1 and CYP72A5 transcripts in older seedling shoots, wh ereas phenobarbital induces CYP92A1 expression in older seedling shoots and highly induces CYP72A5 expression in young and older seedling roots. Expre ssed sequence tag (EST) 6c06b11 transcripts, encoding an undefined P450 act ivity, are highly induced in seedling shoots infected with bacterial pathog ens.