title: Common and unique cis-acting elements mediate xanthotoxin and flavone induction of the generalist P450 CYP321A1.
abstract: How polyphagous herbivores up-regulate their counterdefense genes in response to a broad range of structurally different allelochemicals remains largely unknown. To test whether this is accomplished by having more allelochemical-response elements or the similar number of functionally more diverse elements, we mapped out the cis-acting elements mediating the induction of the allelochemical-metabolizing CYP321A1 from the generalist Helicoverpa zea by xanthotoxin and flavone, two structurally distinct allelochemicals with very different encounter rate by this species. Seven xanthotoxin-responsive elements were localized by analyzing promoter activities of varying length of CYP321A1 promoter in H. zea fatbody cells. Compared with the 5 flavone-responsive elements mapped out previously, there are four common elements (1 essential element, 2 enhancers, and 1 negative element) mediating induction of CYP321A1 by both of the two allelochemicals. The remaining four elements (3 enhancers and 1 negative element), however, only regulate induction of CYP321A1 by either of the two allelochemicals. Co-administration of the two allelochemicals resulted in an induction fold that is significantly lower than the expected additive value of the two allelochemicals. These results indicate that xanthotoxin- and flavone-induced expressions of CYP321A1 are mediated mainly by the functionally more diverse common elements although the allelochemical-unique elements also play a role.
authors.affiliation: 1] Key Laboratory of Plant Protection Resources and Pest Integrated Management, Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China [2] Department of Entomology and BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Chunni
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Entomology and BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wong
authors.affiliation: Key Laboratory of Plant Protection Resources and Pest Integrated Management, Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Yalin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: USDA-ARS Crop Genetics and Breeding Research Unit, Tifton, GA 31793, USA.
authors.forename: Xinzhi
authors.initials: X
authors.lastname: Ni
authors.affiliation: Department of Entomology and BIO5 Institute, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Xianchun
authors.initials: X
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics*; D047309:Flavones / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D007306:Insecticides / Q000008:administration & dosage / Q000494:pharmacology; D007915:Lepidoptera / Q000187:drug effects / Q000201:enzymology*; D008730:Methoxsalen / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012045:Regulatory Sequences, Nucleic Acid / Q000187:drug effects / Q000235:genetics
chemical_list: D047309:Flavones; D007306:Insecticides; D003577:Cytochrome P-450 Enzyme System; C492993:cytochrome P-450 321A1, Helicoverpa zea; C043562:flavone; D008730:Methoxsalen