Molecular Cloning and Function of Novel Cytochrome P450 Related to Metabolism of Herbicides from Lolium Rigidum

摘要

The cytochrome P450 ( CYP) superfamily is widely distributed in various species and participates in a wide range of oxygenation reactions of diverse liphophilic substrates including pesticides and environmental contaminants. In high plants, there aremany kinds of P450 genes. For example, there are 286 P450 genes in Arabidopsis thaliana and 458 P450 genes in rice ( Oryza saliva L. cv. Nipponbare ). These P450 species mostly partici- pate in biosynthesis of secondary metabolites, e. g. lignins, fattyacids, gibberellic acids, brassinosteroids, jas-monic acid, flavonoids, cyanogenic glucosides, alkaloids, and so on. They are also involved in the metabolism of foreign compounds which may encounter in the environment, including agricultural pesticidesand herbicides. Cytochrome P450 metabolism has been implicated as being largely responsible for detoxification of herbicides in a variety of crop species ( selective toxicity). Up to now, more than 500 cytochrome P450 genes have been cloned from higher plants but the enzymatic function of most of these genes is unknown . Recent years, it was proved that some of plant P450 enzymes are involved in metabolism of herbicides. For example, CYP71A10 could metabolize phenylurea herbicides in Glysine max. CYP71A11 of Nicotiana tabacum and CYP81B1 of Helianthus tuberrosus were involved in chlorotoluron metabolism. CYP71B11 could metabolize sulfonylurea herbicides in Arabidopsis thaliana. Lolium rigidum has many kinds of biotypes (e. g. SLR31) that have high activities in metabolism of herbicides to show cross-resistance to multiple herbicides. The present study aimed at molecular cloning of novel cytochrome P450 species from L. rigidum seedlings. The cloned cDNAs of novel cytochrome P450 species are characterized in enzymatic functions.