Biosynthesis and emission of insect herbivory-induced volatile indole in rice.

Insect-damaged rice plants emit a complex mixture of volatiles that are highly attractive to parasitic wasps. Indole is one constituent of insect-induced rice volatiles, and is produced in plants by the enzyme indole-3-glycerol phosphate lyase (IGL). The alpha-subunit of tryptophan synthase (TSA) is the IGL that catalyses the conversion of indole-3-glycerol phosphate to indole in the alpha-reaction of tryptophan synthesis; however, TSA is only active in the complex with the beta-subunit of tryptophan synthase and is not capable of producing free indole.

Benzoxazinoid biosynthesis, a model for evolution of secondary metabolic pathways in plants.

Benzoxazinoids are secondary metabolites that are effective in defence and allelopathy. They are synthesised in two subfamilies of the Poaceae and sporadically found in single species of the dicots. The biosynthesis is fully elucidated in maize; here the genes encoding the enzymes of the pathway are in physical proximity.

Characterisation of the tryptophan synthase alpha subunit in maize.

Background: In bacteria, such as Salmonella typhimurium, tryptophan is synthesized from indole-3-glycerole phosphate (IGP) by a tryptophan synthase alphabetabetaalpha heterotetramer. Plants have evolved multiple alpha (TSA) and beta (TSB) homologs, which have probably diverged in biological function and their ability of subunit interaction. There is some evidence for a tryptophan synthase (TS) complex in Arabidopsis.

Elucidation of the final reactions of DIMBOA-glucoside biosynthesis in maize: characterization of Bx6 and Bx7.

Benzoxazinoids were identified in the early 1960s as secondary metabolites of the grasses that function as natural pesticides and exhibit allelopathic properties. Benzoxazinoids are synthesized in seedlings and stored as glucosides (glcs); the main aglucone moieties are 2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA) and 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA). The genes of DIBOA-glc biosynthesis have previously been isolated and the enzymatic functions characterized.