Abstract: Sorghum is considered to be an allelopathic crop species, producing phytotoxins such as the lipid benzoquinone sorgoleone (2-hydroxy-5-methoxy-3-[(Z,Z)-8?,11?,14?-pentadecatriene]-p-benzoquinone) which likely accounts for much of its allelopathic properties. Prior investigations into the biosynthesis of sorgoleone have suggested the participation of one or more alkylresorcinol synthases (ARS), which are type III polyketide synthases (PKS) that produce 5-alkylresorcinols using medium to long-chain fatty acyl-CoA starter units via iterative condensations with malonyl-CoA. Current evidence suggests that sorgoleone biosynthesis occurs exclusively in root hair cells, involving the synthesis of a 5-pentadecatrienyl resorcinol intermediate derived from an unusual 16:3 fatty acyl-CoA starter unit.

Abstract: This invention relates to an O-methyltransferase gene cloned from sorghum, the sorghum O-methyltransferase-3 gene, SbOMT3. Quantitative real-time RT-PCR and recombinant enzyme studies with putative O-methyltransferase sequences obtained from an EST data set from sorghum have led to the identification of the novel root hair-specific O-methyltransferase designated SbOMT3. Transgenic plants which express SbOMT3 can convert resveratrol into pterostilbene in planta. SbOMT3 is also involved in the biosynthesis of sorgoleone.

Abstract: The present invention relates to the isolation and use of an allene oxide synthase enzyme as an antioxidant of lipid peroxides in biological systems. It is based, at least in part, on the discovery that antioxidation is accomplished enzymatically by RPP, a species of allene oxide synthase, in guayule, and on the discovery that the allene oxide synthase RPP disrupts the chain reaction and propagation steps of lipid peroxidation. The present further invention relates to the use of an allene oxide synthase to result in a time-dependent disappearance of conjugated dienes (i.e. lipid hydroperoxides). The allene oxide synthase rapidly converts free or esterified fatty acid peroxides or hydroperoxides into their corresponding epoxides, which, in turn are converted to ketols. The lipid peroxide and hydroperoxide substrates for this enzyme are known to be toxic to biological organisms and can generate additional peroxides by chain propagation reactions.

Abstract: Guayule rubber particles, contain several characteristic proteins. The most abundant of these proteins, the rubber particle protein (RPP) has been shown to be a non-monooxygenase, cytochrome P450, heme-binding protein that is necessary for rubber biosynthesis. A full-length cDNA clone for guayule RPP has been isolated, sequenced and characterized. The pRPP30 coding sequence is transferable to other prokaryotic or eukaryotic host organisms wherein the RPP DNA will be expressed to produce functional RPP for rubber biosynthesis.