Ruttaporn Chundet1, 2Robert W. Cutler, 3Somboon Anuntalabhochai
Using a low-energy N+ / N2 + ion beam, a mutant variety of Thai jasmine rice (Oryza sativa L. cv. KDML105) was created with distinctive black seeds, short-in-stature and photoperiod insensitive. To characterize the biochemical origin of the black seed color phenotype, flavonoid and anthocyanin accumulation levels were measured as was the expression of the genes involved in the anthocyanin biosynthesis pathway. Anthocyanin synthase, an enzyme not expressed in the original variety, was found to be expressed in all mutant tissues in addition to the two enzymes F3��?H and F3��?5��?H which initiate the alternative color pathways. The expression of MYC or Ra, a known anthocyanin upregulator, in the mutant is proposed to be caused by the inactivation of a repressor gene present in the original variety which was inactivated in the mutant by the ion beam bombardment. The increased production of anthocyanin, a known antioxidant, and the additional growing season due to the high-light insensitivity mark this mutant as a possible new improved crop variety for Thai rice cultivation.
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