Golden Indica and Japonica rice lines amenable to deregulation

Abstract

As an important step toward free access and, thus, impact of GoldenRice, a freedom-to-operate situation has been achieved for developing countries for the technology involved. Specifically, to carry the invention beyond its initial "proof-of-concept" status in a Japonica rice (Oryza sativa) cultivar, we report here on two transformed elite Indica varieties (IR64 and MTL250) plus one Japonica variety Taipei 309. Indica varieties are predominantly consumed in the areas with vitamin A deficiency. To conform with regulatory constraints, we changed the vector backbone, investigated the absence of beyond-border transfer, and relied on Agrobacterium tumefaciens-mediated transformation to obtain defined integration patterns. To avoid an antibiotic selection system, we now rely exclusively on phosphomannose isomerase as the selectable marker. Single integrations were given a preference to minimize potential epigenetic effects in subsequent generations. These novel lines, now in the T3 generation, are highly valuable because they are expected to more readily receive approval for follow-up studies such as nutritional and risk assessments and for breeding approaches leading to locally adapted variety development.