Fertile Transgenic Rice Plants Generated via Protoplasts from the U.S. Cultivar Labelle

Abstract

Toward a long‐term goal of applying gene transfer technology to enhance rice ( Oryza sativa L.) breeding programs in the USA, we initiated a concerted effort to establish a transformation system for the long‐grain commercial cultivar Labelle. Embryogenic protoplasts were isolated from immature panicle‐derived suspension cultures. A hygromycin resistance gene was introduced into protoplasts by treatment with polyethylene glycol. Up to 6% of the colonies showed hygromycin resistance after 3 wk selection in the presence of 190 µ M hygromycin B. Plantlets were regenerated from ≈30% of the resistant calli. All six transgenic Labelle plants that were grown to maturity set viable seeds. Southern blot hybridization and progeny segregation analysis demonstrated that hygromycin resistance genes were integrated into the rice genome and inherited as a single locus or closely‐linked loci. We now have a successful procedure to introduce important agronomic traits from other organisms into U.S. long‐grain rice cultivars.