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Abstract

Manipulation of agronomic traits at the cellular and molecular levels offers an efficient approach to enhance conventional breeding efforts for rice improvement. Plant regeneration protocols, required for biotechnological applications, have not yet been developed for a number of important rice cultivars. This study was conducted to establish a system for plant regeneration of elite rice cultivars adapted to the southern U.S.A. Callus was induced from dehusked grains of cultivars Alan, Katy, and LaGrue, on MS media containing 0.5, 2, and 4 mg L-1 2,4-D, with 0.5 mg L-1 kinetin or without kinetin. Plant regeneration was accomplished by transferring the callus to a hormone-free medium. Callus proliferation was influenced by 2,4-D, kinetin, and genotype in two-way interactions. The effects of these factors on embryogenesis and rhizogenesis was expressed in a three-way interaction. Depending upon the genotype up to 50% plant regeneration was obtained. In most cases treatments consisting of 0.5 to 2 mg L-1 2,4-D plus 0.5 mg L-1 kinetin produced the best callus proliferations with the highest embryogenic capacity. Regenerants grew to maturity in soil and produced viable seeds. The establishment of this regeneration system is essential for the development of a genetic transformation system for the aforementioned commercial rice cultivars.

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