Molecular studies on induction of genetic variation

In this work, factors that prevent or stimulate genetic variation in Sorghum bicolor (L.) were studied for in vitro propagation or variant selection, respectively. Somaclonal variation can be efficiently controlled by shortening the unorganized phase when somaclonal variation was an undesirable phenomenon. It was accomplished under light condition using high level of BAP (1- 4 mg/l) alone or in combination with 0.5 mg/l 2,4-D to promote direct shoot formation. This condition did not abolish the genetic mutation under the influence of long term culture condition due to the formation of adventitious buds and somatic embryos. Consequently, somaclonal variation increased with the increase of the number of subculture, where it was established by subculture of in vitro obtained buds on MS medium supplemented with 4 mg/l BAP and 0.5 mg/l 2,4-D. To decrease the number of subculture, to avoid extensive somaclonal variation, artificial seeds were obtained via encapsulation of in vitro obtained buds and somatic embryos. The isoenzyme pattern of peroxidase, indophenol oxidase, malate dehydrogenase and esterase was investigated during direct and indirect induction of shoot formation.