Interactions of genotype and plant growth regulators affecting direct shoot regeneration of lettuce (Lactuca sativa L.)

Abstract

Lettuce (Lactuca sativa L.) is one of the most important vegetable crops. The chloroplast transformation of lettuce requires a reproducible method to regenerate shoots directly from leafy explants. The direct shoot regeneration in lettuce is highly depends on genotype and the combinations of plant growth regulators. Callus induction, average number of regenerated shoots per leafy explant and percentage of shoot-producing explants were studied by investigating the effects of genotype and different concentrations of NAA and BAP. Orumia and American genotypes in media containing 0.1 mg l -1 NAA with either 0.1 mg l -1 or 0.2 mg l -1 BAP produced the highest number of regenerated shoots per explant. In addition, the minimum callus formation was observed in the same media from Ahwazi and Orumia genotypes. The results showed low callus formation and increased direct shoot regeneration from lettuce explants in low concentrations of NAA and BAP. The callus induction and direct shoot regeneration from leaf explants were correlated significantly and negatively. These data recommend a protocol for direct shoot regeneration in producing transplastomic lettuce.