Variation for genetic recombination among tomato plants regenerated from three tissue culture systems

Abstract

Shoot morphogenesis was compared among two tomato inbred lines, two mutant lines, and their eight reciprocal F1 hybrids in three tissue culture systems. The number of shoots per explant was greatest on tomato pedicel explants, intermediate on cotyledon calli, and poor on micropropagated shoot tips. Genetic recombination rates of F1 hybrid plants regenerated from three tissue culture systems were analyzed by backcrossing the regenerated plants with mutant parents and comparing the observed crossover frequencies with those expected based on control plants raised from seed. Increased recombination rates and map distance were observed among plants from micropropagated shoot tips (18.8%), cotyledon calli (17.3%), and pedicel explants (13.5%) between the markers sunny (sy) and baby leaf syndrome (bls), which flank the centromere on chromosome 3. Conversely, decreased recombination rates and map distance were observed between bls and the locus solanifolia (sf), which is more distal to the centromere on the same arm of chromosome 3 as bls. Increased recombination rates and map distance among plants from micropropagated shoot tips, cotyledon calli, and pedicel explants were also observed between the loci white virescence (wv) and anthocyanin reduced (are) on chromosome 2.Key words: genetic recombination, tomato, Lycopersicon esculentum, pedicel explants, micropropagation, callus culture, plant regeneration.