Somatic crossing-over can induce isozyme variation in somaclones of Cereusperuvianus Mill. (Cactaceae)

Isoesterase variants detected in plants regenerated from callus tissue cult ure of Cereus peruvianus suggest the occurrence of somatic crossing-over as a possible mechanism for inducing somaclonal variation. The observed pheno typic distribution for the Est-1 locus in somaclones showed an excess of ho mozygous Est-1(1/1) accompanied by a lack of heterozygotes. The in vitro pr oliferating activity may have a mitotic recombination-inducing effect on ca llus tissue.