ISOLATION OF A NEW PARAMUTAGENIC ALLELE OF THE SULFUREA LOCUS IN THE TOMATO CULTIVAR MONEYMAKER FOLLOWING IN-VITRO CULTURE

A new allele, SC148. of the sulfurea locus in Lycopersicon esculentum was detected in a line derived after repeated selfing of plants that h ad been regenerated from tissue culture. Like the original sulf mutant , SC148 displayed two mutant phenotypes: green-yellow speckled plants in which the sulf(vag) allele is present and pure yellow plants homozy gous for the sulf(pura) allele. Although the mutant alleles are recess ive to wild-type, an unpredictable number of variegated and pura plant s appeared in F1 progenies that had been derived from crosses between SC148 and wild-type tomato plants. The presence of the wild-type sulf allele in these variegated heterozygotes was demonstrated using a cyt ological marker that is linked to sulf. It is concluded that the mutan t sulf allele of SC148, imposes its variegated expression state on the wild-type sulf+ allele present in sulf+/sulf(vag) heterozygotes. This behaviour, known as paramutation, has also been described for the ori ginal sulf allele. The SC148 allele, however, seems to induce changes at an earlier stage in development. The analogy of this paramutagenic system to dominant position effect variegation in Drosophila is discus sed.