Inheritance of aspartate aminotransferase (AAT) inCucumisspecies as revealed by interspecific hybridization

Abstract

The inheritance of aspartate aminotransferase (AAT) isozymes was investigated in Cucumis sativus L. (CC; 2n = 2x = 14), Cucumis hystrix Chakr. (HH; 2n = 2x = 24), the synthetic amphidiploid species C. hytivus Chen & Kirkbride (HHCC; 2n = 4x = 38), and the allotriploid (HCC; 2n = 3x = 26) from backcrossing C. hytivus to C. sativus. Two polymorphic loci, Aat-1 and Aat-2, and one monomorphic locus, Aat-3, were detected among these parents and their progenies by using polyacrylamide gel electrophoresis. Cucumis sativus displayed the fast-migrating anodic band for Aat-1 (2), while C. hystrix contained a slow-migrating cathodic band (1). For Aat-2, the slow-migrating cathodic band was observed with C. sativus (1), whereas C. hystrix contained the fast-migrating anodic band (2). Cucumis hytivus, a synthetic species derived from doubling the chromosome number of a F1from a C. sativus × C. hystrix mating, exhibited the typical hybrid dimeric banding pattern resulting from the combination of two parental homomeric products with equal staining intensity and a heteromeric product with intermediate mobility and greater staining intensity than either homomeric product. The difference in band intensity between C. hytivus and its backcross progenies, when C. sativus was the recurrent parent, were due to the dosage effects of alleles at Aat-1 and Aat-2. These banding morphotypes can be used for typing of C. hytivus and BC1progenies that are similar in morphology. Aat-3 was monomorphic in this mating, encoding a single allele Aat-3 (1).