Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2006
Publication Date: 9/20/2006
Citation: Chen, J., Ren, G., Luo, X., Staub, J.E., Jahn, M. 2006. Inheritance of aspartate aminotransferase (AAT) in cucumis species as revealed by interspecific hybridization. Canadian Journal of Botany. 84:1503-1507. Interpretive Summary: Aspartate aminotransferase (AAT) is an enzyme that is required for critical cellular reactions leading to the breakdown and elimination of waste products from plant cells. Because of the significance of this enzyme in plant metabolism, it has received considerable scientific attention. This enzyme has several chemical forms (isozymes) in plants. These isozymes are controlled by genes (hereditary units). Genes are arranged in a linear array and these linear arrays are called chromosomes. The locations of genes that control the function (whether enzymes are active or not) of such enzymes as AAT have been located on chromosomes (the position on the linear array) to allow for their manipulation using biotechnology (genetic tools that allow for dissection of gene function). The genetics of AAT in cucumber has not been clarified, and therefore a study was designed using biotechnological tools to identify genes that control AAT. It was determined that two genes interact with each other in the cell to control AAT in cucumber. This information is important to plant breeders who want to manipulate the genes for AAT in order to develop plants with improved enzyme characteristics. The results of this experiment will be useful to the grower as new cultivars are developed with improved metabolic (cellular) activity to increase productivity and allow them to become more globally competitive.
Technical Abstract: The inheritance of aspartate aminotransferase (AAT) isozymes was investigated in Cucumis sativus L. (CC; 2n = 2x = 14), C. 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. C. 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). C. hytivus, a synthetic species derived from doubling the chromosome number of a F1 from a C. sativus x 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 BC1 progenies that are similar in morphology. Aat–3 was monomorphic in this mating, encoding a single allele Aat-3 (1).