The 2011 ASHS Annual Conference

Honeydew, an inodorus class of muskmelon, has both important nutritional and commercial values in the market. Green-fleshed honeydew with non-netted smooth rind not only provides a good source of vitamin C, folate and potassium, but may also reduce a potential food safety issue concerning bacterial contamination in the netted rind muskmelons.  Our project goal is to enhance honeydew’s nutritional value and flavor. Genetic transformation is a useful tool to assist traditional plant breeding in order to integrate novel genes within and across species. A reliable and highly efficiency plant regeneration system is the foundation of transformation. However, limited regeneration research has been reported for honeydew melons, and no transformation research has been reported. Our research focus has been to develop a successful regeneration and Agrobacterium tumefaciens-mediated transformation system using our elite honeydew line, ‘150’. Therefore, we were to develop a highly efficient shoot regeneration system using different plant growth regulators in this study and to examine ploidy variation which is a common problem resulted from tissue culture. Four combinations of plant growth regulator treatments using BA, ABA and IAA were tested on shoot regeneration from cotyledonary explants. MS basal medium supplemented with BA 1 mg·l^-1 and ABA 0.26 mg·l^-1 appeared to be the best in terms of highest shoot regeneration frequency and lowest curvature tendency. Overall, 50 to 60 percent of regenerated plants were identified as polyploid (tetraploid or mixoploid) based on flow cytometry analysis. The morphological characteristics of leaves, flowers, fruits and seeds of the polyploid regenerants were compared with diploid plants. So far, no significant difference has been identified in polyploid honeydew plants with respect to plant and fruit morphology. This research is supported by USDA-CSREES Special Grant “Designing Foods for Health” 2009-34402-19831.