Submitted to: Cucurbit Genetics Cooperative Report
Publication Type: Research Notes
Publication Acceptance Date: December 20, 2003
Publication Date: December 20, 2003
Citation: Paris, M., Staub, J.E., Mccreight, J.D. 2003. Determination of fruit sampling location for quality measurements in melon (Cucumis melo L.). Cucurbit Genetics Cooperative Report. 26:12-17. Technical Abstract: Fruit quality assessment and characterization is an important objective in many melon improvement programs. There are several simply inherited genes that control melon fruit ripening, shape and flesh color. Examples of such fruit quality genes are flesh color, fruit abscission, spots on the rind, placenta number, mealy flesh, sour taste, empty cavity, seed color, and sutures on the rind. Our laboratories have been interested in collaborative mapping of yield components in a cross between a line designated as USDA 846 and 'Top Mark'. USDA 846 was derived from mating between an exotic accession obtained from Costa Rica and 'Top Mark'. Subsequent backcrossing (BC2 to 'Top Mark') and selfing (S4) of progeny from this initial mating were selected for fruit size and number, multiple lateral branching, and early crown-setting ability and self-pollinated to produce USDA 846. The fruit of line USDA 846 does not fit into a defined market class, having unique epidermal and mesocarp fruit characteristics. We are interested in improving the fruit quality of lines derived from USDA 846, and thus are developing strategies to evaluate specific fruit characteristics for selection and genetic mapping. Therefore, we designed experiments to assess different fruit sampling locations for the determination of fruit firmness and total sugar in commercial hybrids, experimental lines, and a hybrid between USDA 846 and 'Top Mark' in two growing locations (Wisconsin and California). Our results indicate that fruit firmness may be a trait that, when measured under replication, could provide information for inheritance and genetic mapping studies. The precise estimation of total fruit sugar concentration is difficult, i.e., highly variable, and placement of this trait on a genetic map will likely require the measurement of fruit having similar maturity (half- or full-slip) and the examination of several fruit, perhaps as many as 10, from a replication. Studies of inheritance will likely require relatively high replication (perhaps 6) and multiple measurements of plants within a plot (perhaps 5-10). Further methodological development will result in more accurate mapping of fruit quality traits which will increase the effectiveness and efficiency of public and private plant breeders resulting in more rapid development of melon cultivars.