Project Number: 6659-21000-017-00
Project Type: Appropriated

Start Date: May 19, 2008
End Date: May 18, 2013

Objective:
Determine the genetic control of resistance to root-knot nematode (Meloidogyne incognita) and Fusarium wilt (Fon race 2) in watermelon, identify and map DNA-based markers closely linked to identified resistance loci, and release resistant watermelon lines. Utilize genomic tools to develop genetic linkage maps for watermelon and diagnostic DNA-based markers for host-plant resistance to viruses and key watermelon fruit traits. Develop inbred broccoli lines with tolerance to high temperature stress and elucidate the underlying genetic control of the tolerance. Breed high yielding, self-compatible inbred broccoli lines with high productivity and high levels of health-promoting compounds. Elucidate the genetic control of bacterial leaf spot resistance in leafy green Brassicas (B. juncea and B. rapa) and release resistant breeding lines resulting from the research.

Approach:
Select parental lines of watermelon, broccoli, or leafy green brasscias based on phenotypic expression of resistance, tolerance, or quality traits under study. Use the selected parents to construct conventional (i.e., F2, BC1, recombinant inbred) and doubled haploid (for broccoli only) populations that segregate for the traits of interest, and then employ those populations in studies to determine mode of inheritance of each character. Utilize PCR-based markers and other genomic technologies to identify sequences linked to the studied characters and to locate controlling genes on linkage maps. Use particular markers (i.e., SSR, SRAP, SNPs, or SCARs) closely associated with traits of interest to develop tools for marker-assisted selection. Based on knowledge gained through above studies, devise breeding strategies, and applications of marker technologies to use in the further development of horticulturally enhanced lines or hybrids that express resistances and other traits of interest and that also produce high quality vegetables. Make enhanced lines available through public releases or commercial licensing. Continue ongoing searches for new resistances and tolerances among watermelon and vegetable Brassica accessions for the U.S. PI and other collections.