Quantitative trait loci (QTL) mapping of important traits in watermelon

Summary

Watermelon is one of the most important vegetable crops in Georgia, but is lacking in molecular tools to aid breeding efforts. We developed genomic tools that will enable watermelon breeders to use marker assisted selection (MAS) to accelerate cultivar development. Our efforts resulted in the identification of the chromosomal regions associated with fruit, seed and flower traits, as well as Papaya ringspot virus (PRSV-W) resistance. We also developed mapping populations segregating for resistance to Gummy Stem Blight and Fusarium wilt, and these traits will be the next targets for MAS

Situation

Watermelon is consistently ranked as one of the most important vegetable crops in Georgia with a 2011 farm gate value of ~$98 million. Despite its importance watermelon is sadly lacking in genomic tools that would expedite watermelon breeding for horticultural traits and disease resistance.

Response

Our aim was to identify Quantitative Trait Loci (QTL) associated with important horticultural traits in watermelon. The markers associated with such QTL can potentially be used for Marker Assisted Selection (MAS) in watermelon breeding. We previously developed the first single-nucleotide polymorphism (SNP) maps and we now used these resources to find QTL associated with sex expression, time to flowering and resistance to PRSV-W. We also developed mapping populations that will be used in future to find chromosomal regions associated with resistance to Gummy Stem Blight and Fusarium wilt race 2, important diseases in Georgia.

Impact

A number of QTL were identified for flower sex expression and time to flowering, including a major QTL that were stable across years. Flowering time is an important trait affecting synchronization of flowering in triploid cultivars and diploid pollenizers. The SNP markers associated with these traits will be useful for breeding efforts. A functional SNP marker was identified for resistance to PRSV-W and this marker is already being used for selection in our breeding program. Resistance to Gummy Stem Blight and Fusarium wilt race 2 are our next targets for MAS and to this end we developed populations segregating for these traits. Our research lays the foundation for MAS in watermelon as well as future efforts to accelerate breeding for traits of special importance to Georgia watermelon growers such as synchronized flowering and disease resistance.

State Issue

Agricultural Profitability and Sustainability

Details

• Year: 2013
• Geographic Scope: Multi-State/Regional
• County: Clarke
• Program Areas:
  • Agriculture & Natural Resources