Germplasm collections maintained by the US National Plant Germplasm System and those of other countries are critical sources of diversity utilized by breeders for crop improvement. This review summarizes status of collections and vulnerabilities for cucurbit crops.
This pHD candidate’s CucCAP grant research focused on developing squash breeding lines with some Phytophthora blight resistance and mapping genes involved in disease resistance. His other focus was pathogen population genetics. In CucCAP1 the squash team sequenced and characterized isolates of the causal agent, Phytophthora capsici, from around New York and mapped genes in the pathogen associated with mating type, fungicide resistance, and virulence.
Luis Rivera-Burgos worked on breeding watermelon for gummy stem blight resistance with Dr. Todd Wehner on the first CucCAP project. Their research focused on the evaluation of resistance to Gummy Stem Blight in a population of recombinant inbred lines of watermelon x Citron.
Clemson research shows cultivar selection critical for managing fusarium wilt in watermelon.
The U.S. National Plant Germplasm System maintains a melon germplasm collection from worldwide melon production areas and regions where primitive melons exist. The CucCAP team genetically characterized the collection to increase understanding of genetic diversity, phylogenetic relationships, and population structure of the collection, and to improve melon taxonomic classifications. A core collection was developed from the analysis to provide a public resource for future research and genomics-assisted breeding. Thirty-five morphological characters were evaluated in the core collection to identify genomic regions potentially related to fruit quality and other horticultural traits important in melon improvement.
Feifan Chan’s work in Yiqun Weng’s lab focuses on on pathogen resistance to downy mildew and powdery mildew in cucumber.
Downy mildew caused by Pseudoperonospora cubensis is the most destructive foliar disease affecting cucurbit crops. Genomic studies by Dr. Lina Quesada-Ocampo and colleagues at North Carolina State University showed that different isolates preferentially infect different cucurbit crops. From this information, a multiplex PCR-based assay was combined with spore trapping to identify which crops are most at risk. These results can facilitate timely and crop-specific fungicide application prior to appearance of symptoms in sentinel plots.
Matthew is evaluating fungicide sensitivity of CDM to single fungicide products and efficacy of forecasters in controlling CDM and spore trapping of P. cubensis using impaction spore traps.