Pseudomonas leaf spot (PLS) is an emerging disease of watermelon in the United States. To date, there are no reported watermelon cultivars with resistance to PLS. Since Citrullus amarus, a relative of cultivated watermelon, has been a valuable source of many disease resistance genes, the USDA plant introduction (PI) collection of C. amarus was screened for resistance to PLS. The accessions were resequenced and data used to perform a genome-wide association study (GWAS). Genetic markers associated with resistance were identified on five chromosomes. Two were found in genes documented to play important roles in resistance to P. syringae in other species. The results will facilitate breeding for resistance to PLS in watermelon.
For further reading:
Genome-Wide Association Study of Resistance to Pseudomonas syringae in the USDA Collection of Citrullus amarus
By: Gabriel Rennberger, Sandra Branham, and William Wechter
Published in Plant Disease on May 2, 2023.