Cucurbit fruits come in different shapes and sizes, controlled by genes underlying cell size and number. In a recent study, a team at West Virginia State University (WVSU) identified genetic factors underlying the giant fruit size of the mammoth group of Cucurbita maxima. The study elucidated genome diversity and identified single nucleotide polymorphism (SNP) markers associated with genes controlling fruit size. In addition to the genomic toolkit useful for breeding programs aiming at pumpkin fruit traits, this study provides insight into population differentiation and evolutionary origins of rare variants contributing to the giant fruit size of certain pumpkin varieties.
Watermelon crops are increasingly threatened by infection by cucurbit downy mildew. While there are limited sources of disease resistance within cultivated watermelon, Citrullus amarus can be a valuable source of resistances. CucCAP scientists performed disease resistance screening and whole genome resequencing of 122 C. amarus accessions. Genome wide association analysis of these materials identified several marker-trait associations and candidate genes, providing potential resources for genomics-assisted breeding for resistance to CDM in watermelon.
Before her current position as a Genetic Purity Lab Manager in the Quality Assurance Department at Sakata Seed America, Inc., in Salinas California, Bidisha Chanda worked for the USDA and conducted research for the CucCAP watermelon team at the US Vegetable Laboratory in Charleston, South Carolina.
Watermelon production in the U.S. and around the world faces serious threats by viral diseases, including aphid-transmitted potyviruses: papaya ringspot virus (PRSV) and zucchini yellow mosaic virus (ZYMV). In a recent study, a CucCAP team examined expression of anti-microbial/anti-viral, ribosome-inactivating proteins (RIPs) in watermelons in response to inoculation with PRSV. The PRSV-resistant citron watermelon (Citrullus amarus) exhibited high RIP expression, versus low expression in plants of the susceptible, cultivated “Charleston Gray” watermelon. This finding may offer additional genetic and genomic resources for improving potyvirus-resistance in watermelon cultivars.
Members of the cucurbit breeding, genetics, and genomics research community are encouraged to submit reports for the 2021 -2022, Cucurbit Genetics Cooperative Report #44. Manuscripts or reports should be submitted to Amnon Levi by February 28th, 2022.
Watermelon Breeding, Genetics, Genomics, Pathology, and Disease Management Publications & Presentations
The watermelon team is led by Amnon Levi. Team objectives are to develop genomic, bioinformatic, mapping approaches and tools for cucurbits, map and develop markers for disease resistance, and introgress, pyramid/stack resistances into advanced breeding lines.
Umesh Reddy and team at WVSU and Amnon Levi and team at USDA, ARS used advance genome sequencing technology to study the effect of genome doubling on gene expression in tetraploid watermelon versus their counterpart diploid watermelon parental plants.