The Cucurbitaceae 2022 conference was held in Naples, Florida on October 30 – November 2. The conference was organized by CucCAP co-PIs Geoffrey Meru from the University of Florida and Cecilia McGregor from the University of Georgia. Researchers and industry representatives from North America, Europe and Asia shared information about cucurbit genomics, breeding, disease resistance and cultivation. CucCAP researchers presented 28 talks and posters.
Downy mildew (DM) is an important disease of cucumber and other cucurbits. Many quantitative trait loci (QTL) have been identified from different resistant resources but very few have been fine mapped or cloned. CucCAP researchers in USDA-ARS and the University of Wisconsin Madison reported identification and functional characterization of the candidate gene for the major-effect QTL, dm5.3, for DM resistance from the plant introduction line PI 197088. This gene, which can enhance plant disease signaling, is currently being used to breed for disease resistance in cucumber.
Papaya ringspot virus-W (PRSV-W) causes severe yield losses in squash production. The Meru laboratory at the University of Florida identified a single QTL for resistance on Chromosome 09 of the C. moschata genome. Subsequent testing identified two SNP markers as potential targets for marker-assisted selection. The findings of this study will facilitate breeding for resistance against PRSV-W in commercial squash cultivars.
Resistance to fungicides is a concern with cucumber downy mildew, Pseudoperonospora cubensis clade 2. These fungicides still suppressed downy mildew well enough that yields of marketable-sized fruit of a susceptible slicing cucumber were much better than not spraying.
Cucurbit downy mildew (CDM), is an economically significant disease of cucurbitaceous crops in the Eastern United States (US). Cucumbers are particularly susceptible and as a result, disease management of this pathogen relies heavily on fungicide use.
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.
Stated preference surveys are a relatively new approach to measuring specialty crop producers’ valuation of breeding traits.
Powdery mildew is one of the most important diseases of melon. CucCAP researchers used a densely genotyped melon population to identify QTL associated with resistance in multiple plant tissues.