Genetic resources and vulnerabilities of major cucurbit crops

Authors: GRUMET, REBECCA - Michigan State University; McCreight, James - Jim; MCGREGOR, CECILIA - University Of Georgia; Weng, Yiqun; MAZOUREK, MICHAEL - Cornell University; REITSMA, KATHLEEN - Iowa State University; Jarret, Robert - Bob; Labate, Joanne; DAVIS, ANGELA - Sakata Seed America, Inc; FEI, ZHANGJUN - Cornell University

Submitted to: Genes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2021
Publication Date: 8/7/2021
Citation: Grumet, R., Mccreight, J.D., Mcgregor, C., Weng, Y., Mazourek, M., Reitsma, K., Jarret, R.L., Labate, J.A., Davis, A., Fei, Z. 2021. Genetic resources and vulnerabilities of major cucurbit crops. Genes. https://doi.org/10.3390/genes12081222.
DOI: https://doi.org/10.3390/genes12081222

Interpretive Summary: The cucurbit crops, namely, watermelon, melon, cucumber, pumpkin, and squash are closely related to each other and are widely used as human food, animal feed, and as ornamentals. These crops originated in Africa, Asia, and the Americas. They spread throughout the world where they became adapted to diverse environments and usage types. Each of these crops is susceptible to damage caused by bacterial, viral, and fungal infection, as well as insect pests and environmental stresses. This review article analyzes cucurbit crop vulnerabilities, their uses, challenges, and genetic resources. Genebanks are valued by cucurbit breeders as sources of new diversity for continued crop improvement. DNA sequencing of cucurbit genebank collections has led to an understanding of this diversity to promote its efficient use. Our ability to address cucurbit crop vulnerabilities will require a combination of investment, rational agricultural and conservation policies, and technological advances to facilitate collection, preservation, and access to critically needed genetic diversity.

Technical Abstract: The Cucurbitaceae family provides numerous important crops including watermelons (Citrullus lanatus), melons (Cucumis melo), cucumbers (Cucumis sativus), and pumpkins and squashes (Cucurbita spp.). Centers of domestication in Africa, Asia, and the Americas, were followed by distribution throughout the world and evolution of secondary centers of diversity. Each of these crops is challenged by multiple fungal, oomycete, bacterial and viral diseases as well as insects that vector disease and cause feeding damage. Cultivated varieties are constrained by market demands, necessity for climatic adaptations, domestication bottlenecks, and in most cases, limited capacity for interspecific hybridization, creating narrow genetic bases for crop improvement. This analysis of crop vulnerabilities examines the four major cucurbit crops, their uses, challenges, and genetic resources. Ex situ germplasm banks, the primary strategy to preserve genetic diversity, have been extensively utilized by cucurbit breeders, especially for resistances to biotic and abiotic stresses. Recent genomic efforts have documented genetic diversity, population structure and genetic relationships among accessions within collections. Collection size and accessibility are impacted by historical collections, current ability to collect, and ability to store and maintain collections. The biology of cucurbits, with insect-pollinated, outcrossing plants, and large, spreading vines, pose additional challenges for regeneration and maintenance. Our ability to address ongoing and future cucurbit crop vulnerabilities will require a combination of investment, agricultural and conservation policies, and technological advances to facilitate collection, preservation, and access to critical Cucurbitaceae diversity.