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; Labate, Joanne; DAVIS, ANGELA - Sakata Seed America, Inc; FEI, ZHANGJUN - Cornell University

Submitted to: Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2021
Publication Date: 8/7/2021
Citation: Grumet, R., Mccreight, J.D., Mcgregor, C., Weng, Y., Mazourek, M., Reitsma, K., Labate, J.A., Davis, A., Fei, Z. 2021. Genetic resources and vulnerabilities of major cucurbit crops. Gene. genes12 081222. https://doi.org/10.3390/genes12081222.
DOI: https://doi.org/10.3390/genes12081222

Interpretive Summary: Major economically important cucurbit crops include watermelon, melon, cucumber, and pumpkin/squash. These crops were domesticated in Africa, Asia, and the Americas, respectively, and followed by distribution throughout the world where secondary centers of diversity were formed. Each of these crops is challenged by multiple diseases and 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. We examined crop vulnerabilities in the four major cucurbit crops, their uses, challenges, and genetic resources. Germplasm banks are the primary method to preserve genetic diversity, which 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, large, insect-pollinated outcrossing plants with 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 facilitating collection, preservation, and access to critical cucurbit diversity. This work systematically analyzed achievements and issues in worldwide collections of four major cucurbit crops. The information should be useful for cucurbit breeders, geneticists on use, and conservation of cucurbit germplasm.

Technical Abstract: The Cucurbitaceae family provides numerous important crops including watermelons (Citrullus lanatus) melons (Cucumis melo), cucumbers (Cucumis sativus), and pumpkins and squashes (Cu-curbita 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 di-versity, have been extensively utilized by cucurbit breeders, especially for resistances to biotic and abiotic stresses. Recent genomic efforts have documented genetic diversity, population struc-ture 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, large, insect-pollinated outcrossing plants with 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 facilitating collection, preser-vation, and access to critical Cucurbitaceae diversity.