|McCreight, James - Jim|
|Wintermantel, William - Bill|
|NATWICK, ERIC - University Of California - Cooperative Extension Service|
Submitted to: Cucurbitaceae Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/6/2016
Publication Date: 8/26/2016
Citation: McCreight, J.D., Wintermantel, W.M., Natwick, E.T. 2016. New sources of resistance to CYSDV in melon. In: Kozik, E.U., Paris, H.S., editors. Cucurbitaceae 2016, XIth Eucarpia Meeting on Genetics and Breeding of Cucurbitaceae, July 24-28, 2016, Warsaw, Poland. p. 61–65.
Technical Abstract: Cucurbit yellow stunting disorder virus (CYSDV) is a whitefly-transmitted closterovirus that reduces melon (Cucumis melo L.) fruit yield and quality in greenhouse and open-field production systems in the Middle East, the Mediterranean Basin, the Americas, and Asia. Resistance to CYSDV has been reported in melon accessions, TGR 1551 (PI 482420) and PI 313970, both members of the C. melo ssp. agrestis Acidulus Group. Their non-sweet, vegetable type fruits are similar: small, oval, thin flesh, and extremely hard and bitter at maturity, though slightly aromatic. This poses a challenge to development of sweet, western US shipping type muskmelon (C. melo ssp. melo Group Reticulatus) and green flesh honeydew (C. melo ssp. melo Inodorus Group) cultivars. Neither accession is immune to CYSDV infection. We evaluated, therefore, approximately 500 melon plant introductions from India from 2007 through 2012 in replicated field tests for sources higher-level resistance to CYSDV. Self-pollinated progenies from single putative resistant plants in two accessions tested in 2009 (one accession) and 2010 (one accession) expressed resistance in 2012. Six Indian accessions planted in 2011 were heterogeneous for reactions to CYSDV, and were selected for self-pollination and re-evaluation in 2013 and subsequent years. Most of these putative sources of resistance proved susceptible in subsequent field tests. None provide higher-level resistance than TGR 1551 or PI 313970, based on ELISA estimates of virus titer. Two accessions of note for plant breeders are PI 123496 and PI 145594. PI 123496 produces fruit with many characteristics of sweet melons: medium-large size (1.5 kg), shallow vein tracts, scattered net, round-oval shape, and comparable flesh thickness. PI 145594 fruit are non-sweet, vegetable type, like TGR 1551, but its F1 (Impac x PI 145594) produced large, oval, dark green, lightly netted fruit, and the F2 segregated a high number of sweet melon-like fruit.