|Wang, Congli - UNIVERSITY OF CALIFORNIA|
|Duong, Tra - UNIVERSITY OF CALIFORNIA|
|Robert, Phillip - UNIVERSITY OF CALIFORNIA|
Submitted to: Journal of Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2017
Publication Date: 6/10/2018
Citation: Wang, C., Ulloa, M., Duong, T., Robert, P. 2018. Quantitative trait loci mapping of multiple independent loci for resistance to fusarium oxysporum f. sp. vasinfectum races 1 and 4 in an interspecific cotton population. Journal of Phytopathology. 108:759-767.
Interpretive Summary: The soil-borne fungal pathogen Fusarium oxysporum f. sp. vasinfectum (FOV), caused one of the most devastating vascular diseases in many cash crops, especially in cotton. Fusarium types represent expanding threats to cotton production in the U.S. and in other countries of the world. Resistant cultivars are highly effective in preventing crop loss from FOV infection. Progeny and breeding lines developed between Pima and Upland cottons were used to identify molecular markers associated with FOV and resistance. Analyses from this research validated the importance of previously reported markers and chromosome regions and added new information for the location of FOV resistance genes. Some of the breeding lines showed resistance to both fusarium wilt types, providing multiple resistance sources for breeding. In addition, these new trait-linked markers provide a valuable resource for marker assisted selection or MAS of FOV resistance during the breeding process.
Technical Abstract: Fusarium wilt, caused by the soil-borne fungal pathogen Fusarium oxysporum f. sp. vasinfectum (FOV), is a vascular disease of cotton (Gossypium spp.). FOV race 1 (FOV1) causes major plant injury and yield loss in G. hirsutum cultivars with co-infection with root-knot nematode (Meloidogyne incognita), while FOV race 4 (FOV4) causes plant damage in most G. barbadense cultivars without nematode co-infection. QTL analysis of the interspecific cross G. barbadense Pima S-7 × G. hirsutum Acala NemX revealed separate multiple loci determining resistance to FOV1 and FOV4, confirming that race specificity occurs in F. oxysporum f. sp. vasinfectum. Six major QTLs were identified on chromosomes 12, 21, 1, 2, 15 for FOV1 resistance and four major QTLs on chromosomes 8, 14, 16 and 17 for FOV4 resistance based on disease index. Of these QTLs, a major QTL in Pima S-7 linked to SSR marker HAU1434-329/300 on chromosome (Chr) 12 contributed 16-11 % to FOV1 resistance from 10 days to 23 days after inoculation based on disease index. One major locus with additive effect on Chr 17 from Acala NemX allele was identified close to two SSR markers (BNL2650-0/196, CIR112-0/226), which accounted for 16% and 26% of resistance response to FOV4 at 10 and 13 DAI, respectively, increasing to 35-36% at 16, 20, and 23 DAI. Interestingly, the region on Chr 14 homoeologous with Chr 17 accounted for 9-11% of resistance response to FOV4. Minor QTLs contributing to resistance to both FOV1 and FOV4 also were identified in different stages after inoculation. Both parents contributed resistance to FOV1 and FOV4. This research validates the importance of previously reported markers and chromosome regions and adds new information for the location of FOV resistance genes. In addition, these new trait-linked markers provide a valuable resource for marker-assisted selection of FOV resistance. Some of the F8 RI lines have resistance to both Fusarium wilt races 1 and 4 and also to root-knot nematode, providing multiple resistance sources for breeding.