Discovery of a major QTL for resistance to the guava root-knot nematode (Meloidogyne enterolobii) in ‘Tanzania’, an African landrace sweetpotato (Ipomoea batatas)

Authors: FRAHER, SIMON - North Carolina State University; SCHWARZ, TANNER - North Carolina State University; HEIM, CHRIS - North Carolina State University; DE SIQUEIRA GESTEIRA, GABRIEL - North Carolina State University; MOLLINARI, MARCELO - North Carolina State University; DA SILVA PEREIRA, GUILHERME - Universidade Federal De Vicosa; ZENG, ZHAO-BANG - North Carolina State University; Brown-Guedira, Gina; GORNY, ADRIENNE - North Carolina State University; YENCHO, G. CRAIG - North Carolina State University

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2024
Publication Date: 9/26/2024
Citation: Fraher, S., Schwarz, T., Heim, C., De Siqueira Gesteira, G., Mollinari, M., Da Silva Pereira, G., Zeng, Z., Brown Guedira, G.L., Gorny, A., Yencho, G. 2024. Discovery of a major QTL for resistance to the guava root-knot nematode (Meloidogyne enterolobii) in ‘Tanzania’, an African landrace sweetpotato (Ipomoea batatas). Theoretical and Applied Genetics. 137:234. https://doi.org/10.1007/s00122-024-04739-1.
DOI: https://doi.org/10.1007/s00122-024-04739-1

Interpretive Summary: Sweetpotato is among the world’s most important food crops and is North Carolina’s most important vegetable crop. The recent introduction of Guava root-kot nematode poses a significant economic threat to NC’s sweetpotato industry and breeding resistance into new varieties has become a high priority. In this study, we used a population of lines developed from a cross between the susceptible variety Beauregard and a resistant African landrace Tanzania to genetically characterize the resistance in Tanzania. We identified DNA markers linked to a gene conferring resistance to Guava root-knot nematodes that have potential for marker assisted selection for accelerate development of improved sweetpotato varieties.

Technical Abstract: Sweetpotato, Ipomoea batatas (L.) Lam. (2n'='6x'='90), is among the world’s most important food crops and is North Carolina’s most important vegetable crop. The recent introduction of Meloidogyne enterolobii poses a significant economic threat to North Carolina’s sweetpotato industry and breeding resistance into new varieties has become a high priority for the US sweetpotato industry. Previous studies have shown that ‘Tanzania’, a released African landrace, is resistant to M. enterolobii. We screened the biparental sweetpotato mapping population, ‘Tanzania’ x ‘Beauregard’, for resistance to M. enterolobii by inoculating 246 full-sibs with 10,000 eggs each under greenhouse conditions. ‘Tanzania’, the female parent, was highly resistant, while ‘Beauregard’ was highly susceptible. Our bioassays exhibited strong skewing toward resistance for three measures of resistance: reproductive factor, eggs per gram of root tissue, and root gall severity ratings. A 1:1 segregation for resistance suggested a major gene conferred M. enterolobii resistance. Using a random-effect multiple interval mapping model, we identified a single major QTL, herein designated as qIbMe-4.1, on linkage group 4 that explained 70% of variation in resistance to M. enterolobii. This study provides a new understanding of the genetic basis of M. enterolobii resistance in sweetpotato and represents a major step towards the identification of selectable markers for nematode resistance breeding.