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Title: Characterizing and mapping resistance in synthetic-derived wheat to Rhizoctonia root rot in a green bridge environment

item MAHONEY, AARON - Washington State University
item BABIKER, EBRAHIEM - Washington State University
item Paulitz, Timothy
item See, Deven
item Okubara, Patricia
item HULBERT, SCOT - Washington State University

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2016
Publication Date: 10/15/2016
Citation: Mahoney, A., Babiker, E., Paulitz, T.C., See, D.R., Okubara, P.A., Hulbert, S. 2016. Characterizing and mapping resistance in synthetic-derived wheat to Rhizoctonia root rot in a green bridge environment. Phytopathology. 106:1170-1176.

Interpretive Summary: Genetics resistance to soilborne fungal pathogens is lacking in the small grain cereals, including wheat. Such resistance will provide cereal growers in the Pacific Northwest and elsewhere with an option to adopt non-till or direct seed, which conserves soil and soil moisture. Six new genotypes having improved disease resistance have been discovered in a collection of wheat lines from Mexico. One line in particular exhibited good and consistent tolerance in the field and in the greenhouse. Three genes appear to control the resistance.

Technical Abstract: Root rot caused by Rhizoctonia species is an economically important soilborne disease of spring planted wheat in growing regions of the Pacific Northwest (PNW). The main method of controlling the disease currently is through tillage, which deters farmers from adopting the benefits of minimal tillage. Genetic resistance to this disease would provide an economic and environmentally sustainable resource for farmers. In this study, a collection of synthetic-derived genotypes were screened in high inoculum, and low inoculum field environments. Six genotypes were found to have varying levels of resistance and tolerance to Rhizoctonia root rot. One of the lines, SPBC-3104 (‘Vorobey’), exhibited good tolerance in the field and was crossed to a susceptible PNW adapted cultivar ‘Louise’ to examine the inheritance of the trait. A population of 190 BC1-derived recombinant inbred lines were assessed in two field green bridge environments and in soils artificially infested with R. solani AG8. Genotyping-by-sequencing and composite interval mapping identified three quantitative trait loci (QTL) controlling tolerance. Beneficial alleles of all three QTL were contributed by the synthetic-22 derived genotype SPCB-3104.