Validation of multiple disease resistance QTL from chromosome segment substitution population in F2:3 family populations

Authors: MARTIN, LAIS - North Carolina State University; RUCKER, ELIZABETH - Virginia Polytechnic Institution & State University; THOMASON, WADE - Virginia Polytechnic Institution & State University; Holland, Jim - Jim; WISSER, RANDALL - University Of Delaware; Balint-Kurti, Peter

Submitted to: G3, Genes/Genomes/Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2019
Publication Date: 8/1/2019
Citation: Martin, L., Rucker, E., Thomason, W., Holland, J.B., Wisser, R., Balint Kurti, P.J. 2019. Validation of multiple disease resistance QTL from chromosome segment substitution population in F2:3 family populations. G3, Genes/Genomes/Genetics. 9:2905-2912.

Interpretive Summary: Previously identified loci associated with maize disease resistance were tested in new, independent populations. Of 44 loci tested 16 were validated.

Technical Abstract: Southern Leaf Blight, Northern Leaf Blight, and Gray Leaf Spot, caused by ascomycete fungi, are among the most important foliar diseases of maize worldwide. Previously, disease resistance quantitative trait loci (QTL) for all three diseases were identified in a connected set of chromosome segment substitution line (CSSL) populations designed for the identification of disease resistance QTL (Lopez-Zuniga et al. 2019). Some QTL for different diseases co-localized, indicating the presence of multiple disease resistance (MDR) QTL. The goal of this study was to perform an independent test of several of the MDR QTL identified to confirm their existence, study allele dominance effects and derive a more precise estimate of allele additive and dominance effects. Twelve F2:3 populations were made from crosses between individual CSSLs that showed strong resistance across the three diseases and their more susceptible recurrent parent, H100. The resulting populations were assessed for each of the three diseases in replicated trials and genotyped with markers previously associated with disease resistance. Pairwise phenotypic correlations across all the populations for resistance to the three diseases ranged from 0.2 to 0.3 and were all significant at the alpha level of 0.01. Of the 44 QTL tested, 16 were validated (identified at the same genomic location for the same disease or diseases) and several novel QTL/disease associations were found. Two MDR QTLs were associated with resistance to all three diseases. This study identifies several potentially important MDR QTL and demonstrates the importance of independently evaluating QTL effects following their initial identification.