ARS | Publication request: MAIN EFFECTS, EPISTASIS AND ENVIROMENTAL INTERACTIONS OF QTLS FOR FUSARIUM HEAD BLIGHT RESISTANCE IN A RECOMBINANT INBRED POPULATION

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 4, 2006
Publication Date: April 1, 2006
Citation: Ma, H., Bai, G., Zhang, X., Lu, W. 2006. Main effects, epistasis and enviromental interactions of qtls for fusarium head blight resistance in a recombinant inbred population. Phytopathology 96:534-541

Interpretive Summary: Wheat Fusarium head blight (FHB) is an important disease in the U.S.A. Wheat resistance to the disease is conditioned by several genes, each with relatively small effects. An experimental wheat line (CS-SM3-7ADS) with a high level of resistance was developed by replacing the 7A chromosome of wheat cultivar Chinese Spring with the 7A chromosome from resistant cultivar Sumai 3. A mapping population was developed by crossing this line to susceptible cultivar Annong 8455. We constructed a genetic map using 501 molecular markers and identified 10 chromosome regions that were associated with FHB resistance. CS-SM3-7ADS has five resistant regions on chromosomes 2D, 3B, 4D and 6A. One QTL on 3BS had the largest effect on reducing FHB level. Susceptibility genes were detected on chromosomes lA, ID, 4A and 4B. Genes for enhanced FHB resistance were not detected on chromosome 7A of CS-SM3- 7 ADS, therefore the increased FHB resistance in CS-SM3- 7 ADS was not due to any major FHB resistance genes on 7A of Sumai 3. More likely the resistance was due to removal of susceptible allele(s) of gene(s) on 7A of Chinese Spring. Adding FHB enhancing genes or removal of susceptible genes both may significantly enhance wheat resistance to FHB in a wheat cultivar.

Technical Abstract: Chinese Spring-Sumai 3 chromosome 7A disomic substitution line (CS-SM3- 7 ADS) is highly resistant to Fusarium head blight (FHB), and an F7 population of recombinant inbred lines (RILs) derived from the cross CS-SM3-7ADS x Annong 8455 was evaluated for resistance to FHB to investigate main effects, epistasis and environmental interactions of quantitative trait loci (QTLs) for FHB resistance. A molecular linkage map consists of 501 simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers. A total of 10 QTLs were identified with significant main effects on the FHB resistance using MapQTL and QTLMapper software. Among them, CS-SM3- 7 ADS carries FHB-resistance alleles at five QTLs on chromosomes 2D, 3B, 4D and 6A. One QTL on 3BS had the largest effect and explained 30.2% of the phenotypic variance. Susceptible QTLs were detected on chromosomes lA, 1D, 4A and 4B. QTL for enhanced FHB resistance was not detected on chromosome 7A of CS-SM3- 7ADS, therefore the increased FHB resistance in CS-SM3- 7 ADS was not due to any major FHB-resistance QTL on 7A of Sumai 3, but more likely due to removal of susceptible allele(s) of QTL(s) on 7A of Chinese Spring. QTLMapper detected nine pairs of additive-by-additive (AA) interactions at 17 loci that explained 26% phenotypic variance. QTL-by-environment (QE) interactions explained about 49% of phenotypic variation, indicating that the environments significantly affected the expression of the QTLs, especially these epistasis QTLs. Adding FHB enhancing QTLs or removal of susceptible QTLs both may significantly enhance the degree of wheat resistance to FHB in a wheat cultivar.