|Bowden, Robert - Bob|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2007
Publication Date: 10/19/2007
Citation: Sukwinder-Singh, Sharma, I., Bains, N.S., Seghal, S.K., Bowden, R.L. 2007. Molecular mapping of QTLs for Karnal bunt resistance in two recombinant inbred populations of bread wheat. Theoretical and Applied Genetics (2007) 116:147-154. Interpretive Summary: Karnal bunt (KB) of wheat, caused by the fungus Tilletia indica, is a challenge to the grain industry, owing not to direct yield loss but to quarantine regulations that may restrict international movement of affected grain. Several different sources of resistance to KB have been reported. Understanding the genetics of resistance will facilitate the introgression of resistance into new wheat cultivars. The objectives of this study were to identify quantitative trait loci (QTLs) associated with KB resistance and to identify DNA markers in two recombinant inbred line populations derived from crosses of the susceptible cultivar WH542 with resistant lines HD29 and W485. Populations were evaluated for resistance against the KB pathogen for three years at Punjab Agricultural University, Ludhiana, India. Two new QTLs (Qkb.ksu-5BL.1 and Qkb.ksu-6BS.1) with resistance alleles from HD29 were identified and mapped in the intervals Xgdm116–Xwmc235 on chromosome 5B (deletion bin 5BL9-0.76-0.79) and Xwmc105–Xgwm88 on chromosome 6B (C-6BS5-0.76). They explained up to 19 and 13% of phenotypic variance, respectively. Another QTL (Qkb.ksu-4BL.1) with a resistance allele from W485 mapped in the interval Xgwm6–Xwmc349 on chromosome 4B (4BL5-0.86-1.00) and explained up to 15% of phenotypic variance. Qkb.ksu-6BS.1 showed pair-wise interactions with loci on chromosomes 3B and 6A. Markers suitable for marker-assisted selection are available for all three QTLs.
Technical Abstract: Quantitative trait loci (QTLs) associated with resistance to Karnal bunt (Tilletia indica) were identified in two bread wheat recombinant inbred mapping populations derived from the crosses of WH542/HD29 (population-1) and WH542/W485 (population-2). These populations were evaluated for reaction to T. indica in five seasons at Punjab Agricultural University, Ludhiana, India. Incidence of kernel infection ranged from 0 to 5 percent on resistant (HD29, W485) and 25 to 71 percent on susceptible (WH542) parents. Single marker analysis and interval mapping were used to identify the genomic regions having consistent influence on the disease reaction. QTLs for KB resistance were identified in population-1 on chromosomes 4B (R2 = 8 to 12 %), 5B (R2 = 7 to 21 %) and 6B (R2 = 6 to 21 %); and in population-2 on chromosomes 4B (R2= 6 to 16 %) and 6A (R2 = 7 to 22 %). QTLs for the resistance on chromosomes 4B, 5B and 6B were tagged with flanking PCR-based markers and these can be used for marker-assisted selection.