Abstract
BackgroundStripe rust, leaf rust, tan spot, and Karnal bunt are economically significant diseases impacting wheat production. The objectives of this study were to identify quantitative trait loci for resistance to these diseases in a recombinant inbred line (RIL) from a cross HD29/WH542, and to evaluate the evidence for the presence loci on chromosome region conferring multiple disease resistance.Methodology/Principal FindingsThe RIL population was evaluated for four diseases and genotyped with DNA markers. Multi-trait (MT) analysis revealed thirteen QTLs on nine chromosomes, significantly associated with resistance. Phenotypic variation explained by all significant QTLs for KB, TS, Yr, Lr diseases were 57%, 55%, 38% and 22%, respectively. Marginal trait analysis identified the most significant QTLs for resistance to KB on chromosomes 1BS, 2DS, 3BS, 4BL, 5BL, and 5DL. Chromosomes 3AS and 4BL showed significant association with TS resistance. Significant QTLs for Yr resistance were identified on chromosomes 2AS, 4BL and 5BL, while Lr was significant on 6DS. MT analysis revealed that all the QTLs except 3BL significantly reduce KB and was contributed from parent HD29 while all resistant QTLs for TS except on chromosomes 2DS.1, 2DS.2 and 3BL came from WH542. Five resistant QTLs for Yr and six for Lr were contributed from parents WH542 and HD29 respectively. Chromosome region on 4BL showed significant association to KB, TS, and Yr in the population. The multi environment analysis for KB identified three putative QTLs of which two new QTLs, mapped on chromosomes 3BS and 5DL explained 10 and 20% of the phenotypic variation, respectively.Conclusions/SignificanceThis study revealed that MT analysis is an effective tool for detection of multi-trait QTLs for disease resistance. This approach is a more effective and practical than individual QTL mapping analyses. MT analysis identified RILs that combine resistance to multiple diseases from parents WH542 and/or HD29.
Highlights
Among biotic stresses, stripe rust (Yr) (Puccinia striiformis f. sp. tritici), leaf rust (Lr) (P. triticina), tan spot (TS) (Pyrenophora triticirepentis), and Karnal bunt (KB) (Tilletia indica) are important diseases that adversely affect yield and quality of bread wheat (Triticum aestivum L.) throughout the world
We present the results obtained in the last strategy, within a mixture model framework, because they allow to draw the marginal and the joint likelihood profile together, as well as to obtain the estimates of additive and proportion of phenotypic variance explained by each quantitative trait locus (QTL) in each environment
The recombinant inbred line (RIL) population HD29/WH542 was analyzed for quantitative resistance for four different pathogens: P. striiformis f.sp. tritici (Yr), P. triticina (Lr), P. tritici-repentis (TS), and T. indica (KB)
Summary
Stripe rust (Yr) (Puccinia striiformis f. sp. tritici), leaf rust (Lr) (P. triticina), tan spot (TS) (Pyrenophora triticirepentis), and Karnal bunt (KB) (Tilletia indica) are important diseases that adversely affect yield and quality of bread wheat (Triticum aestivum L.) throughout the world. Tritici), leaf rust (Lr) (P. triticina), tan spot (TS) (Pyrenophora triticirepentis), and Karnal bunt (KB) (Tilletia indica) are important diseases that adversely affect yield and quality of bread wheat (Triticum aestivum L.) throughout the world. Regional differences in severity and incidence are pronounced for these diseases. KB is very difficult to control once it is introduced into an area and its potential impact on the grain industry remains high because of quarantine against the disease. The identification and introgression of broad genetic base resistance in commercially grown wheat cultivars is the most cost effective and environmentally safe means to manage wheat diseases. Leaf rust, tan spot, and Karnal bunt are economically significant diseases impacting wheat production. The objectives of this study were to identify quantitative trait loci for resistance to these diseases in a recombinant inbred line (RIL) from a cross HD29/WH542, and to evaluate the evidence for the presence loci on chromosome region conferring multiple disease resistance
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