title: Phenotyping at hot spots and tagging of QTLs conferring spot blotch resistance in bread wheat.
abstract: Spot blotch is a major foliar disease of wheat caused by Bipolaris sorokiniana in warm and humid environments of the world including South Asian countries. In India, it has a larger impact in Indo-Gangetic plains of the country. Therefore, the present study was undertaken to phenotype a mapping population at different hot spots of India and to detect quantitative trait loci (QTL) for resistance to spot blotch in wheat. For this study, 209 single seed descent (SSD) derived F8, F9, F10recombinant inbred lines (RILs) of the cross 'Sonalika' (an Indian susceptible cultivar)/'BH 1146' (a Brazilian resistant cultivar) were assessed for spot blotch resistance at two hot spot locations (Coochbehar and Kalyani) for three years and for two years under controlled conditions in the polyhouse (Karnal). The population showed large variation in spot blotch reaction for disease severity in all the environments indicating polygenic nature of the disease. Microsatellite markers were used to create the linkage maps. Joint and/or individual year analysis by composite interval mapping (CIM) and likelihood of odds ratio (LOD) >2.1, detected two consistent QTLs mapped on chromosome 7BL and 7DL and these explained phenotypic variation of 11.4 percent and 9.5 percent over the years and locations, respectively. The resistance at these loci was contributed by the parent 'BH 1146' and shown to be independent of plant height and earliness. Besides, association of some agro-morphological traits has also been observed with percent disease severity. These identified genomic regions may be used in future wheat breeding programs through marker assisted selection for developing spot blotch resistant cultivars.
authors: Indian Institute of Wheat and Barley Research, Karnal, India.|Department of Bio and Nano Technology, Bio and Nano Technology Centre, Guru Jambheshwar University of Science and Technology, Hisar, India.
authors: Virender
authors: V
authors: Singh
authors: Indian Institute of Wheat and Barley Research, Karnal, India.
authors: Gyanendra
authors: G
authors: Singh
authors: Department of Bio and Nano Technology, Bio and Nano Technology Centre, Guru Jambheshwar University of Science and Technology, Hisar, India.
authors: A
authors: A
authors: Chaudhury
authors: Indian Institute of Wheat and Barley Research, Karnal, India.
authors: Ashish
authors: A
authors: Ojha
authors: Indian Institute of Wheat and Barley Research, Karnal, India.
authors: B S
authors: BS
authors: Tyagi
authors: Uttar Banga Krishi Viswavidyalaya, Pundibari, Coochbehar, India.
authors: A K
authors: AK
authors: Chowdhary
authors: Indian Institute of Wheat and Barley Research, Karnal, India. sheoran_sonia@yahoo.co.in.
authors: Sonia
authors: S
authors: Sheoran
mesh_terms: D001203:Ascomycota / Q000472:pathogenicity; D001947:Breeding; D002874:Chromosome Mapping; D060467:Disease Resistance; D017343:Genes, Plant; D018895:Microsatellite Repeats; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D040641:Quantitative Trait Loci; D014908:Triticum / Q000235:genetics*
keywords: Bipolaris sorokiniana; Phenotyping; QTL mapping; Spot blotch; Wheat