“LINKAGE AND QTL MAPPING FOR BLAST RESISTANCE IN PEARL MILLET (Pennisetum glaucum (L.) R. Br.)”2507
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Date
2018-02
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JAU,JUNAGADH
Abstract
Key words: Linkage, QTL, BLAST, Linkage group, SSR, LOD.
Present experiment on “LINKAGE AND QTL MAPPING FOR BLAST RESISTANCE IN PEARL MILLET (Pennisetum glaucum (L.) R. Br.)” was conducted at Department of Biotechnology, Junagadh Agricultural University, Junagadh. The study was formulated to improve the yield potential of hybrids of J-2537, which is one of the elite and important restorer lines used in hybrid breeding programs in Gujarat. Identification of blast resistance genomic regions was set as an objective.
Blast disease of pearl millet is one of the most important devastating and limiting pearl millet productivity. The DNA-based marker tools facilitate better understanding of the inheritance and expression of blast. To fulfill the objectives, two pearl millet inbred parental lines viz, ICMB – 95444 x J – 2537 were crossed to produce F1 and the F1 progenies were selfed to produce mapping population comprising of 36 segregating F2 progenies for generating marker data using 55 SSR out of 100 markers exhibiting clear polymorphism between parental lines. The blast screening of segregating F2 population progenies against Blast was done at JAU, Jamnagar.
R-QTL interval mapping method identified two blast QTLs on Linkage Group 1 and Linkage Group 6. This best single-QTL model detected by interval mapping on Linkage Group 1 (BRP11 marker) recorded a high LOD score of 8.2 and explained 46.4% phenotypic variation with map position 15.8 Linkage Group 6 (BRP37 marker) recorded a high LOD score of 1.6 and explained 36% phenotypic variation in blast incidence among 36 F2 progenies against Pyricularia grisea pathogen.
The confidence interval detected that the position between 10-18 cM on linkage group 1 was responsible for the resistance against blast in pearl millet. The effect plot for marker BRP11 indicated that the resistance against the blast was governed by dominant inheritance and can be easily used for the transfer of trait through marker assisted selection using marker BRP11.
In present study, blast resistant QTLs descended from resistant male parent J – 2537 exhibited over-dominance mode of inheritance, and Blast resistant QTLs from resistant male parent J-2537. These identified Blast QTLs from J-2537 can now be transferred to genetic backgrounds of elite pearl millet hybrid parental lines (ICMB – 95444) through marker-assisted backcrossing programs. Flanking markers of the identified QTLs can facilitate selection of resistant progenies during the backcrossing process, where as other marker loci can be used in reducing the length of the donor segments carried along with the introgressed blast resistant genes and/or selecting for recovery of recurrent parent alleles on non-carrier chromosomes.
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BIOTECHNOLOGY