Marker assisted pyramiding of drought tolerant QTLs qDTY 1.1 and qDTY 3.1 in rice variety Samba Mahsuri Sub-1
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Date
2020-10
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College of Post Graduate Studies in Agricultural Sciences, CAU-Imphal, Umiam
Abstract
Water deficit is one of the most important abiotic factors causing huge loss in rice productivity. Therefore, the present study was aimed to develop a multiple stress tolerant genotype by pyramiding drought tolerant yield QTLs qDTY1.1 and qDTY3.1 into high yielding rice variety Samba Mahsuri Sub-1(SMS) through Marker Assisted Pyramiding (MAS). This was achieved by crossing six introgression lines of SMS carrying qDTY1.1 (SAB lines) with DRR-50, a released variety carrying qDTY3.1. The SAB lines are taller than SMS due to tight linkage between qDTY1.1 and wild type SD-1 that could not be broken during backcrossing. Therefore, the study also focused on screening the F2 generation of crosses for recombinants between SD-1 gene and qDTY1.1 on chromosome 1. From the 35 F1 hybrids obtained, three F2 populations from crosses DRR-50 X SAB-4-2-20 and DRR-50 X SAB 7-13-5 were grown in the field in Kharif, 2019 and about 1530 F2 plants were screened. Desired recombinants were not obtained from DRR-50 X SAB 7-13-5 population. 305 dwarf F2 plants were phenotypically selected and screened for the presence of qDTY1.1. Three dwarf F2 plants having qDTY1.1 were obtained. These three lines along with three others carrying qDTY1.1 and qDTY3.1 were forwarded to F3 generation. From the six SABD F3 lines fourteen pyramided lines were selected and forward to F4 generation. The six SABD F3 lines SABD-7, SABD-8, SABD-9, SABD-76, SABD-79 and SABD-80 along with parents were evaluated under moisture stress for various physiological parameters. The soil moisture content decreased drastically during the reproductive stage compared to vegetative stage when irrigation was withheld for 15 days during both the stages. Chlorophyll content and Relative Water Content (RWC) was more; canopy temperature and malonaldehyde (MDA) content were lesser in SABD lines when compared to parents indicating tolerance under water stress. Variance due to genotypes was found to be highly significant for all the yield related traits except for test weight. Variance among irrigated and moisture stress conditions for all the parameters was found to be non-significant except for panicle number, panicle length and test weight. The GXE interaction was found to be significant for tiller number, grains/panicles and harvest index. SABD-9, SABD-76, SABD-79 and SABD-80 were performing better for most of the morphological and physiological parameters, exhibiting greater tolerance for drought when compared to other pyramided lines and parents under moisture stressed conditions. The present study was done to identify recombinants between qDTY1.1 and sd-1; and progeny fixed for qDTY1.1 and qDTY3.1. However, fixed lines for all the 3 loci could not be confirmed. Further progeny screening/hybridization is required in order to fix all the 3 loci i.e., qDTY1.1, sd-1 and qDTY3.1 in the same genotype.