Introgression of multiple disease resistance into a maintainer of Basmati rice CMS line by marker assisted backcross breeding
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- Singh, A.K., Singh, V.K., Singh, A. et al. Euphytica (2015) 203: 97. doi:10.1007/s10681-014-1267-1
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Globally, blast incited by Magnaporthe oryzae and sheath blight (ShB) by Rhizoctonia solani Kuhn forms two major fungal diseases that cause significant yield loss in rice. Pusa 6B, the Basmati quality maintainer line of the popular superfine grain aromatic rice hybrid Pusa RH10, is highly susceptible to both the diseases. The rice cultivar Tetep was used as the donor for transferring a major blast resistant gene, Pi54 and three ShB resistant quantitative trait loci (QTLs) namely, qSBR11-1, qSBR11-2 and qSBR7-1 into Pusa 6B using a marker assisted backcross breeding scheme with restricted number of backcrosses. Plants heterozygous for the alleles of interest and phenotypic similarity to the recurrent parent were used for generating BC1F2 population by selfing selected BC1F1 plants. Selected BC1F2 plants homozygous for Pi54 were selfed to generate BC1F3 families that were subjected to a step-wise reductive screening for the three ShB resistant QTLs. Final selections were advanced to BC1F5 generation through selfing while subjecting to stringent phenotypic selection. The advanced selections carrying blast and ShB resistant genes (Pi54, qSBR11-1, qSBR11-2, qSBR7-1) in the background of Pusa 6B were resistant to highly virulent strains of rice blast as well as ShB isolates without compromising the grain and cooking quality of Pusa 6B. Marker assisted transfer of blast and ShB resistance into Pusa 6B will aid in developing CMS lines with inbuilt resistance to these diseases. When combined with restorer lines possessing resistant genes/QTLs for these diseases, the improved Pusa6A lines will aid in development of improved Pusa RH10 and other novel aromatic hybrids with resistance to blast and ShB diseases. The present study demonstrates successful use of a restricted backcrossing strategy for introgression of multiple loci conferring resistance to two important fungal diseases in rice.