Abstract
Basmati rice grown in the Indian subcontinent is highly valued for its unique culinary qualities. Production is, however, often constrained by diseases such as bacterial blight (BB), blast and sheath blight (ShB). The present study developed Basmati rice with inbuilt resistance to BB, blast and ShB using molecular marker-assisted selection. The rice cultivar 'Improved Pusa Basmati 1' (carrying the BB resistance genes xa13 and Xa21) was used as the recurrent parent and cultivar 'Tetep' (carrying the blast resistance gene Pi54 and ShB resistance quality trait loci (QTL), qSBR11-1) was the donor. Marker-assisted foreground selection was employed to identify plants possessing resistance alleles in the segregating generations along with stringent phenotypic selection for faster recovery of the recurrent parent genome (RPG) and phenome (RPP). Background analysis with molecular markers was used to estimate the recovery of RPG in improved lines. Foreground selection coupled with stringent phenotypic selection identified plants homozygous for xa13, Xa21 and Pi54, which were advanced to BC(2)F(5) through pedigree selection. Marker-assisted selection for qSBR11-1 in BC(2)F(5) using flanking markers identified seven homozygous families. Background analysis revealed that RPG recovery was up to 89.5%. Screening with highly virulent isolates of BB, blast and ShB showed that the improved lines were resistant to all three diseases and were on a par with 'Improved Pusa Basmati 1' for yield, duration and Basmati grain quality. This is the first report of marker-assisted transfer of genes conferring resistance to three different diseases in rice wherein genes xa13 and Xa21 for BB resistance, Pi54 for blast resistance, and a major QTL qSBR11-1 have been combined through marker-assisted backcross breeding. In addition to offering the potential for release as cultivars, the pyramided lines will serve as useful donors of gene(s) for BB, blast and ShB in future Basmati rice breeding programmes.
Highlights
Basmati rice cultivated in the north-western part of the Indo-Gangetic plains of the Indian subcontinent is highly valued in the international market due to its unique combination of aroma, grain, cooking and eating qualities (Singh et al 1988, 2000)
Singh et al — Molecular breeding of multiple disease-resistant Basmati rice. This is the first report of marker-assisted transfer of genes conferring resistance to three different diseases in rice wherein genes xa13 and Xa21 for bacterial blight (BB) resistance, Pi54 for blast resistance, and a major QTL qSBR11-1 have been combined through marker-assisted backcross breeding
In addition to offering the potential for release as cultivars, the pyramided lines will serve as useful donors of gene(s) for BB, blast and sheath blight (ShB) in future Basmati rice breeding programmes
Summary
Basmati rice cultivated in the north-western part of the Indo-Gangetic plains of the Indian subcontinent is highly valued in the international market due to its unique combination of aroma, grain, cooking and eating qualities (Singh et al 1988, 2000). Oryzae, blast caused by Magnoporthae oryzae and sheath blight (ShB) caused by Rhizoctonia solani cause severe yield losses and impair the quality of the rice grain (Singh et al 2011). In the case of Basmati rice, economic losses from reduced yield are amplified by a severe deterioration in quality. The rice cultivar ‘Improved Pusa Basmati 1’ (carrying the BB resistance genes xa and Xa21) was used as the recurrent parent and cultivar ‘Tetep’ (carrying the blast resistance gene Pi54 and ShB resistance quality trait loci (QTL), qSBR11-1) was the donor. The SSR markers, which were polymorphic, were used to identify plants with maximum recovery of recurrent parent genome (RPG) in BC2F5 generation. The genomic contribution of the parents in the elite selections was analysed and represented using the software Graphical Geno Types (GGT) Version 2.0 (Van Berloo 1999).
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