Marker Assisted Gene Pyramiding for Bacterial Blight Resistance in Some Improved Rice Genotypes

Bacterial blight is one of the major diseases of rice, causing huge economic loss to the rice farmers around the world. In the present study, marker assisted selection (MAS) was used to pyramid broad spectrum resistance genes (Xa33 and Xa38) into two improved rice genotypes (ADT 47 and ASD 16) which already have some bacterial blight resistance genes (xa5, xa13 and Xa21). The rice genotypes FBRI-15 and PR114 were used as donors of Xa33 and Xa38 genes respectively. The marker RMWR7.1 linked to Xa33 and the sequenced-tagged site marker Os04g53050-1 specific to Xa38 were used for foreground selection. True F1 hybrids were selected using the polymorphic markers. Out of one hundred and thirty-seven SSR markers, forty-two were polymorphic for improved ADT 47 x FBRI-16 and forty-six were polymorphic for Improved ASD 16 x PR114. The polymorphic markers were used for background selection. Foreground selection revealed that a single F1 plant was heterozygote in Improved ADT 47 X FBRI-15 whereas two plants were heterozygotes in Improved ASD 16 x PR114. At BC1F1, one and three plants were found to be heterozygous respectively for Improved ADT 47 x FBRI-15 and Improved ASD 16 x PR114. At BC2F1, single plant each was found heterozygous from the two crosses. In the final BC3F1 population, one heterozygote each was obtained from the two crosses. In BC3F1, plant number 11 had 92.80% parental genome recovery in the Improved ADT 47 x FBRI-15, whereas plant no 16 had 91.33% parental genome recovery in the Improved ASD 16 x PR114