Marker aided improvement of Pusa 6B, the maintainer parent of rice hybrid Pusa RH10, for resistance to bacterial blight

Abstract

The present study was under taken to transfer two bacterial blight resistance genes, xa13 and Xa21 into Pusa6B, the maintainer parent of Pusa RH10 (PRH 10), the first superfine grain aromatic rice hybrid. Marker aided foreground selection for genes xa13 and Xa21 was carried out using a CAPS marker RG136 and STS marker pTA248, respectively. Forty Six STMS markers polymorphic between Pusa 6B and Pusa1460 providing genome wide coverage were used for background selection for recovering recurrent parent genome. Marker aided selection was combined with phenotypic selection for agronomic, grain and cooking quality traits to hasten the breeding process. In each backcross generation, based on background selection, a single plant positive for genes xa13 and Xa21 was selected for further backcrossing/ selfing. The extent of recurrent parent genome recovery in the 9 BC2F2 plants, carrying both the genes in homozygous condition, ranged from 92.3% to 95.6%. All the plants of BC2F3 families were found highly resistant to BB on artificial inoculation with the most virulent Kaul isolate of Xoo. The improved lines of Pusa 6B showed highly resistant reaction with susceptibility index (SI) ranging from 0.5 to 1.5 as compared to 1.2 of donor parent Pusa 1460 and 9.2 of recurrent parent Pusa 6B. The agronomic performance, grain and cooking quality attributes of majority of the BC2F3 plants were similar to Pusa 6B. However, some plants showed improvement in spikelet fertility, aroma, grain length and L/B ratio. Some of the BC2F3 families matured a few days earlier than the recurrent parents, which will be useful in synchronization of parental lines in hybrid seed production.