Introgression of durable blast resistance gene Pi-54 into indica rice cv. samba mahsuri, through Marker Assisted Backcross Breeding

Blast disease is one of the most significant diseases of rice, where severe infection results in more than 80% reduction in yield. It is caused by Pyricularia oryzae. New breeding strategies are essential for developing durable blast resistant varieties. The present study aimed to introgress Pi-54 gene from highly blast resistant genotype i.e. Tetep into elite rice cultivar Samba Mahsuri (BPT 5204),   high yielding rice variety with  good cooking quality ,but  susceptible to blast disease, through Marker-Assisted Backcross Breeding programme (MABB). For foreground selection tightly linked molecular marker specific to Pi-54 gene (i.e. Pi-54MAS) which is located on chromosome 11, and it is utilized at each backcrossed generation to identify plants carrying heterozygous alleles for the targeted resistant gene. A total of 56 background markers were used to estimate the recovery of recurrent parent genome in each backcrossed generations. At BC2F2, a single plant carrying the targeted resistant gene Pi-54 with maximum recovery of recurrent parent genome (~92.80%; plant BT-8-47-22) was selected and forwarded to next generations through the selfing. Ancestry based selection procedure was employed for phenotypic disease screening and agro-morphological traits. Results confirmed that, resistance gene (Pi-54) was successfully incorporated into Samba Mahsuri. Six lines viz., BT-8-47-22-6-36, BT-8-47-22-6-55, BT-8-47-22-6-117, BT-8-47-22-6-159, BT-8-47-22-6-203 and BT-8-47-22-6-267 were identified at BC2F4 which were possessing high level of resistance to blast and agro-morphological traits similar to Samba Mahsuri. One NIL line (BT-8-47-22-6-203) was found to be better than recurrent parent Samba Mahsuri (BPT 5204) regarding grain yield per plant. This finding will be helpful in developing a blast resistant variety with highest recurrent parent genome recovery in less number of generations through the application of MABB.