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Submergence is a major threat in rice growing areas of South and South-East Asia. Identification of a major QTL, Sub1 and advancements in marker-assisted backcrossing strategy enabled breeders to develop submergence tolerant versions of popular rice cultivars. In the present study, a marker-assisted backcross breeding (MABB) approach was used to introgress the Sub1 locus from the tolerant FR13A variety into CO 43, one of the popular rice varieties of southern India. Evaluation of early generation segregating progenies derived from the cross of CO 43 and FR13A revealed the introgression of Sub1, leading to increased tolerance to submergence and better revival ability after it. Genotyping and phenotyping of BC3F3 generation resulted in elite NILs of CO 43 harbouring Sub1 the locus and possessing 94.37% and 95.78% of the recurrent parental CO 43 genome. Selected NILs performed equal as the recurrent parent CO 43 under normal conditions, but were more tolerant to submergence and revived better, afterwards. Under flooding NILs yielded about 25–30% higher than the recurrent parent CO 43.