Introgression of AG Gene into the elite submergence tolerant rice cultivar CR Dhan 801 through Marker Assisted Backcross breeding

Abstract

Rice, a preeminent staple sustaining a considerable proportion of the global newlinepopulace, grapples with formidable challenges in waterlogged ecosystems, especially during newlinethe critical germination phase under anaerobic conditions. Given the intrinsic significance of newlinerice in global food security, particularly in regions prone to flooding, the imperative to newlinecultivate flood-tolerant rice varieties is unequivocal. This study posits the strategic utilization newlineof Marker-Assisted Back Crossing (MABC) to introgress Quantitative Trait Loci (QTLs) newlineassociated with anaerobic germination tolerance into the distinguished rice variety CR Dhan newline801. A meticulous initial screening encompassing 266 genotypes delineated the spectrum of newlineanaerobic germination capabilities. Five entries, notably Tulasi Phula, Pani Rohi, AG 387, newlineBJ 1, and Chinamali, exhibited germination rates surpassing 75%, while 33 entries newlinedemonstrated rates between 50% and 75%, and 228 entries exhibited less than 50% newlinegermination. This pronounced heterogeneity in germination performance underscored the newlineimperative need for targeted genetic enhancement for anaerobic germination. The study newlinescrutinized pivotal traits governing anaerobic germination tolerance, including shoot length, newlinelength of the first internode, root length, number of leaves, and seedling dry weight (both newlineshoot and root dry weight). Genetic mapping techniques, namely Interval Mapping (IM) and newlineInclusive Composite Interval Mapping (ICIM), facilitated the identification of 38 QTLs and newline33 QTLs respectively, associated with anaerobic germination linked essential traits. newlineSubsequent to the delineation of QTLs, Marker-Assisted Backcross Breeding (MABB) was newlineemployed to introgress two key QTLs, namely qAG2.1 on chromosome 2 and qAG6.1 on newlinechromosome 6, elucidating phenotypic variances of 12.4% and 3.4%, respectively, into the newlinegenetic background of CR Dhan 801. The strategic incorporation of 21 BC2F3 lines, guided newlineby foreground and background selections facilitated the identification of promising newlinegenotypes. Prominent am