Marker-Assisted Introgression of qSPP2.2 Loci from Oryza longistaminata Improves Spikelet Number in Basmati Rice
2025
Debnath, S | Neelam, K | Bhatia, D | Kaur, A | Kumar, Kishor | Singh, K
Basmati rice is the premium, export-quality, long, slender grains with pleasant aroma. Punjab Basmati 3 (PB3), a unique aromatic rice, is sensitive to photoperiod, semi-dwarf, tolerant to lodging, and resistant to bacterial blight (BB). However, it yields less than Indica varieties, mostly due to lower number of grains per panicle (GPP), which varies between 60 and 80. To increase the GPP in PB3, we transferred the grain number QTL qSPP2.2 from O. longistaminata (A. Chev. et Roehr.) derived introgression line, RIL127 into PB3 using marker-assisted selection (MAS). Marker- assisted foreground selection using polymorphic markers linked to the qSPP2.2 loci in plants from backcross progenies and their advanced self-progenies, coupled with their background analysis for BB resistance (Xa21, xa13), Basmati aroma (Badh2) and intermediate amylose content (wx locus) and analysis of their grain quality characteristics ensured an efficient and successful introgression of the QTL qSPP2.2 into PB3. The phenotypic expression of qSPP2.2 in the Basmati background was studied in BC1F2, BC2F3 and their advanced selfed progenies, and it shows a 35–40% increase in the grain number of PB3, demonstrating a significant improvement of grain yield of the introgressed lines. Together, a large number of backcross progenies and their advanced self-progenies, coupled with MAS for desirable alleles, and extensive phenotyping have resulted in an improved version of PB3 with higher spikelet per panicle (SPP). Correlation analysis using 384 replicated F2 plants revealed no significant correlation between SPP and grain length, however, a significant weak negative correlation (-0.150*) was observed between SPP and grain breadth, suggesting the possibility of raising the GPP and the total output of Basmati rice having exceptional quality.
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