Promising versions of a commercial pearl millet hybrid for terminal drought tolerance identified through MAS

Extreme climatic conditions like drought are a major threat to global food production. Terminal drought stress causes severe yield losses in pearl millet. Development of climate-resilient varieties/hybrids can minimize the yield losses to the farmers caused due to climatic extremes. In the present study, marker-assisted selection (MAS) was employed with an aim to develop improved version of HHB 226 by introgression of QTLs for terminal drought stress tolerance into the male parent of the hybrid (HBL 11). HBL 11 (recurrent parent) was crossed with PRLT 2 (donor) to develop F₁ and backcrossed four times to raise BC₄F₁ and further selfed twice to raise BC₄F₃. Four polymorphic SSR markers were used to track the QTL introgressed lines in each subsequent generation until BC₄F₂. The recurrent parent genome recovery was assessed using 25 polymorphic SSRs. Morpho-physiological analysis of BC₄F₃ generation at field-level under terminal drought stress conditions showed that the QTL introgressed lines showed higher, grain yield, 1000-seed weight, relative water content (%), and lower electrolyte leakage (%) than the recurrent parent. Line number 63 performed best with all the four foreground markers, 97.20% recurrent parent genome recovery, 7.27 g 1000-seed weight, 73.27% relative water content, 65.06% electrolyte leakage, 0.58 (fv/fm) chlorophyll fluorescence, and 53.25 g grain yield per plant. Finally, the Improved version of HHB 226 was developed by using the Improved HBL 11 developed through MAS. Besides this, HBL 11 is the male parent of other commercial hybrids like HHB 223 and HHB 197 as well making Improved HBL 11 an asset to improve these pearl millet hybrids.