Molecular Insights into Drought Tolerance: Biochemical and Genetic Diversity Analysis of Groundnut Genotypes with Emphasis on DREB2C

Groundnut ( Arachis hypogaea L .), a globally important oilseed crop, is extensively cultivated in India. In this study, 25 groundnut genotypes were evaluated under control and drought stress conditions to assess their biochemical and molecular responses. The genotype GG-37 exhibited the greatest decline in chlorophyll content (0.674 mg/g), whereas GJG-9 showed the least reduction (0.126 mg/g). The variation in H ₂ O ₂ ranged from − 0.112 to 0.777 µmol/g FW, total soluble sugars from − 14.45 to 36.92 mg/g FW, and proline from − 74.12 to 269.86 µg/g FW, highlighting genotype-dependent stress responses. Gene expression analysis via qRT-PCR revealed that DREB2C was most highly upregulated in GJG-9, with significant expression also observed in GG-38, GG-41, JB-1697, and JB-1694. Conversely, GG-37 and GG-40 exhibited strong downregulation. A total of 16 SSR primers amplified 42 alleles, of which 33 (78.57%) were polymorphic. The primer AHM-689 produced the highest number of bands (8). Polymorphism Information Content (PIC) ranged from 0 to 0.84 (average 0.37), and the SSR Primer Index (SPI) ranged from 0 to 4.21 (average 1.83). Unique bands were observed in specific genotypes e.g., primer pPGSseq9H8 produced two bands unique to JB-1690, while JAUGP-341 generated a unique band specific to GG-20. UPGMA-based cluster analysis grouped genotypes into two major clusters, with genetic similarity coefficients ranging from 47.61% to 100%. The most divergent pair was JB-1690 and JB-1696, while JB-1694, JB-1697, and JB-1698 showed complete similarity.