What question did this study set out to answer?

The aim is to explore adaptive mechanisms for drought tolerance in different soybean genotypes.

February 12, 2026Open Access

Integrated physiological, biochemical, and molecular analysis of drought tolerance in soybean cultivars

Puntos clave

The aim is to explore adaptive mechanisms for drought tolerance in different soybean genotypes.
Conducted pot experiments under controlled conditions with seven soybean genotypes.
Measured physiological traits such as relative water content, chlorophyll content, and photosynthetic rate.
Evaluated biochemical indicators including proline, glycine betaine, and antioxidant enzyme activities.
Performed qRT-PCR for gene expression analysis of drought-responsive genes.
Applied multivariate analyses to investigate correlations among traits.
Tolerant genotypes maintained higher relative water content (>80%) and chlorophyll (≥1.73 g g −1 FW) under drought conditions.
Enhanced accumulation of osmolytes like proline (up to 47.5 µg g −1 FW) and glycine betaine (up to 157 µg g −1 FW) in tolerant genotypes.
Significantly higher antioxidant enzyme activities in tolerant genotypes compared to susceptible ones.
Higher expression of stress-responsive genes, with GmP5CS showing a ~3.8-fold increase in tolerant genotypes.

Resumen

Drought stress is an important constraint to soybean (Glycine max L. Merr.) production, specifically in arid and semi-arid regions. This study integrated physiological, biochemical, and molecular approaches to elucidate the adaptive mechanisms of soybean genotypes against drought stress. Seven genotypes, four tolerant, ‘Ajmeri’, ‘NARC-21’, ‘DMX4561’ and ‘Rawal’, and three susceptible ‘Anjasmoro’, ‘Grobogan’, ‘Dering-1’ were evaluated under control and drought conditions in a pot experiment conducted under controlled conditions. Physiological traits, including relative water content (RWC), chlorophyll content, photosynthetic rate (Pn), and cell membrane stability (CMS), were quantified alongside biochemical indicators such as proline, glycine betaine (GB), and antioxidant enzyme activities. The relative expression of drought-responsive genes, GmDREB2, GmLEA-D11, GmP5CS, GmBADH2, GmSOD1, GmCAT1, GmPOD1, GmPIP2;9, GmCHLG was conducted via qRT-PCR. Results indicated that tolerant genotypes kept higher RWC (80%), chlorophyll (≥1.73 g g −1 FW), Pn (≥30 μmol m −2 s −1 ), and CMS (70%) under drought. They also accumulated more proline (up to 47.5 µg g −1 FW) and GB (up to 157 µg g −1 FW). The activities of antioxidant enzymes, in tolerant genotypes were markedly higher (CAT up to 15.3 U mg −1 protein; SOD 50 U mg −1 protein) than in susceptible genotypes. Besides, the multivariate analyses (correlation, PCA, hierarchical clustering) grouped tolerant genotypes to osmolytes (proline, GB), antioxidant enzymes, and physiological traits, proving strong drought trait association. The expression analysis showed high upregulation of stress-related genes (e.g., GmP5CS ~3.8-fold; GmBADH2 ~3.4-fold; GmSOD1 ~3.5-fold) in tolerant genotypes, rectified the physiochemical findings. Overall, these results proved that drought tolerance in soybean is regulated by the co-ordination of osmolytic adjustment, enhanced antioxidant activities, maintenance of photosynthetic traits, and transcriptional activation of stress-responsive genes. The identified tolerant genotypes will serve as promising breeding resources for the development of stress-tolerant soybean cultivars.

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