The interplay of salt stress and Azolla aqueous extract on ionic balance, secondary metabolism, and gene expression in wheat seedlings.

BACKGROUND

The resilience of plants against environmental challenges, particularly salinity and dehydration, is crucial for global food security. This study delves into the intricate interaction between NaCl-induced salinity and Azolla aqueous extract (AAE). In a pot trial, wheat kernels were primed with deionized water or 0.1% AAE for 21 h. Seedlings underwent various treatments; tap water, 250 mM NaCl, AAE priming and spray, and combined AAE with NaCl treatments. Seedlings were analyzed for ionic balance, secondary metabolism, antioxidant efficacy, and molecular response to experimental treatments.

RESULTS

GC-MS analysis of AAE revealed key components like γ-aminobutyric acid and benzenedicarboxylic acid. Exposure to 250 mM NaCl significantly reduced N, P, Ca, K, and the K/Na ratio, while increases in Mg and Na. Also, salinity significantly decreased TAC, DPPH activity, and AsA levels while increasing GB in wheat seedlings. Additionally, salinity increased flavonoids, saponins, and anthocyanins but non-significantly decreased phenols. qRT-PCR analysis revealed upregulation of DRF1, CBF3, HQT, CHS, and FLS genes and downregulation of CBF4 and CHI genes by salinity. AAE treatments, alone or combined with salt stress, mitigated Na accumulation (31.50 and 32.87% compared to stressed seedlings), improved N and P levels, alleviated Mg, K/Na, and GB imbalances, and enhanced antioxidant potentials. Combined AAE and NaCl treatments effectually restored antioxidant potentials and regulated secondary metabolites and gene expressions, sustaining enhancement of ionic equilibrium, antioxidant defenses, and molecular responses in salt-stressed wheat.

CONCLUSIONS

Overall, AAE can be exploited as a green approach for sustaining normal metabolism and gene expression of wheat seedlings in saline soils.