Enhancing saline stress tolerance in soybean seedlings through optimal NH4+/NO3− ratios: a coordinated regulation of ions, hormones, and antioxidant potential

作者：Javaria Noor, Izhar Ahmad, Abd Ullah, Babar Iqbal, Shazma Anwar, Arshad Jalal, Mohammad K. Okla, Ibrahim A. Alaraidh, Hamada AbdElgawad, Shah Fahad · 发表于：BMC Plant Biology · 年份：2024 · DOI：10.1186/s12870-024-05294-z · 被引用次数：31 · 研究领域：Plant Stress Responses and Tolerance、Plant nutrient uptake and metabolism、Plant Micronutrient Interactions and Effects

Abstract Background Nitrogen (N) availability is crucial in regulating plants’ abiotic stress resistance, particularly at the seedling stage. Nevertheless, plant responses to N under salinity conditions may vary depending on the soil’s NH 4 + to NO 3 − ratio. Methods In this study, we investigated the effects of different NH 4 + :NO 3 − ratios (100/0, 0/100, 25/75, 50/50, and 75/25) on the growth and physio-biochemical responses of soybean seedlings grown under controlled and saline stress conditions (0-, 50-, and 100-mM L − 1 NaCl and Na 2 SO 4 , at a 1:1 molar ratio). Results We observed that shoot length, root length, and leaf-stem-root dry weight decreased significantly with increased saline stress levels compared to control. Moreover, there was a significant accumulation of Na + , Cl − , hydrogen peroxide (H 2 O 2 ), and malondialdehyde (MDA) but impaired ascorbate-glutathione pools (AsA-GSH). They also displayed lower photosynthetic pigments (chlorophyll-a and chlorophyll-b), K + ion, K + /Na + ratio, and weakened O 2 •− -H 2 O 2 -scavenging enzymes such as superoxide dismutase, catalase, peroxidase, monodehydroascorbate reductase, glutathione reductase under both saline stress levels, while reduced ascorbate peroxidase, and dehydroascorbate reductase under 100-mM stress, demonstrating their sensitivity to a saline environment. Moreover, the concentrations of proline, glycine betaine, total phenolic, flavonoids, and abscisic acid increased under both stresses compared t...