Abstract
Symbiotic plant-fungi interaction is a promising approach to alleviate salt stress in plants. Moreover, endophytic fungi are well known to promote the growth of various crop plants. Herein, seven fungal endophytes were screened for salt tolerance; the results revealed that Aspergillus ochraceus showed a great potentiality in terms of salt tolerance, up to 200 g L−1. The indole acetic acid (IAA) production antioxidant capacity and antifungal activity of A. ochraceus were evaluated, in vitro, under two levels of seawater stress, 15 and 30% (v/v; seawater/distilled water). The results illustrated that A. ochraceus could produce about 146 and 176 µg mL−1 IAA in 15 and 30% seawater, respectively. The yield of IAA by A. ochraceus at 30% seawater was significantly higher at all tryptophan concentrations, as compared with that at 15% seawater. Moreover, the antioxidant activity of ethyl acetate extract of A. ochraceus (1000 µg mL−1) at 15 and 30% seawater was 95.83 ± 1.25 and 98.33 ± 0.57%, respectively. Crude extracts of A. ochraceus obtained at 15 and 30% seawater exhibited significant antifungal activity against F. oxysporum, compared to distilled water. The irrigation of barley plants with seawater (15 and 30%) caused notable declines in most morphological indices, pigments, sugars, proteins, and yield characteristics, while increasing the contents of proline, malondialdehyde, and hydrogen peroxide and the activities of antioxidant enzymes. On the other hand, the application of A. ochraceus mitigated the harmful effects of seawater on the growth and physiology of barley plants. Therefore, this study suggests that the endophytic fungus A. ochraceus MT089958 could be applied as a strategy for mitigating the stress imposed by seawater irrigation in barley plants and, therefore, improving crop growth and productivity.
Highlights
IntroductionCrop plants are often exposed to unfavorable environmental conditions, including abiotic stresses that lead to annual losses in crop productivity all over the world [1,2]
Salinity is one of the major abiotic stresses that occur in irrigated and non-irrigated regions, leading to fierce effects on plant growth and production, in crop plants which exhibited a reduction in seed germination, plant growth, and plant biomass [3]
Plants grown under salinity stress conditions accumulate excessive amounts of salt, generating physicochemical disturbances resulting in oxidative stress, suppression of photosynthesis, generation of reactive oxygen species (ROS), and metabolic disorders, all of which contribute to a decrease in plant growth and yields [8,9]
Summary
Crop plants are often exposed to unfavorable environmental conditions, including abiotic stresses that lead to annual losses in crop productivity all over the world [1,2]. Salinity is one of the major abiotic stresses that occur in irrigated and non-irrigated regions, leading to fierce effects on plant growth and production, in crop plants which exhibited a reduction in seed germination, plant growth, and plant biomass [3]. The continued exposure of plants to salt stress resulted in the toxicity of specific ions and nutrients, hormonal imbalance, and a decrease in water potential [4]. Plants grown under salinity stress conditions accumulate excessive amounts of salt, generating physicochemical disturbances resulting in oxidative stress, suppression of photosynthesis, generation of reactive oxygen species (ROS), and metabolic disorders, all of which contribute to a decrease in plant growth and yields [8,9]
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