Drought and heavy metals are major stressors that impair soil health and crop productivity, with drought intensifying metal toxicity through reduced moisture and increased mobility. This study isolated and identified hyper-tolerant endophytic fungus, Trichoderma sp. Ghadah-K4 from Solanum incanum, capable of improving wheat yield and quality under combined drought and heavy metal stress. The strain exhibited strong plant growth-promoting traits and metals tolerance, with elevated activity under drought, and metals stress compared to non-stressed conditions. Strain Ghadah-K4 exhibited significant increases in plant growth-promoting traits, including ACC deaminase (34.51 ± 4.37 to 56.23 ± 5.19 µM/mg/h), ammonia (1.56- to 2.52-fold), zeatin (110.38 ± 5.82 to 140.26 ± 7.00 µg/mL), indole-3-acetic acid (121.17 ± 5.46 to 142.00 ± 6.21 µg/mL), gibberellic acid (32.16 to 66.37%), siderophores (90.25 ± 2.78 to 98.40 ± 3.28%), abscisic acid (120.10 ± 6.28 to 153.22 ± 6.77 µg/mL), and solubilized phosphate (278.40 ± 7.0 to 316.00 ± 8.88 μg/mL), under individual stress from Ni2+, Cd2+, Fe3+, Co2+, Cr6+, Zn2+, Mn2+, Cu2+, and Pb2+ at 600 mM. Similarly, Trichoderma sp. Ghadah-K4 produced high levels of zeatin (84.75–124.8 µg/mL), gibberellic acid (80.17–108.36 µg/mL), indole-3-acetic acid (21.58–36.80%), abscisic acid (1.20- to 1.45-fold), siderophores (100%), ammonia (15.65–20.11 µg/mL), ACC deaminase (39.16–70.15 µM/mg/h), and phosphatase solubilization (270.75–317.18 µg/mL), with increasing water stress from − 0.32 to − 1.40 MPa. Trichoderma sp. Ghadah-K4 enhanced drought and heavy metal tolerance across multiple wheat cultivars including Jazan-181, Najran-193, Suama-357, Rafha-377, Maayah-562, and Najed-981under combined stress, improving germination percentage, dry/fresh weights of roots/shoots, roots/shoots elongation, seed numbers and weights, as well as improved levels of relative water, soluble sugar, protein, and carotenoids. The strain also boosted antioxidant and osmolyte defense (peroxidase, superoxide dismutase, catalase, proline, glycine betaine, and total phenolic) while reducing electrolyte leakage and malondialdehyde. These results highlight Ghadah-K4 is potential as a sustainable bioinoculant for wheat in arid, metal-contaminated soils.

Mitigating drought and heavy metals stress in Triticum aestivum L. using multi-trait tolerant plant growth-promoting endophytic Trichoderma sp. Ghadah-K4

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发表日期：

2026年1月20日

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Ghadah Khaled Yousuf

摘要

Drought and heavy metals are major stressors that impair soil health and crop productivity, with drought intensifying metal toxicity through reduced moisture and increased mobility. This study isolated and identified hyper-tolerant endophytic fungus, Trichoderma sp. Ghadah-K4 from Solanum incanum, capable of improving wheat yield and quality under combined drought and heavy metal stress. The strain exhibited strong plant growth-promoting traits and metals tolerance, with elevated activity under drought, and metals stress compared to non-stressed conditions. Strain Ghadah-K4 exhibited significant increases in plant growth-promoting traits, including ACC deaminase (34.51 ± 4.37 to 56.23 ± 5.19 µM/mg/h), ammonia (1.56- to 2.52-fold), zeatin (110.38 ± 5.82 to 140.26 ± 7.00 µg/mL), indole-3-acetic acid (121.17 ± 5.46 to 142.00 ± 6.21 µg/mL), gibberellic acid (32.16 to 66.37%), siderophores (90.25 ± 2.78 to 98.40 ± 3.28%), abscisic acid (120.10 ± 6.28 to 153.22 ± 6.77 µg/mL), and solubilized phosphate (278.40 ± 7.0 to 316.00 ± 8.88 μg/mL), under individual stress from Ni²⁺, Cd²⁺, Fe³⁺, Co²⁺, Cr⁶⁺, Zn²⁺, Mn²⁺, Cu²⁺, and Pb²⁺ at 600 mM. Similarly, Trichoderma sp. Ghadah-K4 produced high levels of zeatin (84.75–124.8 µg/mL), gibberellic acid (80.17–108.36 µg/mL), indole-3-acetic acid (21.58–36.80%), abscisic acid (1.20- to 1.45-fold), siderophores (100%), ammonia (15.65–20.11 µg/mL), ACC deaminase (39.16–70.15 µM/mg/h), and phosphatase solubilization (270.75–317.18 µg/mL), with increasing water stress from − 0.32 to − 1.40 MPa. Trichoderma sp. Ghadah-K4 enhanced drought and heavy metal tolerance across multiple wheat cultivars including Jazan-181, Najran-193, Suama-357, Rafha-377, Maayah-562, and Najed-981under combined stress, improving germination percentage, dry/fresh weights of roots/shoots, roots/shoots elongation, seed numbers and weights, as well as improved levels of relative water, soluble sugar, protein, and carotenoids. The strain also boosted antioxidant and osmolyte defense (peroxidase, superoxide dismutase, catalase, proline, glycine betaine, and total phenolic) while reducing electrolyte leakage and malondialdehyde. These results highlight Ghadah-K4 is potential as a sustainable bioinoculant for wheat in arid, metal-contaminated soils.