Introduction
Soil salinity is a major abiotic stress limiting agricultural productivity worldwide. Since breeding crops to increase tolerance to abiotic stresses is very difficult due to the complexity of inheritance of traits related to tolerance to these stresses, in recent years, non-breeding or non-transgenic approaches such as the use of symbiotic microorganisms in plants have been considered, which has led to increased tolerance to abiotic stresses and achieved promising results. Plants have distinct microbial communities in their different organs. There is a lot of evidence about the role of the microbiome in growth, development, response to biotic and abiotic stresses, and increased adaptation to the environment. This study investigated the potential of Penicillium chrysogenum, an endophytic fungus isolated from seeds of the halophyte Bassia scoparia, to improve salinity tolerance in maize (Zea mays L.). Halophyte-associated microbes have shown remarkable ability to confer stress tolerance to crops, but the mechanisms remain poorly understood. Our research aimed to (1) characterize the salt tolerance of P. chrysogenum, (2) evaluate its effects on maize growth under salt stress, and (3) analyze physiological responses in inoculated plants.
Materials and Methods
The fungal strain was isolated from surface-sterilized B. scoparia seeds collected from saline regions in Iran. Molecular identification was performed using ITS sequencing. The salinity tolerance of fungi was evaluated on PDA medium containing 0-4 M NaCl. Maize seeds (cv. Hido) were inoculated with fungal spores and grown under controlled conditions with three salinity levels (0, 30, 60 mM NaCl). Then, greenhouse tests were conducted under two treatments of 150 mM NaCl and normal irrigation. Drought tests were also conducted on plants in the greenhouse. Growth parameters (germination rate, root length, biomass), ion content (Na+, K+), and photosynthetic parameters were measured. Experiments included laboratory, growth chamber, and greenhouse trials with five replicates per treatment. Data were analyzed using ANOVA and Tukey's test (p<0.05).
Results and Discussion
In this study, an endophytic fungus, likely Penicillium chrysogenum, was isolated from the seed microbiome of the halophyte B. scoparia. This fungus exhibited optimal growth at 1 M NaCl, indicating halotolerance. Although it did not significantly affect seed germination, fungal inoculation improved early seedling growth traits and biomass under both saline and normal conditions. Greenhouse experiments confirmed its positive effects on shoot and root development under salt stress, while no beneficial effects were observed under drought conditions.
Interestingly, photosynthetic performance and Na⁺/K⁺ ratios remained unchanged in inoculated plants, suggesting that the fungus may enhance salt tolerance through mechanisms such as salt detoxification or antioxidant enhancement rather than altering ion uptake. Given the fungus’s native origin and its potential role in stress adaptation, P. chrysogenum represents a promising candidate for developing biological solutions to improve crop resilience in saline environments. Further field trials and molecular studies are recommended to optimize its application.
Conclusion
This study demonstrated that Penicillium chrysogenum, an endophytic fungus isolated from the halophyte B. scoparia, can promote maize growth under salt stress. Despite no significant effect on germination rate, fungal inoculation improved seedling establishment and biomass production in both normal and saline conditions. The fungus showed halotolerance and may enhance salt stress resilience through mechanisms unrelated to ion uptake, potentially involving detoxification pathways or antioxidant activity. Given its native origin and efficacy under saline conditions, P. chrysogenum holds potential as a bio-inoculant for improving crop performance in salt-affected soils. Further field trials and molecular studies are recommended to better understand and harness its functional mechanisms. |
