Fungal Endophytes Enhance Wheat and Tomato Drought Tolerance in Terms of Plant Growth and Biochemical Parameters

Lamiaceae family-derived endophytic fungi: induced tolerance to drought stress in Thymus vulgaris plants

BACKGROUND

Thymus vulgaris is a valuable medicinal plant widely cultivated for its aromatic and medicinal properties. However, like many plants, T. vulgaris faces challenges such as drought stress, which significantly affects its growth, morphological, physiological, and biochemical processes. Understanding how endophytic fungi isolated from Lamiaceae family influence T. vulgaris under varying watering regimes can enhance its resilience against drought stress. This study aims to assess the impact of individual and co-inoculation of three native endophytic species, i.e., Fusarium sp. (F1), Cladosporium puyae (F2), and Curvularia australiensis (F3), on T. vulgaris growth parameters under different irrigation regimes in greenhouse conditions.

RESULTS

It has been discovered that using fungal endophytes as a biological tool can benefits T. vulgaris under drought stress. The results indicated that drought stress significantly reduced the growth, chlorophyll, and carotenoid content of plants lacking endophytes. Combinatory applications with fungal endophytes significantly improved the above-mentioned parameters under drought stress. Lipid peroxidation levels were significantly reduced in plants inoculated with bacterial endophytes. Drought stress significantly increased the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR), peroxidase (POD), and catalase (CAT) in drought conditions.

CONCLUSIONS

The findings suggested that the addition of fungal endophytes to the inoculum enhances drought tolerance in T. vulgaris by mitigating the harmful impact of drought stress on plant growth and physiological functions. The higher activity of antioxidant enzymes and improved redox state of glutathione are responsible for plants' greater resistance to drought.

Seed priming with Metarhizium anisopliae (MetA1) improves physiology, growth and yield of wheat

Microorganisms offer a sustainable way to increase crop production and promote eco-friendly farming. The endophytic fungus Metarhizium anisopliae is known for its multiple roles in plant ecosystems, including plant protection, symbiosis, and abiotic stress mitigation. In this study, we evaluated the potential of seed priming with M. anisopliae isolate MetA1 (MA) to enhance germination, photosynthetic efficiency, growth, and yield of two wheat varieties, BARI Gom 26 (BG26) and BARI Gom 33 (BG33) under field conditions. The study demonstrated that MA seed priming significantly improved wheat germination (by 13% and 26.04%) of BG26 and BG33, respectively. Overall, photosynthetic performance, indicated by increased leaf angle, leaf thickness, relative chlorophyll content, and linear electron flow (LEF), quantum yield of Photo System II (Phi2) was increased in MA primed wheat plants, while reducing non-photochemical quenching like NPQt, PhiNO, PhiNPQ of both varieties. These enhancements were attributed to increased shoot biomass (by 215.64% for BG26 and 280.38% for BG33), root biomass (by 141.79% for BG26 and 207.4% for BG33), effective tiller percentage (by 9.17% for BG26 and 5.7% for BG33), spike length (by 25.05% for BG26 and 25.42% for BG33), grain yield parameters such as filled grain percentage (by 23.8% for BG26 and 12.5% for BG33), and grain weight per plant (by 168.62% for BG26 and 119.62% for BG33). The findings of the research demonstrated the potential of M. anisopliae for field use in an agricultural setting, providing a sustainable means of increasing food production.

The rhizosphere and root selections intensify fungi-bacteria interaction in abiotic stress-resistant plants

The microbial communities, inhabiting around and in plant roots, are largely influenced by the compartment effect, and in turn, promote the growth and stress resistance of the plant. However, how soil microbes are selected to the rhizosphere, and further into the roots is still not well understood. Here, we profiled the fungal, bacterial communities and their interactions in the bulk soils, rhizosphere soils and roots of eleven stress-resistant plant species after six months of growth. The results showed that the root selection (from the rhizosphere soils to the roots) was stronger than the rhizosphere selection (from the bulk soils to the rhizosphere soils) in: (1) filtering stricter on the fungal (28.5% to 40.1%) and bacterial (48.9% to 68.1%) amplicon sequence variants (ASVs), (2) depleting more shared fungal (290 to 56) and bacterial (691 to 2) ASVs measured by relative abundance, and (3) increasing the significant fungi-bacteria crosskingdom correlations (142 to 110). In addition, the root selection, but not the rhizosphere selection, significantly increased the fungi to bacteria ratios (f:b) of the observed species and shannon diversity index, indicating unbalanced effects to the fungal and bacteria communities exerted by the root selection. Based on the results of network analysis, the unbalanced root selection effects were associated with increased numbers of negative interaction (140 to 99) and crosskingdom interaction (123 to 92), suggesting the root selection intensifies the negative fungi-bacteria interactions in the roots. Our findings provide insights into the complexity of crosskingdom interactions and improve the understanding of microbiome assembly in the rhizosphere and roots.

Alleviating the drought stress and improving the plant resistance properties of Triticum aestivum via biopriming with aspergillus fumigatus

BACKGROUND

Wheat (Triticum aestivum L.) is one of the most widely grown and vital cereal crops, containing a high percentage of basic nutrients such as carbohydrates and proteins. Drought stress is one of the most significant limitations on wheat productivity. Due to climate change influences plant development and growth, physiological processes, grain quality, and yield. Drought stress has elicited a wide range of plant responses, namely physiological and molecular adaptations. Biopriming is one of the recent attempts to combat drought stress. Mitigating the harmful impact of abiotic stresses on crops by deploying extreme-habitat-adapted symbiotic microbes. The purpose of this study was to see how biopriming Triticum aestivum grains affected the effects of inoculating endophytic fungi Aspergillus fumigatus ON307213 isolated from stressed wheat plants in four model agricultural plants (Gemmiza-7, Sids-1, Sakha8, and Giza 168). And its viability in reducing drought stress through the use of phenotypic parameters such as root and shoot fresh and dry weight, shoot and root length, and so on. On a biochemical and physiological level, enzymatic parameters such as catalase and superoxidase dismutase are used. Total phenolics, flavonoids, and photosynthetic pigments are non-enzymatic parameters. Making use of molecular techniques such as reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

It has been found that using Aspergillus fumigatus as a biological biopriming tool can positively impact wheat plants experiencing drought stress. The total biomass of stressed wheat plants that had been bio-primed rose by more than 40% as compared to wheat plants that had not been bio-primed. A. fumigatus biopriming either increased or decreased the amount of enzymatic and non-enzymatic substances on biochemical scales, aside from the noticeable increase in photosynthetic pigment that occurs in plants that have been bio-primed and stressed. Drought-resistant genes show a biopriming influence in gene expression.

CONCLUSIONS

This is the first paper to describe the practicality of a. fumigatus biopriming and its effect on minimizing the degrading effects of drought through water limitation. It suggests the potential applications of arid habitat-adapted endophytes in agricultural systems.

Revealing the seed microbiome: Navigating sequencing tools, microbial assembly, and functions to amplify plant fitness

Microbial communities within seeds play a vital role in transmitting themselves to the next generation of plants. These microorganisms significantly impact seed vigor and early seedling growth, for successful crop establishment. Previous studies reported on seed-associated microbial communities and their influence on processes like dormancy release, germination, and disease protection. Modern sequencing and conventional methods reveal microbial community structures and environmental impacts, these information helps in microbial selection and manipulation. These studies form the foundation for using seed microbiomes to enhance crop resilience and productivity. While existing research has primarily focused on characterizing microbiota in dried mature seeds, a significant gap exists in understanding how these microbial communities assemble during seed development. The review also discusses applying seed-associated microorganisms to improve crops in the context of climate change. However, limited knowledge is available about the microbial assembly pattern on seeds, and their impact on plant growth. The review provides insight into microbial composition, functions, and significance for plant health, particularly regarding growth promotion and pest control.

Fungal Endophytes as Mitigators against Biotic and Abiotic Stresses in Crop Plants

The escalating global food demand driven by a gradually expanding human population necessitates strategies to improve agricultural productivity favorably and mitigate crop yield loss caused by various stressors (biotic and abiotic). Biotic stresses are caused by phytopathogens, pests, and nematodes, along with abiotic stresses like salt, heat, drought, and heavy metals, which pose serious risks to food security and agricultural productivity. Presently, the traditional methods relying on synthetic chemicals have led to ecological damage through unintended impacts on non-target organisms and the emergence of microbes that are resistant to them. Therefore, addressing these challenges is essential for economic, environmental, and public health concerns. The present review supports sustainable alternatives, emphasizing the possible application of fungal endophytes as innovative and eco-friendly tools in plant stress management. Fungal endophytes demonstrate capabilities for managing plants against biotic and abiotic stresses via the direct or indirect enhancement of plants' innate immunity. Moreover, they contribute to elevated photosynthesis rates, stimulate plant growth, facilitate nutrient mineralization, and produce bioactive compounds, hormones, and enzymes, ultimately improving overall productivity and plant stress resistance. In conclusion, harnessing the potentiality of fungal endophytes represents a promising approach toward the sustainability of agricultural practices, offering effective alternative solutions to reduce reliance on chemical treatments and address the challenges posed by biotic and abiotic stresses. This approach ensures long-term food security and promotes environmental health and economic viability in agriculture.

Endophytes Modulate Plant Genes: Present Status and Future Perspectives

Interactions among endophytes and plants are widespread and can vary from neutral or positive or negative. Plants are continually in a functionally dynamic state due to interactions with diverse endophytic microorganisms, which produce various metabolic substances. Through quorum sensing, these substances not only help endophytes to outcompete other host-associated pathogens or microbes but also allow them to overcome the plant immune system. Manifold interactions between endophytic microbiota cause a reflective impact on the host plant functioning and the development of 'endobiomes,' by synthesizing chemicals that fill the gap between host and endophytes. Despite the advances in the field, specific mechanisms for the endophytes' precise methods to modulate plant genome and their effects on host plants remain poorly understood. Deeper genomic exploration can provide a locked away understanding of the competencies of endophytes and their conceivable function in host growth and health. Endophytes also can modify host metabolites, which could manipulate plants' growth, adaptation, and proliferation, and can be a more exciting and puzzling topic that must be properly investigated. The consequence of the interaction of endophytes on the host genome was analyzed as it can help unravel the gray areas of endophytes about which very little or no knowledge exists. This review discusses the recent advances in understanding the future challenges in the emerging research investigating how endosymbionts affect the host's metabolism and gene expression as an effective strategy for imparting resistance to biotic and abiotic challenges.