Fungal endophytes promote wheat growth (PBW-343) and enhance salt tolerance through improvement of ascorbate glutathione cycle and gene expression

Wheat (Triticum aestivum L.) faces considerable challenges in growth and productivity due to soil salinity, a major constraint to agricultural success. This study investigated the potential of fungal endophytes to enhance wheat growth and improve salt tolerance by influencing the ascorbate-glutathione cycle and gene expression. To address this study, A greenhouse experiment was conducted using saline soil (100 mM NaCl) conditions, with wheat plants inoculated with selected fungal endophytes such as Cladosporium parahalotolerant and Aspergillus medius isolated from salt-tolerant wheat genotypes (KRL-210, KRL-213 and KRL-19) in our previous study. These endophytes were used individually and in combination with each other on the reactive oxygen species (ROS) scavenging and antioxidant functions in plants under salt stress. To do so, a 16-days old wheat (PBW-343) seedlings were subjected to 100 mM NaCl in present and absence of the fungal endophytes. The results revealed significant reduction in sugar, protein, chlorophyll, carotenoid content and chlorophyll fluorescence (Fv/Fm) of the plants lacking endophytes. Combinatory applications with two fungal endophytes (C. parahalotolerant and A. medius) significantly improved the above-mentioned parameters compared to non-inoculated control under salt stress. H₂O_2, O₂^- and lipid peroxidation level were significantly reduced in the plants inoculated with fungal endophytes. Salt stress significantly increased activities of ascorbate peroxidase (APX) and superoxide dismutase (SOD) and decreased activities of glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR). Fungal endophytes inoculated salt stressed seedlings enhanced the above-mentioned indicators as compared to the salt-stressed plants without fungal endophytes, as well as in the ratios of reduced ascorbate/dehydroascorbic acid (AsA/DHA) and reduced glutathione/oxidized glutathione (GSH/GSSG). Overall, fungal endophytes inoculation improved salt tolerance and reduced the accumulation of ROS by increasing their scavenging via improving the redox state of ascorbate and glutathione and promotion of antioxidant enzymes activity. To elucidate the molecular mechanisms behind these observed benefits, gene expression analysis was performed on key genes such as APX, SOD, GR, DHAR and MDHAR gene(s) involved in salt tolerance and antioxidant defense pathways. The study found that the expression levels of several genes associated with the ascorbate-glutathione cycle were upregulated in the endophyte-inoculated plants, indicating a more efficient antioxidant system capable of scavenging reactive oxygen species.

Audience Take Away Notes:

• Insights from this research can be used to develop new products, such as biofertilizers and biopesticides, that leverage fungal endophytes
• Companies can explore new markets by developing crops that are more resilient to environmental stresses like salinity
• The integration of fungal endophytes into wheat cultivation, particularly PBW-343, offers a multitude of benefits ranging from improved growth and stress tolerance to economic and environmental gains. These endophytes enhance the ascorbate-glutathione cycle and regulate gene expression, providing a natural and sustainable approach to boost wheat productivity and resilience
• This research could be used by other faculty to expand their own research or teaching