Metarhizium anisopliae (MetA1) seed priming improves photosynthesis, growth, plant defense and yield of wheat under drought stress

Drought stress mitigation by endophytic microorganisms has the potential to enhance crop resilience. This research investigated the effects of M. anisopliae isolate MetA1 (MA) on drought tolerance in wheat plants by evaluating physiological, morphological, biochemical, and yield characteristics of two wheat genotypes, one being drought-susceptible (BR20) and another having drought withstanding capacities (BR28) in a pot experiment under moderate and severe drought conditions. Under drought conditions, root colonization by M. anisopliae ranged from 33.33 to 66.67%. M. anisopliae treated plants increased the plant photosynthetic capacities by increasing photosynthetic pigments, Phi2, gH⁺, vH⁺, LEF, ECSt, leaf thickness and decreasing PhiNO, PhiNPQ, NPQt and leaf angle mostly for both genotypes, which contributed significant improvement of plant biomass in drought conditions. Exceptionally, the seed primed with M. anisopliae noticeably improved root length (by up to 17.6%) under drought conditions corroborated with the plant's drought mitigating approach. The stress induced malondialdehyde and hydrogen peroxide levels were dropped significantly by improving enzymatic antioxidants, such as peroxidase, ascorbate peroxidase, superoxide dismutase, catalase, and glutathione S-transferase in both M. anisopliae -primed genotypes. Also, proline content increased in the leaves of M. anisopliae treated plant which indicates better osmotic adjustment. Finally, M. anisopliae seed priming increased yield and yield characteristics of both genotypes in drought as well as non-drought situations with 1000-grain weight improving by up to 41.77% under severe drought. The study proposes a further investigation of M. anisopliae's effect in field settings and its applicability to other crops. Collectively, these findings emphasize the practical potential of M. anisopliae seed priming in boosting wheat production under water-limited circumstances, presenting a realistic technique for minimizing the effect of drought on global food security.