Integrated modulation of redox homeostasis and water relations by a habitat-adapted fungal endophyte confers tolerance to physiological drought in tomato

Aishwarya G; Abhishek R R; Jayalakshmi K T; NATARAJA N KARABA

doi:10.56093/ijas.v96i11.176438

Authors

Aishwarya G Department of Crop Physiology, College of Agriculture, UAS, GKVK, Bengaluru - 560065
Abhishek R R Department of Crop Physiology, College of Agriculture, UAS, GKVK, Bengaluru - 560065
Jayalakshmi K T Department of Crop Physiology, College of Agriculture, UAS, GKVK, Bengaluru - 560065
NATARAJA N KARABA Department of Crop Physiology, College of Agriculture, UAS, GKVK, Bengaluru - 560065

https://doi.org/10.56093/ijas.v96i11.176438

Keywords:

Antioxidant enzymes, Cellular level tolerance, Osmotic adjustment, Habitat-adapted endophyte, Reactive oxygen species

Abstract

Drought stress is a major constraint to sustainable tomato production, primarily due to oxidative damage and disrupted water relations. This study evaluated the role of habitat-adapted endophyte Fusarium equiseti (SF 5) in mitigating polyethylene glycol (PEG)-induced physiological drought stress in tomato seedlings. SF 5 colonization significantly enhanced plant height (37.5 %) and biomass (31.4 %) under water-deficit conditions, while reducing reactive oxygen species (ROS) accumulation and membrane lipid peroxidation. Endophyte-colonized plants maintained higher relative water content and enhanced osmotic adjustment through increased proline accumulation. Further, activities of key antioxidant enzymes, superoxide dismutase and catalase, were increased, accompanied by upregulation of SlSOD1 (1.5-fold) and SlCAT1 (1.3-fold) compared with non-colonized stressed plants. These coordinated physiological, biochemical, and molecular responses indicate that SF 5 promotes cellular-level tolerance through integrated regulation of redox balance, osmotic adjustment, and regulation of plant water relations during drought stress. The findings highlight the potential of habitat-adapted fungal endophytes as eco-friendly bio-inoculants for environmentally sustainable and climate-resilient agricultural systems.

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