Why Is the Correct Selection of Strains Important? The Case of Wheat Endophytic Strains of and .

The search for endophytic fungi in the roots of healthy wheat plants from a non-irrigation field trial allowed us to select 4 out of a total of 54 cultivable isolates belonging to the genus , identified as T136 and T139, T137, and T138. In vitro assays against the phytopathogenic fungus showed that the strains had the highest biocontrol potential and that T136 exhibited the highest cellulase and chitinase activities. Production patterns of eight phytohormones varied among the strains. All four, when applied alone or in combination, colonized roots of other wheat cultivars and promoted seed germination, tillering, and plant growth under optimal irrigation conditions in the greenhouse. Apart from T136, the endophytic strains showed plant protection capacity against drought as they activated the antioxidant enzyme machinery of the wheat plants. However, T137 gave the best plant size and spike weight performance in water-stressed plants at the end of the crop. This trait correlated with significantly increased production of indole acetic acid and abscisic acid and increased 1-aminocyclopropane-1-carboxylic acid deaminase activity by T137. This study shows the potential of endophytes and that their success in agricultural systems requires careful selection of suitable strains.