Improvement of water stress tolerance of plants by endophytic fungus Leptosphaeria sp. strain T-2

Abstract

Endophytic fungi are a microbe that doesn’t show the symptom even though it can infect to the host plant. They sometimes confer some function such as plant growth promoting (PGP) effects and environmental stress tolerance on the host plant. If it will be possible to use endophytes having useful ability in agriculture, they can be strong tool for sustainable agriculture under environmental stress conditions.

Leptosphaeria sp. T-2 was isolated from barley root grown at Toyama prefecture (Japan) in 2018. This fungus showed PGP effect on host plant, and this effect need direct fungal infection to host plant. Because, strain T-2 showed the plant growth promotion only when strain T-2 infected to the plant, whereas it didn’t express the plant growth promotion when the culture broth of strain T-2 was applied. In addition, pot experiment showed that fresh weight of harvested plant was significantly heavier in the plant with strain T-2 than that without strain T-2. There was no significantly difference in dry weight of harvested plant, indicating that strain T-2 might enhance the water uptake of host plant. In order to reveal this fungal ability, strain T-2 grew on the MS medium with water stress using PEG8000. The results indicated host plant with strain T-2 survived even in the high water stress conditions compared with control (Figure 1), indicating that the strain T-2 improved the water uptake capacity of host plant. Moreover, when strain T-2 grew on the MS medium added NaCl as salt stress, the host plant with strain T-2 obviously grew even in the salinity condition. Conclusively, this endophytic fungus, Leptosphaeria sp. T-2, was infected plant roots without any symptoms and improved the host plant growth. Moreover, strain T-2 could confer the drought and salinity stress tolerant to host plant. Further studies are contemplated to obtain a more information about the mechanisms for environmental stress remains unknown.