A Diaporthe fungal endophyte from a wild grass improves growth and salinity tolerance of tritordeum and perennial ryegrass

16 páginas, 6 figuras, 1 tablaSome microbiome components can provide functions that extend the capabilities of plants, increasing the environmental adaptability and performance of holobionts. Festuca rubra subsp. pruinosa is a perennial grass adapted to rocky sea cliffs, where soil and nutrients are very limited, and exposure to salinity is continuous. This study aimed to investigate if a Diaporthe fungal endophyte belonging to the core microbiome of Festuca rubra roots could improve the performance of two agricultural grasses. In a greenhouse experiment, plants of tritordeum (Triticum durum x Hordeum chilense) and perennial ryegrass (Lolium perenne) were inoculated with Diaporthe strain EB4 and subjected to two salinity conditions (0 and 200 mM NaCl). Biomass production, mineral elements, proline, hormone profiles, antioxidant capacity, and total phenolic compounds were examined in plants, and fungal functions potentially related to the promotion of plant growth were determined. The inoculation with Diaporthe promoted plant growth of both grasses, increasing leaf biomass (84% in tritordeum and 29% in perennial ryegrass), root biomass, nutrient content (N, Ca, Mg, and Fe), and the production of indole 3-acetic acid, regardless of the salinity treatment. Improved growth and nutrient uptake might occur because Diaporthe produces several extracellular enzymes capable of recycling organic nutrient pools. In addition, the fungus produced indole 3-acetic acid in vitro and modulated the production of this phytohormone in the plant. Under salinity, the activity of Diaporthe ameliorated the stress, increasing proline, nutrient uptake in roots, gibberellins, and indole 3-acetic acid, which in turn results into improved growth. Thus, this fungus can transfer to alternative hosts some advantages useful at its original habitat.This research was supported by grant AGL2016-76035-C21R funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe,” grant PID2019-109133RB-I00 funded by MCIN/AEI/10.13039/501100011033; by the European Union’s H2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 676480; and by project “CLU2019-05—IRNASA/CSIC Unit of Excellence” funded by the Junta de Castilla y León and co-financed by EU (ERDF “Europe drives our growth”). RT was supported by grant FJC2018-03857-I funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your Future.Peer reviewe