Adaptive mechanisms of tall wheatgrass to salinity and alkalinity stress

Tall wheatgrass -Elymus elongatus (Host) Runemark- has long been used for forage production in temperate areas where salinity, alkalinity, waterlogging, or water scarcity hinder growth of other fodder species, and has a broad history of being included in revegetation programs of saline land and in wheat breeding programs. Despite its renown as a suitable species for unfavourable soil environments, the physiological mechanisms underlying its tolerance to abiotic stresses are scattered across the literature and this precludes answering the question that has motivated this review: how does tall wheatgrass endure inhospitable soil environments? The review starts with an outline of saline, alkaline and saline-alkaline soils, and their associated waterlogging or water scarcity events. This is followed by a delineation of the physiological mechanisms responsible for plant tolerance to such soils, with an emphasis on the mechanisms associated with tall wheatgrass. Briefly outlined, tall wheatgrass has shown evidence of possessing mechanisms to allow the continuity of water influx -where salinity or drought leads to reduced water availability-, strategies to avoid ion toxicity and to acquire essential nutrients, and ability to cope with high pH levels, waterlogging and excess reactive oxygen species produced as a consequence of stress. Seeking the answer to this inquiry, this review also contributes to the understanding of forage production and quality in these fragile soil environments.