Fungal endophytes improve wheat seed germination under heat and drought stress

Seed germination is a critical life stage for plants survival and timely seedling establishment especially in stressful environments. We hypothesized that fungal endophytes would improve wheat seed germination under heat and drought stress. The hydrothermal time (HTT) model of germination is a conceptual model useful for predicting the timing and energy of germination (EG) under a given set of conditions. The HTT and EG are applied, for the first time, to determine if one or more compatible endophytic fungi enhance heat or drought tolerance in wheat. Fungal endophytes tested dramatically increased the percent of germination, improved EG and HTT values, and diminished wheat susceptibility to heat and drought as measured by fresh weight of seedlings. When colonized by the most effective fungal endophyte, the values of the parameters tested in wheat seeds exposed to heat stress resembled those of unstressed seeds.