Fungal endophytes enhance wheat heat and drought tolerance in terms of grain yield and second-generation seed viability

AIMS: We evaluated the impact of fungal endophyte symbiosis on the growth, ecophysiological and reproductive success of wheat exposed to heat and drought. METHODS AND RESULTS: The resistance of pot-grown wheat to heat or drought stress was measured by quantifying efficiency of photosystem II (Fv /Fm), plant height, average seed weight (ASW), total seed weight (TSW), water-use efficiency (WUE) as well as time to 50% germination and percentage germination of second-generation seeds produced under heat stress, drought stress or well-watered conditions. The endophytic fungi tested increased wheat tolerance for drought and heat. Endophyte SMCD 2206 was the most beneficial, followed by SMCD 2210 and 2215. Surprisingly, second-generation seeds produced by drought-stressed wheat colonized by SMCD 2206, 2210 or 2215 had decreased WUE relative to those produced by endophyte-free, drought-stressed plants. However, these seeds germinated more rapidly than those produced by endophyte-free, stressed parental plants. CONCLUSIONS: The tested consortium of endophytes has the potential to improve wheat adaptation to heat and drought. SIGNIFICANCE AND IMPACT OF THE STUDY: The capacity of endophytes to increase wheat tolerance for abiotic stress and to improved germination in endophyte-free second-generation seeds arising from stressed plants could be applicable to agriculture. The mechanisms by which intergenerational endophyte-mediated affects occurs warrant further research.