Influence of the root endophyte <i>Piriformospora indica</i> on the plant water relations, gas exchange and growth of <i>Chenopodium quinoa</i> at limited water availability

Abstract

Abstract This study aimed to evaluate the ability of Piriformospora indica to colonize the root of Chenopodium quinoa and to verify whether this endosymbiont can improve the growth, performance and drought resistance of this species. The study delivered, for the first time, evidence for successful colonization of P. indica in quinoa. Hence, pot experiment was conducted in the greenhouse, where inoculated and non‐inoculated plants were subjected to ample (40%–50% WHC ) and deficit (15%–20% WHC ) irrigation treatments. Drought adversely influenced the plant growth, leading to decline the total plant biomass by 74%. This was linked to an impaired photosynthetic activity (caused by lower g s and C i /C a ratio; stomatal limitation of photosynthesis) and a higher risk of ROS production (enhanced ETR /A gross ratio). P. indica colonization improved quinoa plant growth, with total biomass increased by 8% (controls) and 76% (drought‐stressed plants), confirming the growth‐promoting activity of P. indica . Fungal colonization seems to diminish drought‐induced growth hindrance, likely, through an improved water balance, reflected by the higher leaf ψ w and g s . Additionally, stomatal limitation of photosynthesis was alleviated (indicated by enhanced C i /C a ratio and A net ), so that the threat of oxidative stress was minimized (decreased ETR /A gross ). These results infer that symbiosis with P. indica could negate some of the detrimental effects of drought on quinoa growth, a highly desired feature, in particular at low water availability.