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RESEARCH PRODUCT

Can LCO and mycorrhiza mitigate the impact of water deficit on pea growth in co-inoculations with rhizobium? A preliminary assessment

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National audience; Water stress is a major factor limiting production of legumes in Europe, but could be mitigated by improving interactions between plant roots and soil microbial communities, including symbiotic rhizobia and arbuscular mycorrhizal fungi. These two microbes produce lipochitooligosaccharide (LCO) signals, which stimulate symbiotic interactions and lateral root formation [1, 2]. While N2-fixation by rhizobia fulfills the plants N requirement [3], mycorrhizal fungi can improve mineral nutrition (P, N, S, K, Zn, Cu…) and water uptake [4- 5]. We have investigated in pea plants grown in interaction with a rhizobium strain, to what extent the negative impact of water deficit could be mitigated by the use of either (i) an exogenous mycorrhizal inoculum or (ii) a selected LCO or (iii) both mycorrhizal inoculum and LCO. Plants were grown in pots or innovative RhizoTubes© on the 4PMI high throughput phenotyping platform equipped with imaging cabinets. Following one week of growth under optimal watering conditions, plants were subjected to a water deficit for three weeks. The experimental setup allowed a precise control of watering and an automatic imaging of shoots and nodulated root systems. Plant shoot and root growth and development traits as well as seed yield components were measured for each treatment. This experiment will provide a better understanding of the putative protective effect of LCO treatment and/or mycorrhizal inoculation against drought stress in nodulated peas and help define optimized plant-LCOsymbiont combinations to increase pea tolerance to abiotic stress.