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Exploiting beneficial associations with chickpea: the role of non-rhizobial endophytic bacteria in the rhizobia-legume symbiosis

Posted by | February 21, 2021

Principal investigators: Clarisse Brígido

Associated with: University of Évora, Portugal

Project Summary: 

The growing concern on environment and food security demands that increases in crop production must be achieved through sustainable agricultural practices. In this sense, the use of legumes is unparalleled due to their ability to establish symbiosis with rhizobia, which are soil bacteria responsible for the fixation of atmospheric nitrogen. However, the processes involved in this symbiotic association are very sensitive to several environmental stresses, conditioning the success of this symbiosis and limiting the legume crop yields.

Besides rhizobia, other beneficial endophytic bacteria able to colonize plant roots, have gained special attention due to their great potential as plant growth-promoting bacteria for use in agriculture. Non-rhizobial endophytic bacteria (NREB) may possess one or more plant growth-promoting traits (PGPT). The use of consortia containing rhizobia and NREB showed benefits for nodulation and nitrogen fixation efficiency, but the combination of various organisms not always results in benefit to the legume. These results clearly indicate that further studies on the mechanisms involved in the interactions between multiple endosymbionts are needed.

This project aims to investigate the interplays among multiple legume endosymbionts and their combined impacts on legume growth. Therefore, the involvement of PGPT and other mechanisms in the interactions between NREB-legume and NREB-rhizobia are being investigated using mesorhizobia-chickpea as the symbiotic plant-rhizobia model.

The research team is multidisciplinary and counts several soil microbiologists with know-how on rhizobia and other beneficial bacteria, arbuscular mycorrhizal fungi as well as an agronomist with experience on manganese toxicity and conservation agriculture. The research team also has the contribution of 2 external consultants: Bernard R. Glick from University of Waterloo, Canada  with recognized expertise on the use and characterization of bacteria that promote plant growth for agricultural purposes, and Pedro F. Mateos from University of Salamanca, Spain, which has high experience and knowledge in the study of plant-microbe interactions. The expected results will contribute to understand the mechanisms responsible for synergistic outcomes which may help to develop systems that improve legume growth by optimizing the legume-bacteria associations, and to define criteria to select adequate NREB consortia. In addition, we expect to highlight the knowledge on the interactions between multiple NREB and rhizobia.