Multilevel analysis towards drought tolerance in Legumes

One of the most crucial functions of plant cells is their ability to respond to alterations in their environment. Understanding the connections between initial responses and the downstream events that constitute successful adjustment to its fluctuating environment is one of the challenges of plant biology research. Investigations on transcript level are the most common studies so far. Besides transcript analyses, new technologies based on mass spectrometry allow for the comprehensive study on metabolite and protein level. Past studies have focussed on different stresses such as temperature, drought or salt using various plants and technologies. All these data have improved the understanding on the complexity of the plant response depending on the intensity and duration of homeostatic perturbation. However, due to the diversity of the research data and experimental conditions a comparison and integration is difficult or even impossible. Thus to gain better insights and to be able to visualise the complexity of the plant respond, integrative analyses combining different technologies and standardised cultivation conditions are becoming necessary. Legumes are major sources of vegetable protein and indispensable for sustainable agriculture due to their ability to fix atmospheric nitrogen via their symbiosis with soil rhizobia. These bacteria colonize legume roots in specialized organs called nodules. However, a full understanding of the interactive regulatory mechanisms between plant and bacteroids towards increased stress tolerance is not accomplished so far. To contribute to a deeper understanding of responses of legumes to major constraints, the proposed project aims at employing comparative systems biology. Supported by bioinformatic modelling strategies, novel metabolic and proteomic key mechanisms that may serve as regulatory targets for improving stress-tolerance in legumes will be identify.

Within this FWF funded Project, multilevel analyses and technological developments allowed the research group around Stefanie Wienkoop to describe so far unknown molecular mechanisms. In legumes (e.g. pea and bean) this mechanisms play fundamental roles for improved drought stress tolerance. Legumes are able to establish beneficial interactions (symbiosis) with rhizobia. The scientists found that this plant-rhizobia interaction plays a key role within stress response. Leaf senescence, induced by water deficiency, was decelerated through symbiotic interaction. This slowed senescence process, also called stay-green effect has also been observed in agriculture, but is not fully understood until now.Drought stress is a major cause for crop loss and thus plays an important role in the course of climate change. Legumes are principal source of protein nutrition for human. The directed application of specific rhizobia as a substitute for nitrogen fertilization may reduce costs in addition to improved drought stress tolerance.Besides a symbiotic priming effect that changed the molecular background of the plants (similar to inoculation), the team found some putative key molecules that may be relevant for future application in biotechnology towards improved stress tolerance. These insights may also be transferable to other plant families. One of those key molecules could already be evaluated within this project.