Legume herbs tend to be more resistant to water stress under field conditions than many other herbaceous species, including most grasses. This renders them a key component of pollinator nutrition in the dry season. Moreover, likely due to symbiotic competence, they play an important role in nutrient-poor ecosystems, and are highly competitive in nitrogen-limited habitats in particular.
The molecular basis underlying these phenomena is not fully understood. In particular, the interplay of water and nitrogen deficiency and their combined effect on the formation of bacterial (nodulation) and fungal (arbuscular mycorrhiza) root symbiosis remains to be understood. Vice versa, it is unclear whether and in what way symbiotic activity is involved in providing physiological protection to water stress. In the face of changing climatic conditions and an expected increase in the duration and intensity of drought periods in many ecosystems, an understanding of the molecular basis of plant adaptive potential to water stress is in urgent demand. We combine laboratory and field experiments using ecotype as well as mutant line collections to unravel the genetic framework determining legume performance under extreme water and nutrient regimes.