Agropolis foundation: Determining root mucilage exudation as a key adaptive trait mitigating drought impacts 

Prof. Michaela Dippold, Dr. Callum C. Banfield, Dr. Meseret Tesema Terfa

Intensified and frequent drought has severely increased the scarcity of water limitation. This situation has posed greater risk in crop production worldwide and more so in sub-Saharan region. One of the strategies is to understand and exploit the below ground (root and rhizosphere) traits such as root mucilage and the dynamic interaction with their microbial environment. Mucilage, a polymeric gel exuded at the root tip and capable of absorbing large volumes of water, is a strategy that plants deploy to dynamically alter the gradients in water potential at the root–soil interface. The premise is that mucilage keeps the rhizosphere wet, connected to the root surface and hydraulically well conductive, especially in drying soil. The quantity and composition of the mucilage can in turn be affected by the soil moisture conditions. Furthermore, the soil moisture condition affects the microbial activity and physiology in the rhizosphere. Conversely, it is shown that mucilage maintain moisture around the rhizosphere that affects the root-microbial interaction and thereby the microbial community such as arbuscular mycorrhizal fungi (AMF). The interaction between the soil moisture condition, mucilage and the soil AMF are postulated to have impact on cycling of soil organic matter especially the dissolvable organic matter. Hence, elucidating and disentangling the complex dynamics between these important key factors is paramount in the understanding of the rhizosphere.

Thus, the objectives of this project are: 1) to characterize the sugar monomer composition of mucilage extracted from root tips and tropical soils on which Barley and Sorghum varieties are grown under different soil moisture conditions; 2) to characterize AMF communities in the rhizosphere and specifically in the mucilage-covered biofilm area of the rhizosphere; 3) to analyse the extractable organic matter using untargeted soil metabolomics method from these conditions.