Changes in root-exudate-induced respiration reveal a novel mechanism through which drought affects ecosystem carbon cycling.

Root exudates play an important role in ecosystem response to climate change, but the functional consequences of drought-induced changes in the quality of root exudates are unknown. Here, we addressed this knowledge gap in a unique experimental approach. We subjected two common grassland species that differ widely in their growth strategies and root systems, the grass Holcus lanatus and the forb Rumex acetosa, to 2 wk of drought. We collected root exudates and soils at the end of the drought and after 2 wk of recovery and readded all root exudates to all soils in a fully reciprocal set-up to measure root-exudate-induced respiration. We found that soil treatment was unimportant for determining root-exudate-induced respiration. By contrast, root exudates collected from plants that had experienced drought clearly triggered more soil respiration than exudates from undroughted plants. Importantly, this increased respiration compensated for the lower rates of root exudation in droughted plants. Our findings reveal a novel mechanism through which drought can continue to affect ecosystem carbon cycling, and a potential plant strategy to facilitate regrowth through stimulating microbial activity. These findings have important implications for understanding plant and ecosystem response to drought.

Chia seed mucilage - a vegan thickener: isolation, tailoring viscoelasticity and rehydration.

Chia seeds and their mucilage gels provide a nutritionally and functionally promising ingredient for the food and pharmaceutical industry. Application and utilization of the gel remain limited due to the tightly adhesion of the mucilage to the seeds, which affects the organoleptic properties, control of concentration and structuring possibilities. To exploit the full potential of chia mucilage gels as a functional ingredient calls for separation and purification of the gel. Herein, the gel was extracted by centrifugation and characterized rheologically and microscopically to link the viscoelastic properties to the structural properties. Subsequently, the gel was dried employing three different methods for facilitated storage and prolonged shelf life. The dried gels were readily soluble and its viscoelastic properties were fully regenerated upon rehydration demonstrating its potential to envisage industrial applications. The viscoelastic chia mucilage demonstrated shear-thinning behavior with complete relaxation upon stress removal. The gel's elasticity was enhanced with increasing mucilage concentration resulting in a highly tunable system. The extractable and rehydratable functional chia gel is a viable candidate as additive for the development of products requiring specific viscoelastic properties. Addition of the gel enhances the nutritional profile without interfering with the organoleptic properties.