Fundamental Controls on Plant Root Exudation Under Climate Change

Abstract

Root exudates are increasingly recognised as a key driver of global carbon cycling and ecosystem function. The analysis of root exudates has traditionally taken place on plants that have been grown in hydroponic systems. However, this environment lacks the highly complex and heterogeneous structure, as well as the microbial community, of soil, and collected root exudates might not be meaningful for predicting their function in a soil environment. There is no general consensus on the best way to collect and analyse root exudates, because of methodological issues with plant growth in both hydroponics and soil. Here we show that a hybrid system of soil-based growth with a hydroponic root repair stage causes consistent differences in 1) root traits, 2) root metabolites, and 3) root exudates, when compared with growth in purely hydroponic systems. We additionally show that this method was capable of detecting a distinct metabolomic signature of drought in whole root tissue and in exudates, even after a hydroponic root-recovery period, validating its use for abiotic stress-type environments. This work also advances the use of Fourier Transform Infra-Red spectroscopy as an appropriate and inexpensive high-throughput method for analysis of exudates as a sample type, particularly when combined with mass spectrometric techniques. Our results demonstrate the utility of infra-red spectroscopy in investigations of exudates and soil chemistry and show that this inexpensive technique can offer an insight into belowground systems. Future work concerning rhizosphere responses to abiotic stresses should focus on soil-based systems and should consider spectroscopic analyses as an alternative or additive to spectrometric techniques.

Date of Award	6 Oct 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Giles Johnson (Main Supervisor), Patrick Gallois (Co Supervisor), Royston Goodacre (Co Supervisor) & Franciska De Vries (Co Supervisor)