“We were all rooting for you!” Probing for protein exudates that influence root-substrate adhesion in Arabidopsis thaliana

Abstract

Soil erosion poses a serious threat to global food security; therefore, it is vital that we develop novel crops to reduce this threat. It is widely accepted that plants reduce soil erosion through contributions of both their above and below ground material. However, little is known about the effects of micro- and nano-scale interactions between the root and the soil in regards to limiting soil erosion. Studies are beginning to highlight the importance of micro-scale root properties such as root hairs and nano-scale contributions from exudates in influencing the root-substrate adhesion of plants. Very few studies have touched upon the role of protein exudates and if they may also have a part to play in root-substrate adhesion. Analysis of a proteomics dataset of differential exudate abundance between Arabidopsis thaliana wild type and a root hairless mutant identified four exudate candidates (CYCLASE1, iPGAM1, PELPK1 and XTH23) which I hypothesised to most likely influence root-substrate adhesion. XTH23 was the top candidate identified in my analysis; I also tested XTH8, XTH17 and XTH19, which are in the same XTH protein family. Homozygous mutant lines of these proteins were examined in search for root-substrate adhesion phenotypes using a novel centrifuge assay developed in the lab. Mutants xth23-1 and xth19 showed enhanced root-substrate adhesion relative to the wild type. Thus, protein exudates XTH23 and XTH19 modify root-substrate adhesion. Putative orthologs to the A. thaliana XTH23 were identified in five out of seven top crop species tested: cassava, soybean, tomato, potato and common wheat. XTH23 may therefore be an important target for manipulating root-soil interactions in agricultural crops and potentially limiting soil erosion.

Date of Award	17 Jan 2022
Original language	English
Awarding Institution	University of Bristol
Supervisor	Claire S Grierson (Supervisor) & Emily R Larson (Supervisor)