The LATERAL ROOT DENSITY gene regulates root growth during water stress in wheat

Dante F. Placido, University of Nebraska - Lincoln
Jaspreet Sandhu, University of Nebraska-Lincoln
Shirley Sato, University of Nebraska - Lincoln
Natalya Nersesian, University of Nebraska-Lincoln
Truyen Quach, University of Nebraska-Lincoln
Thomas Clemente, University of Nebraska - Lincoln
Paul E. Staswick, University of Nebraska - Lincoln
Harkamal Walia, University of Nebraska-Lincoln

Document Type Article

Copyright 2020 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License

Abstract

Drought stress is the major limiting factor in agriculture. Wheat, which is the most widely grown crop in the world, is predominantly cultivated in drought-prone rainfed environments. Since roots play a critical role in water uptake, root response to water limitations is an important component for enhancing wheat adaptation. In an effort to discover novel genetic sources for improving wheat adaptation, we characterized a wheat translocation line with a chromosomal segment from Agropyron elongatum, a wild relative of wheat, which unlike common wheat maintains root growth under limited-water conditions. By exploring the root transcriptome data, we found that reduced transcript level of LATERAL ROOT DENSITY (LRD) gene under limited water in the Agropyron translocation line confers it the ability to maintain root growth. The Agropyron allele of LRD is down-regulated in response to water limitation in contrast with the wheat LRD allele, which is up-regulated by water deficit stress. Suppression of LRD expression in wheat RNAi plants confers the ability to maintain root growth under water limitation. We show that exogenous gibberellic acid (GA) promotes lateral root growth and present evidence for the role of GA in mediating the differential regulation of LRD between the common wheat and the Agropyron alleles under water stress. Suppression of LRD also had a positive pleiotropic effect on grain size and number under optimal growth conditions. Collectively, our findings suggest that LRD can be potentially useful for improving wheat response to water stress and altering yield components.