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

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.

Plasticity in response to soil texture affects the relationships between a shoot and root trait and responses vary by population

“…These findings suggest that the resulting physical properties of the substrates and source plant population play an important role in the strength of shootroot trait relationships and affect the possibility to derive traits of a plant organ from the traits of another. Dry sand increased root tip production, and this agrees with findings in the literature (Jupp and Newman, 1987;Placido et al, 2020). Because the sand substrate had the lowest moisture content, coupled with comparable shoot height with loam substrate with nearly 60% greater moisture content, this indicates that greater root tip production in sand likely improved water uptake (Sharma and Ghidyal, 1977;Sharp and Davies, 1979) and supported aboveground growth.…”

Small “Nested” Introgressions from Wild Thinopyrum Species, Conferring Effective Resistance to Fusarium Diseases, Positively Impact Durum Wheat Yield Potential

“…As tiller number was unaffected by the G × I interaction ( Table 4 ), the higher GYS under drought-prone conditions likely allowed R69-9/R112+ recombinant to maintain total plant yield (GY) at high levels, possibly through more efficient assimilate transfer to grains. Thinopyrum species are adapted and even cultivated in harsh and dry environments [ 55 ], and numerous genes/QTL that improve adaptation to environmental stresses, including drought, have been identified in the species themselves (e.g., [ 56 ]) and in their introgression products into wheat (e.g., [ 57 , 58 , 59 , 60 ]). Nevertheless, to confirm the present results and to describe the nature of the suggested better adaptability, further research and field trials across diverse environments are underway.…”

Wheat root systems as a breeding target for climate resilience

“…Chromosomally engineered durum wheat Thinopyrum ponticum recombinant lines tested in a range of contrasting rain-fed environments showed associated effects between seminal root angle and yield (Kuzmanović et al 2018). By exploring root gene transcription in lines contrasting for this introgression, as well as RNAi gene silencing in bread wheat, the gene LATERAL ROOT DENSITY (LRD) was identified as a repressor of root growth under drought conditions and was proposed to control the deeper rooting phenotype under drought conditions conferred by the Agropyron introgression (Placido et al 2020).…”