Abstract
Root systems can display variable architectures that contribute to nutrient foraging or to increase the tolerance of abiotic stress conditions. Root tip excision promotes the developmental progression of previously specified lateral root (LR) founder cells, which allows to easily measuring the branching capacity of a given root as regards its genotype and/or growth conditions. Here, we describe the natural variation among 120 Arabidopsis thaliana accessions in root system architecture (RSA) after root tip excision. Wound-induced changes in RSA were associated with 19 genomic loci using genome-wide association mapping. Three candidate loci associated with wound-induced LR formation were investigated. Sequence variation in the hypothetical protein encoded by the At4g01090 gene affected wound-induced LR development and its loss-of-function mutants displayed a reduced number of LRs after root tip excision. Changes in a histidine phosphotransfer protein putatively involved in cytokinin signaling were significantly associated with LR number variation after root tip excision. Our results provide a better understanding of some of the genetic components involved in LR capacity variation among accessions.
Highlights
Strong modulation of root system architecture (RSA) by environmental cues, such as nutrient and water availability has been a well-documented process in Arabidopsis thaliana (Giehl and von Wirén, 2014; Giehl et al, 2014; Robbins and Dinneny, 2015)
To validate our experimental approach (Figure 1A), we studied wound-induced lateral root (LR) formation in Columbia-0 (Col-0) during 7 days
We found a slight variation in primary roots (PRs) length and LR number between the different sowings (Supplementary Figures S2A,B), which might be caused by subtle environmental differences at the growth chamber
Summary
Strong modulation of root system architecture (RSA) by environmental cues, such as nutrient and water availability has been a well-documented process in Arabidopsis thaliana (Giehl and von Wirén, 2014; Giehl et al, 2014; Robbins and Dinneny, 2015). Root tip excision promotes the developmental progression of most pre-branch sites toward LR emergence, providing an accurate measure for LR branching capacity This later approach will allow assessing whether changes in LR pre-patterning have occurred in different genotypes and/or growth conditions (Van Norman et al, 2014). These results are in agreement with the current view that cells at the root tip are capable of integrating information about the local soil environment, tailoring the RSA for optimal nutrient and water uptake or after PR damage (Robbins and Dinneny, 2015)
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