Contribution of Root Hair Development to Sulfate Uptake in Arabidopsis

Root hairs often contribute to nutrient uptake from environments, but the contribution varies among nutrients. In Arabidopsis, two high-affinity sulfate transporters, SULTR1;1 and SULTR1;2, are responsible for sulfate uptake by roots. Their increased expression under sulfur deficiency (？S) stimulates sulfate uptake. Inspired by the higher and lower expression, respectively, of SULTR1;1 in mutants with more ( werwolf [ wer]) and fewer ( caprice [ cpc]) root hairs, we examined the contribution of root hairs to sulfate uptake. Sulfate uptake rates were similar among plant lines under both sulfur sufficiency (+S) and ？S. Under ？S, the expression of SULTR1;1 and SULTR1;2 was negatively correlated with the number of root hairs. These results suggest that both ？S-induced SULTR expression and sulfate uptake rates were independent of the number of root hairs. In addition, we observed (1) a negative correlation between primary root lengths and number of root hairs and (2) a greater number of root hairs under ？S than under +S. These observations suggested that under both +S and ？S, sulfate uptake was influenced by the root biomass rather than the number of root hairs. View Full-Tex