Overexpression of the vascular brassinosteroid receptor BRL3 confers drought resistance without penalizing plant growth

Abstract

Drought represents a major threat to food security. Mechanistic data describing plant responses to drought have been studied extensively and genes conferring drought resistance have been introduced into crop plants. However, plants with enhanced drought resistance usually display lower growth, highlighting the need for strategies to uncouple drought resistance from growth. Here, we show that overexpression of BRL3, a vascular-enriched member of the brassinosteroid receptor family, can confer drought stress tolerance in Arabidopsis. Whereas loss-of-function mutations in the ubiquitously expressed BRI1 receptor leads to drought resistance at the expense of growth, overexpression of BRL3 receptor confers drought tolerance without penalizing overall growth. Systematic analyses reveal that upon drought stress, increased BRL3 triggers the accumulation of osmoprotectant metabolites including proline and sugars.Transcriptomic analysis suggests that this results from differential expression of genes in the vascular tissues. Altogether, this data suggests that manipulating BRL3 expression could be used to engineer drought tolerant crops.

Brassinosteroids: Multidimensional Regulators of Plant Growth, Development, and Stress Responses

“…It is becoming increasingly evident that the BR pathway does not represent a linear signaling pathway that operates in isolation, but rather that BRs undergo crosstalk with multiple other hormones and stress responses (Nolan et al, 2017a). Moreover, BR signaling varies among different cells and tissues, which can be manipulated to improve plant growth and stress responses (Fàbregas et al, 2018).…”

“…This appears to be the case for the BR signaling pathway operating through BRI1 to downstream BES1 and BZR1 TFs (Chen et al, 2017;Nolan et al, 2017b;Ye et al, 2017). However, overexpression of the vascular BR receptor BRL3 promotes drought responses without penalizing growth (Fàbregas et al, 2018).…”

“…Overexpression of DREB1A led to increased drought tolerance and growth inhibition, but the growth limitation could be overcome by simultaneous overexpression of DREB1A together with the rice homolog of PIF4 (OsPIL1) in Arabidopsis (Kudo et al, 2016). Along these lines, an elegant study demonstrated that overexpressing the BR receptor gene BRL3 increased plant survival during drought without the growth penalty observed in BR mutants such as the loss-of-function mutant bri1 (Fàbregas et al, 2018). In this case, BRL3 expression was driven by a constitutive promoter, but BRL3 protein primarily accumulates in the vascular tissue of roots, where it promotes the accumulation of osmoprotective metabolites and stress-responsive gene expression (Fàbregas et al, 2018).…”

“…Along these lines, an elegant study demonstrated that overexpressing the BR receptor gene BRL3 increased plant survival during drought without the growth penalty observed in BR mutants such as the loss-of-function mutant bri1 (Fàbregas et al, 2018). In this case, BRL3 expression was driven by a constitutive promoter, but BRL3 protein primarily accumulates in the vascular tissue of roots, where it promotes the accumulation of osmoprotective metabolites and stress-responsive gene expression (Fàbregas et al, 2018). These findings demonstrate that understanding the spatiotemporal complexity of BR signaling holds great promise for engineering stress-resistant crops.…”

A Method for Rapid Analysis of the Root Hydrotropic Response in Arabidopsis Thaliana

“…Recently, it was reported that the apoplastic proton extrusion in root tips is influenced by brassinosteroids (BRs) receptor BR-INSENSITIVE1 (BRI1), which is also crucial for the hydrotropic root response in Arabidopsis [27,28]. Whereas loss-of-function mutations in the ubiquitously expressed BRI1 receptor leads to drought resistance at the expense of growth, overexpression of theBRL3 receptor confers drought tolerance without penalizing overall growth [29]. Hence, BRs signaling links the hydrotropic root response with drought resistance.…”