Abstract
Trehalose plays important roles in plant growth and stress responses and is synthesized from trehalose‐6‐phosphate by trehalose‐6‐phosphate phosphatase (TPP). Here, we show that trehalose and abscisic acid (ABA) have synergistic effects on root growth and stomatal closure. The Arabidopsis thaliana genome contains ten genes encoding TPPs and the expression level of one, TPPE, and trehalose contents increased in response to ABA. In the presence of ABA, the ABA‐responsive transcription factor ABA RESPONSE ELEMENT BINDING FACTOR2 (ABF2) directly binds to the TPPE promoter to activate its expression. Genetic analysis revealed that TPPE acts downstream of ABF2, which is supported by the findings that TPPE expression and trehalose content are reduced in the abf2 mutant and that a mutation in TPPE abolished the ABA‐sensitive root elongation phenotype of 35S:ABF2 plants. Reactive oxygen species (ROS) accumulation in response to ABA failed to occur in tppe mutant plants, suggesting that TPPE is involved in ABA‐controlled root elongation and stomatal movement by inducing ROS accumulation. This study uncovers a new branch of the ABA signaling pathway and provides a molecular basis for the role of trehalose in plant responses to abiotic stress.
Highlights
The non‐reducing disaccharide trehalose is composed of two glucose molecules linked by α,α‐1, 1‐glycoside bond
These results indicate that trehalose and abscisic acid (ABA) have synergistic effects on root elongation and stomatal closure
The expression of ABSCISIC ACID DEFICIENT2 (ABA2) and NINE‐ CIS‐EPOXYCAROTENOID DIOXYGENASE3 (NCED3), key genes in the ABA biosynthesis pathway (Iuchi et al 2001; Endo et al 2008), did not significantly differ in the presence versus absence of trehalose (Figure S1). These results indicate that trehalose does not affect the ABA biosynthesis pathway, and they suggest that trehalose functions downstream of ABA signaling during root elongation and stomatal closure
Summary
The non‐reducing disaccharide trehalose is composed of two glucose molecules linked by α,α‐1, 1‐glycoside bond. Trehalose plays roles in resistance to environmental stresses such as dehydration and heat (Hounsa et al 1998). Trehalose serves as a major source of sugar, participating in growth, development, molting, and metamorphosis (Elbein et al 2003). Trehalose plays an important role in regulating gene expression, tuning plant metabolism, growth, development, and stress responses (Paul et al 2008). Expressing a bacterial or yeast trehalose biosynthesis gene to alter trehalose content significantly affected abiotic stress tolerance in tobacco (Nicotiana tabacum), Arabidopsis thaliana, rice (Oryza sativa), potato (Solanum tuberosum), and other plants (Miranda et al 2007; Kondrak et al 2011; Kondrak et al 2012).
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