AtRAE1 is involved in degradation of ABA receptor RCAR1 and negatively regulates ABA signalling in Arabidopsis

Abstract

The phytohormone abscisic acid (ABA) plays an important role in regulating plant growth, development, and adaption to various environmental stresses. Regulatory components of ABA receptors (RCARs, also known as PYR/PYLs) sense ABA and initiate ABA signalling through inhibiting the activities of protein phosphatase 2C in Arabidopsis. However, the way in which ABA receptors are regulated is not well known. A DWD protein AtRAE1 (for RNA export factor 1 in Arabidopsis), which may act as a substrate receptor of CUL4-DDB1 E3 ligase, is an interacting partner of RCAR1/PYL9. The physical interaction between RCAR1 and AtRAE1 is confirmed in vitro and in vivo. Overexpression of AtRAE1 in Arabidopsis causes reduced sensitivity of plants to ABA, whereas suppression of AtRAE1 causes increased sensitivity to ABA. Analysis of protein stability demonstrates that RCAR1 is ubiquitinated and degraded in plant cells and AtRAE1 regulates the degradation speed of RCAR1. Our findings indicate that AtRAE1 likely participates in ABA signalling through regulating the degradation of ABA receptor RCAR1.

ABA Receptor Subfamily III Enhances Abscisic Acid Sensitivity and Improves the Drought Tolerance of Arabidopsis

“…For the stomatal aperture measurements, 4-week-old seedlings were put in the darkness for 24 h the stomata to close. Then, epidermal strips of the rosette leaves were peeled and immersed in the opening buffer (10 mM MES-KOH (pH 6.15), 10 mM KCl, and 50 μM CaCl 2 with or without 30 μM ABA) for 3 h exposed to continue light [ 20 , 33 ]. The stomatal apertures were examined and photographed with a fluorescence microscope (DMI6000B, Leica, Wetzlar, Germany).…”

“…The single rcar3 (pyl8) mutant showed reduced sensitivity to the ABA-mediated root length inhibition [ 8 ], and the interaction of PLY8 and MYB77 promoted the lateral root growth independently of the core ABA-RCAR-PP2C signaling pathway to augment auxin signaling [ 16 ]. On the other hand, RCARs interact with ubiquitin ligases to attenuate ABA signaling, such as DDA1 allowing the ubiquitination of PYL8 [ 17 ], RSL1 targeting PYL4 [ 18 ], F-box E3 ligase RIFP1 mediating the RCAR3 stability [ 19 ], and AtRAE1 being involved in the degradation of RCAR1 [ 20 ]. In Arabidopsis , RCARs function show diversely and redundantly in the ABA signaling and drought-stress pathway [ 7 , 9 ], while the function is unknown until now.…”

Overexpression of the Selective Autophagy Cargo Receptor NBR1 Modifies Plant Response to Sulfur Deficit

“…Hub2 and hub3 have WD40 domains and are part of the nuclear pore complex (NPC). Interestingly, Hub 3 (RAE1; At1g80670) is a component of a nuclear pore [46], but it is also involved in proteolytic protein degradation controlling the level of ABA receptor RCAR1 and negative regulation of ABA signaling [47]. Hub4 (RPT2a, At4g29040) is AAA type ATPase of the 26S proteasome subunit which, among its other roles, interacts with transit peptides of chloroplast proteins [35]; while hub 5 (GRF1, At4g09000) is a member of a large family of GRFs (general regulatory factors, 14-3-3 family), which are involved in protein-protein interactions serving as adapters, activators, and repressors in diverse cellular processes (for recent reviews see [48][49][50]).…”

Abscisic acid‐dependent histone demethylation during postgermination growth arrest in Arabidopsis

“…Seed dormancy and postgermination growth arrest are critical adaptations that allow plants to survive unfavourable conditions (Bentsink & Koornneef, ; Bewley, ; Li et al, ; Lopez‐Molina, Mongrand, & Chua, ). Before germination, seeds contain carbohydrates, proteins, lipids, and phosphates as energy sources and remain in a metabolically quiescent and desiccation‐tolerant state (Bentsink & Koornneef, ).…”