Grape ASR Regulates Glucose Transport, Metabolism and Signaling

Abstract

To decipher the mediator role of the grape Abscisic acid, Stress, Ripening (ASR) protein, VvMSA, in the pathways of glucose signaling through the regulation of its target, the promoter of hexose transporter VvHT1, we overexpressed and repressed VvMSA in embryogenic and non-embryogenic grapevine cells. The embryogenic cells with organized cell proliferation were chosen as an appropriate model for high sensitivity to the glucose signal, due to their very low intracellular glucose content and low glycolysis flux. In contrast, the non-embryogenic cells displaying anarchic cell proliferation, supported by high glycolysis flux and a partial switch to fermentation, appeared particularly sensitive to inhibitors of glucose metabolism. By using different glucose analogs to discriminate between distinct pathways of glucose signal transduction, we revealed VvMSA positioning as a transcriptional regulator of the glucose transporter gene VvHT1 in glycolysis-dependent glucose signaling. The effects of both the overexpression and repression of VvMSA on glucose transport and metabolism via glycolysis were analyzed, and the results demonstrated its role as a mediator in the interplay of glucose metabolism, transport and signaling. The overexpression of VvMSA in the Arabidopsis mutant abi8 provided evidence for its partial functional complementation by improving glucose absorption activity.

Identification of the Abscisic Acid-, Stress-, and Ripening-Induced (ASR) Family Involved in the Adaptation of Tetragonia tetragonoides (Pall.) Kuntze to Saline–Alkaline and Drought Habitats

“…As stress-inducible genes, most ASRs have been cloned and reported in some crops [10][11][12]16,17,21,23,[26][27][28][29][30][31][32][33][34] and several wild plants [13][14][15]22,24,25], mainly being involved in salt, drought, cold, and oxidative stress, disease resistance, ABA responses, and other developmental or metabolism processes. However, there is little information on ASR genes in halophytes, and only specific ASR members have been characterized in special-habitat plants, including halophytes [13,14,18,19,36].…”

“…ASRs belong to small hydrophilic proteins and are often encoded by small gene families. Since the first ASR gene was identified in tomato (Solanum lycopersicum L.) [7], an increasing number of ASR genes have been identified and cloned from different dicotyledons and monocotyledons [8][9][10][11][12]. Interestingly, no ASR gene members exist in the Brassicaceae family, including the model plant Arabidopsis thaliana.…”

Special Issue “Sugar Transport, Metabolism and Signaling in Plants”

“…To gain an initial understanding of the position of VvMSA in glucose signaling, ref. [ 16 ] used a comprehensive approach including pharmacological, biochemical, molecular and genetic strategies in VvMSA gain- and loss-of-function embryogenic and non-embryogenic grapevine cells. The choice of these two models is crucial for discriminating between glucose-sensitive signaling and glucose-metabolism-dependent processes.…”