The Protein Kinase SnRK2.6 Mediates the Regulation of Sucrose Metabolism and Plant Growth in Arabidopsis  

Abstract

In higher plants, three subfamilies of sucrose nonfermenting-1 (Snf1)-related protein kinases have evolved. While the Snf1-related protein kinase 1 (SnRK1) subfamily has been shown to share pivotal roles with the orthologous yeast Snf1 and mammalian AMP-activated protein kinase in modulating energy and metabolic homeostasis, the functional significance of the two plant-specific subfamilies SnRK2 and SnRK3 in these critical processes is poorly understood. We show here that SnRK2.6, previously identified as crucial in the control of stomatal aperture by abscisic acid (ABA), has a broad expression pattern and participates in the regulation of plant primary metabolism. Inactivation of this gene reduced oil synthesis in Arabidopsis (Arabidopsis thaliana) seeds, whereas its overexpression increased Suc synthesis and fatty acid desaturation in the leaves. Notably, the metabolic alterations in the SnRK2.6 overexpressors were accompanied by amelioration of those physiological processes that require high levels of carbon and energy input, such as plant growth and seed production. However, the mechanisms underlying these functionalities could not be solely attributed to the role of SnRK2.6 as a positive regulator of ABA signaling, although we demonstrate that this kinase confers ABA hypersensitivity during seedling growth. Collectively, our results suggest that SnRK2.6 mediates hormonal and metabolic regulation of plant growth and development and that, besides the SnRK1 kinases, SnRK2.6 is also implicated in the regulation of metabolic homeostasis in plants.Plants are constantly confronted by biotic and abiotic stresses and nutrient deprivation that disrupt metabolic and energy homeostasis or diminish carbon and energy availability for maintaining cell vitality, growth, and proliferation. It is believed that maintaining energy balance and availability at the cellular and organism levels is critical for optimizing plant growth and development. This underscores the cellular and physiological importance of energy sensors that control energy balance through regulating fundamental metabolic pathways in response to nutritional and environmental stresses.At present, a prevailing view is that energy sensors are evolutionarily conserved in eukaryotes, which are represented by Snf1 (for sucrose nonfermenting-1) in yeast, AMPK (for AMP-activated protein kinase) in

Alginate oligosaccharides enhanced Triticum aestivum L. tolerance to drought stress

“…Increasing evidences show that SnRK2 participates in complicated network to respond to hyperosmotic stress and ABA signaling pathway [31,32]. Gene product of SnRK2 can phosphorylate AREB polypeptides in vitro [33].…”

PYR/RCAR Receptors Contribute to Ozone-, Reduced Air Humidity-, Darkness-, and CO2-Induced Stomatal Regulation

“…In addition to ABAdependent activation, ABA-independent activation of OST1 might be induced by osmotic and lowhumidity stress (Xie et al, 2006;Yoshida et al, 2006;Boudsocq et al, 2007). Furthermore, many OST1-inducible genes are not responsive to ABA (Zheng et al, 2010). Figure 3, A to C. Significant differences (P , 0.05; n = 5-50) are denoted with different lowercase letters.…”

The PP6 Phosphatase Regulates ABI5 Phosphorylation and Abscisic Acid Signaling inArabidopsis

“…] OST1 (SnRK2.6) plays a critical role in mediating various ABA responses, and its loss-of-function mutant (ost1 or snrk2.6) displays a hypersensitive phenotype in response to drought stress and resistance to ABA during seed germination (Li et al, 2000;Mustilli et al, 2002;Yoshida et al, 2006;Zheng et al, 2010). Additionally, the single mutants of snrk2.2 and snrk2.3 do not display obvious ABA-related phenotypes, whereas ost1 is more resistant to ABA during seed germination than the wild type (Fujii et al, 2007;Zheng et al, 2010). We therefore introduced the ost1 mutation into f1 2/+ f3 and F3DN mutant backgrounds.…”