Plant Growth In Arabidopsis Research Articles

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

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.

Overexpression of the Na+/H+ antiporter gene from Suaeda salsa confers cold and salt tolerance to transgenic Arabidopsis thaliana

Na+/H+ exchanger catalyzes the countertransport of Na+ and H+ across membranes. By using reverse transcription PCR (RT-PCR) technique and Rapid Amplification of cDNA Ends (RACE), a Suaeda salsa cDNA clone was isolated and the sequence contains 2133 bp with an open reading frame of 1674 bp. The deduced amino acid sequence is similar to that of AtNHX1 and NHE isoforms in mammals, and shares high similarity with the sequences within predicted transmembrane segments and an amiloride-binding domain. In an attempt to improve salt tolerance of Arabidopsis plants, an expression vector containing SsNHX1 cDNA driven by a cauliflower mosaic virus 35S promoter was transferred into Arabidopsis plants. Transgenic plants could normally grow and complete life cycle under treatment with 200 mM NaCl but the wild-type Arabidopsis plant growth were severely retarded. Transgenic seedlings could resume and keep normal growth after treatment at −7°C for 5 h but wt plants became hoariness and then all died.