Abscisic acid-regulated water channels and their role in plant acclimation and tolerance to water stress

The yield of worldwide crop production has already been negatively affected by high salinity and water deficiency prevailing in many of the cultivated lands (Yan et al., 2013Serraj et al., 2011Golldack et al., 2011). Consequently, reduced crop production is a major problem in terms of food sustainability world-wide (Spiertz, 2013). Plants as sessile organisms have to dynamically and constantly cope with various types of stress in their environment. Although stress perception by plants remains elusive (Gan et al., 2010Shachar-Hill et al., 2013Wu et al., 2012), the stress-responsive mechanisms that follow are starting to be better understood (Wasilewska et al., 2008Kohli et al., 2013Osakabe et al., 2013). Abscisic acid (ABA) is a central plant hormone produced in response to abiotic stress and has been shown to play important roles in plant acclimation and tolerance towards stress (Nakashima and Yamaguchi-Shinozaki, 2013Osakabe et al., 2014). ABA accumulation triggers the expression of a plethora of genes within the plant cell (Liu et al., 2013). The ABA-regulated genes are various in nature, including enzymes involved in osmolyte and cell wall biosynthesis, detoxifying enzymes, enzymes for fatty acid metabolism, proteinase inhibitors, macromolecule protective proteins, lipid transfer proteins, ion transporters and water channels, transcription factors (TFs), protein kinases, protein phosphatases and proteinases (Roychoudhury et al., 2013Rock, 2000). In this literature review the role of water channel-encoding genes, namely aquaporins (AQPs), in plant water stress will be discussed. The aim of this study is to understand how ABA-regulated AQPs are able to contribute to the plant’s tolerance and acclimation during water stress. The knowledge gained from this study is important for the engineering of salt and drought resistant crops within the modern agricultural context, thus contributing to world’s crop sustainable production (Jacobs et al., 2011Park et al., 2005Kujur et al., 2013)