Multifaceted roles of aquaporins as molecular conduits in plant responses to abiotic stresses

Abstract

Abiotic stress has become a challenge to food security due to occurrences of climate change and environmental degradation. Plants initiate molecular, cellular and physiological changes to respond and adapt to various types of abiotic stress. Understanding of plant response mechanisms will aid in strategies aimed at improving stress tolerance in crop plants. One of the most common and early symptoms associated with these stresses is the disturbance in plant-water homeostasis, which is regulated by a group of proteins called "aquaporins". Aquaporins constitute a small family of proteins which are classified further on the basis of their localization, such as plasma membrane intrinsic proteins, tonoplast intrinsic proteins, nodulin26-like intrinsic proteins (initially identified in symbiosomes of legumes but also found in the plasma membrane and endoplasmic reticulum), small basic intrinsic proteins localized in ER (endoplasmic reticulum) and X intrinsic proteins present in plasma membrane. Apart from water, aquaporins are also known to transport CO2, H2O2, urea, ammonia, silicic acid, arsenite and wide range of small uncharged solutes. Besides, aquaporins also function to modulate abiotic stress-induced signaling. Such kind of versatile functions has made aquaporins a suitable candidate for development of transgenic plants with increased tolerance toward different abiotic stress. Toward this endeavor, the present review describes the versatile functions of aquaporins in water uptake, nutrient balancing, long-distance signal transfer, nutrient/heavy metal acquisition and seed development. Various functional genomic studies showing the potential of specific aquaporin isoforms for enhancing plant abiotic stress tolerance are summarized and future research directions are given to design stress-tolerant crops.

Regulation of gene expression by NFAT transcription factors in hibernating ground squirrels is dependent on the cellular environment

“…Therefore, it would not be able to translocate passively into the nucleus without the aid of channel proteins or transporters. Aquaporin proteins are a family of water-channel proteins that are known to transport urea, and they have been shown to reside partially on the nuclear membrane (Srivastava et al 2014;Sato et al 2011). Therefore, it is possible for urea to accumulate inside the nucleus, but as we have shown, the amount of nuclear urea is insufficient to significantly affect NFAT binding to DNA.…”

Heterologous Expression of Panax ginseng PgTIP1 Confers Enhanced Salt Tolerance of Soybean Cotyledon Hairy Roots, Composite, and Whole Plants

“…They locate in the plasma and intracellular membranes of plant cells, where they facilitate the transport of water and/or a wide range of small neutral or uncharged solutes (glycerol, urea, boric acid, silicic acid, arsenite, ammonia, CO 2 , and H 2 O 2 , etc.) (Katsuhara et al, 2008; Maurel et al, 2008; Chaumont and Tyerman, 2014; Srivastava et al, 2014; Tian et al, 2016; Wang et al, 2016). Based on sequence homology or similarity, subcellular localization, and expression patterns, plant AQPs can generally be classified into five subfamilies: plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), nodulin26-like intrinsic proteins (NIPs), small and basic intrinsic proteins (SIPs), and uncategorized X intrinsic proteins (XIPs) (Kaldenhoff and Fischer, 2006; Danielson and Johanson, 2008).…”

Plant Aquaporins: Genome-Wide Identification, Transcriptomics, Proteomics, and Advanced Analytical Tools

“…Subsequently, Peter Agre's team proved through cRNA expression studies that those proteins, named aquaporin-1, were specific water channels (Preston et al, 1992), and Agre was awarded the Nobel Prize in chemistry in 2003 for his discovery (Agre, 2004). These findings have sparked a veritable explosion of work that has enhanced our understanding of the importance of AQPs in animals as well as in plants (Papadopoulos and Verkman, 2013; Deshmukh et al, 2015; Kitchen et al, 2015; Maurel et al, 2015; Kirscht et al, 2016; Srivastava et al, 2016). …”