Abstract
This mini-review briefly presents the main types of plant aquaporins, highlighting their importance for different plant species and for plant cellular functions. Aquaporins (AQPs), families of water channel proteins (WCPs) are transmembrane proteins that are present in prokaryotes, animals, plants, and humans. The plant aquaporins are part of the Major Intrinsic Proteins (MIPs) family which resides in the following plant organs: roots, stems, leaves, flowers, fruits, and seeds. According to the sub-cellular localization, to their sequence homologies and to their phylogenetic distribution, plant aquaporins have been divided in five subgroups: (a) plasma membrane intrinsic proteins (PIPs); (b) tonoplast intrinsic proteins (TIPs); (c) Nodulin26-like intrinsic membrane proteins (NIPs); (d) small basic intrinsic proteins (SIPs) and (e) uncharacterized intrinsic proteins (XIPs). Different subclasses of the plant aquaporins allow several types of transport using: water, glycerol, urea, hydrogen peroxide, organic acids, ethanol, methanol, arsenite, lactic acid, and gaseous compounds. Plant aquaporins have a significant role in cell response to cold stress, photosynthesis, plant growth, cell elongation, reproduction, and seed germination.