Genome-Wide Identification and Transcriptional Regulation of Aquaporin Genes in Bread Wheat (Triticum aestivum L.) under Water Stress

Abstract

Aquaporins (AQPs) are transmembrane proteins essential for controlling the flow of water and other molecules required for development and stress tolerance in plants, including important crop species such as wheat (Triticum aestivum). In this study, we utilized a genomic approach for analyzing the information about AQPs available in public databases to characterize their structure and function. Furthermore, we validated the expression of a suite of AQP genes, at the transcriptional level, including accessions with contrasting responses to drought, different organs and water stress levels. We found 65 new AQP genes, from which 60% are copies expanded by polyploidization. Sequence analysis of the AQP genes showed that the purifying selection pressure acted on duplicate genes, which was related to a high conservation of the functions. This situation contrasted with the expression patterns observed for different organs, developmental stages or genotypes under water deficit conditions, which indicated functional divergence at transcription. Expression analyses on contrasting genotypes showed high gene transcription from Tonoplast Intrinsic Protein 1 (TIP1) and 2 (TIP2), and Plasma Membrane Intrinsic Protein 1 (PIP1) and 2 (PIP2) subfamilies in roots and from TIP1 and PIP1 subfamilies in leaves. Interestingly, during severe drought stress, 4 TIP genes analyzed in leaves of the tolerant accession reached up to 15-fold the level observed at the susceptible genotype, suggesting a positive relationship with drought tolerance. The obtained results extend our understanding of the structure and function of AQPs, particularly under water stress conditions.

The Tonoplast Intrinsic Protein Gene KvTIP3 is Responsive to Different Abiotic Stresses in Kosteletzkya virginica

“…KvTIP3 was upregulated by low temperature and ABA but downregulated by high temperature and osmotic stress (Figures 4(a)-4(d)). is is consistent with previous studies that the responses of AQPs under adverse environment were diverse [49]. e responses of KvTIP3 under high temperature and osmotic stress were not obvious (Figures 4(c) and 4(d)).…”

Genome-wide identification of candidate aquaporins involved in water accumulation of pomegranate outer seed coat

“…Motifs 1, 2, 3, 6, 8, and 10 were common for TIP and NIP subfamily members, except for PgrNIP7.1. Interestingly, motifs 4 and 5 were only identified in the PIP subfamily and similar motifs were found in bread wheat, indicating the PIP subfamily may have unique functions (Madrid-Espinoza et al, 2018).…”

Aquaporins in Cereals—Important Players in Maintaining Cell Homeostasis under Abiotic Stress

“…The main function of aquaporins under drought stress is to precisely regulate the movement of water among cells and tissues [ 86 ]. An analysis of the AQP gene expression in the leaf and/or root tissues in barley ( Hordeum vulgare L.), foxtail millet ( Setaria italica L.), rice ( Oryza sativa L.) and wheat ( Triticul aestivum L.) revealed significant changes in their response to drought or dehydration stress, which had been induced by the application of polyethylene glycol-6000 (PEG) ( Table 2 ) [ 61 , 66 , 75 , 80 , 81 ]. Applying 20% PEG is equivalent to osmotic potential levels of −1.09 MPa [ 87 ].…”

“…In the case of the TIP family, TaTIP2-4 , TaTIP3-4 and TaTIP4-1 also increased their expression levels during severe stress. On the other hand, in the roots, the tolerant genotype had a lower level of expression compared to the susceptible ones for the TaPIP1-1 , TaPIP1-5 , TaAQP7 , TaPIP2-1C1 , TaTIP1-2 , TaTIP3-4 and TaTIP4-1 genes under moderate stress [ 61 ].…”