Plant Aquaporins and Abiotic Stress

Abstract

Festuca arundinacea and F. pratensis are the models in forage grasses to recognize the molecular basis of drought, salt and frost tolerance, respectively. Transcription profiles of plasma membrane intrinsic proteins (PIPs) and to-noplast intrinsic proteins (TIPs) aquaporin genes were obtained for leaves of Festuca species treated with different abiotic stimuli. F. arundinacea plants were exposed to drought and salt stress, whereas F. pratensis plants were cold-hardened. Changes in genes expression measured with use of real time qRT-PCR method were compared between two genotypes characterized with a significantly different level of each stress tolerance. Under drought the transcript level of PIP1;2 and TIP1;1 aquaporin decreased in both analyzed F. arundinacea genotypes, whereas for PIP2;1 only in a high drought tolerant plant. A salt treatment caused a reduction of PIP1;2 transcript level in a high salt tolerant genotype and an increase of TIP1;1 transcript abundance in both F. arundinacea genotypes, but it did not influence the expression of PIP2;1 aquaporin. During cold-hardening a decrease of PIP1;2, PIP2;1, and TIP1;1 aquaporin transcripts was observed, both in high and low frost tolerant genotypes. The obtained results revealed that the selected genotypes responded in a different way to abiotic stresses application. A reduced level of PIP1;2 transcript in F. arundinacea low drought tolerant genotype corresponded with a faster water loss and a lowering of photosynthesis efficiency and gas exchange during drought conditions. In F. pratensis, cold acclimation was associated with a lower level of aquaporin transcripts in both high and low frost tolerant genotypes. This is the first report on aquaporin transcrip-tional profiling under abiotic stress condition in forage grasses.

Aquaporin mediating stomatal closure is associated with water conservation under mild water deficit

“…In severe soil water deficit conditions (Ψ soil ≈ −0.30∼−0.50 MPa), the PIP2;5 OE maize lines may maintain root water uptake ability and leaf hydraulic conductance (Ding et al , 2020), resulting in similar or even higher plant transpiration and growth as in WT plants. Altogether, these data indicate that the beneficial effect of PIP2;5 overexpression is really dependent on water stress conditions and that, in mild water deficit, PIP2;5 OE lines perform better than control plants by faster stomatal closing and/or increased root water uptake ability, as previously observed for plants overexpressing other PIP aquaporins (Groszmann et al , 2017; Sade & Moshelion, 2017),…”

Mesophyll Abscisic Acid Restrains Early Growth and Flowering But Does Not Directly Suppress Photosynthesis

“…ABA has been reported to affect the transcription of thousands of genes (Nemhauser et al, 2006) and is reported to have significant redundancy in its signal transduction pathway (Umezawa et al, 2010). Moreover, the ABA response varies in different tissues and under different environmental conditions (Saab et al, 1990;Sade and Moshelion, 2017). This complexity makes it hard to isolate the role of ABA in specific processes.…”

Is Nitrogen a Key Determinant of Water Transport and Photosynthesis in Higher Plants Upon Drought Stress?

“…In soil-plant-atmosphere continuum system, water travels from soil to the atmosphere. Two water flow pathways are included in this process: axial movement (water flow from root xylem to leaf vessels) and radial movement (water flow from soil to root xylem and from leaf xylem vessels to mesophyll cells) ( Sade and Moshelion, 2017 ). The whole plant hydraulic conductance is determined by radial conductance, that is, root hydraulic conductivity (Lpr) and leaf hydraulic conductance (K leaf ), since water must pass through apoplastic barriers, which resist the water flow ( Steudle and Peterson, 1998 ; Sack and Holbrook, 2006 ).…”

“…The whole plant hydraulic conductance is determined by radial conductance, that is, root hydraulic conductivity (Lpr) and leaf hydraulic conductance (K leaf ), since water must pass through apoplastic barriers, which resist the water flow ( Steudle and Peterson, 1998 ; Sack and Holbrook, 2006 ). During drought stress, both Lpr and K leaf are affected in higher plants ( Aroca and Ruiz-Lozano, 2012 ; Sade and Moshelion, 2017 ).…”