Effect of NaCl on leaf H+-ATPase and the relevance to salt tolerance in two contrasting poplar species

Abstract

During a 30-day period of increasing salinity, we examined the effects of NaCl on leaf H? -ATPase and salinity tolerance in 1-year-old plants of Populus euphratica Oliv. (salt resistant) and P. popularis 35-44 (P. popularis) (salt sensitive). Electron probe X-ray microanalysis of leaf mesophyll revealed that P. euphratica had a higher ability to retain lower NaCl concentrations in the cytoplasm, as compared to P. popularis. The sustained activity of H ? pumps (by cytochemical staining) in salinised P. euphratica suggests a role in energising salt transport through the plasma membrane (PM) and tonoplast. Saltinduced alterations of leaf respiration, ATP content and expression of PM H ? -ATPase were compared between the two species. Results show that P. euphratica retained a constant respiratory rate, ATP production and protein abundance of PM H ? -ATPase (by Western blotting) in salt-stressed plants. P. euphratica was able to maintain a comparatively high capacity of ATP hydrolysis and H ? pumping during prolonged salt exposure. By contrast, the activity and expression of PM H ? -ATPase were markedly decreased in P. popularis leaves in response to salt stress. Furthermore, NaCl-stressed P. popularis plants showed a marked decline of respiration (70%) and ATP production (66%) on day 30. We conclude that the inability of P. popularis to transport salt to the apoplast and vacuole was partly due to the decreased activity of H ? pumps. As a consequence, cytosolic ion concentrations were observed to be comparatively high for an extended period of time, so that cell metabolism, in particular respiration, was disrupted in P. popularis leaves.

Ectomycorrhizas with Paxillus involutus enhance cadmium uptake and tolerance in Populus × canescens

“…; Ma et al . ) and mediating seasonal signals in cambial cells of poplars (Arend et al . ), scarce information is available on transcriptional regulation of genes encoding PM H + ‐ATPases.…”

“…× canescens may lead to higher activities of PM H + -ATPases and thus, higher H + release, driving higher Cd 2+ absorption rates in EMs. Although the roles of PM H + -ATPases have been documented in uptake of NH4 + and NO3 − , cellular Na + extrusion (Beritognolo et al 2007;Ma et al 2010) and mediating seasonal signals in cambial cells of poplars (Arend et al 2002), scarce information is available on transcriptional regulation of genes encoding PM H + -ATPases. Down-regulated transcripts of genes coding PM H + -ATPases have been reported for leaves of Po.…”

Salt Compartmentation and Antioxidant Defense in Roots and Leaves of Two Non-Salt Secretor Mangroves under Salt Stress

“…Salt induced an oxidative stress in chloroplast and mitochondria of pea leaves [28][29][30]34]. In poplars, great buildup of Na + and Cl À in chloroplasts may directly cause ion toxicity and induce the subsequent oxidative stress [26,38]. X-ray microanalysis results showed that the inability for the restriction of Na + entry into the chloroplasts leads to an uncontrolled oxidation in Populus popularis [26,38].…”

“…In poplars, great buildup of Na + and Cl À in chloroplasts may directly cause ion toxicity and induce the subsequent oxidative stress [26,38]. X-ray microanalysis results showed that the inability for the restriction of Na + entry into the chloroplasts leads to an uncontrolled oxidation in Populus popularis [26,38]. Salt-resistant plants may maintain ROS homeostasis through limiting ROS production by a protective salt partitioning.…”

Paxillus involutus-Facilitated Cd2+ Influx through Plasma Membrane Ca2+-Permeable Channels Is Stimulated by H2O2 and H+-ATPase in Ectomycorrhizal Populus × canescens under Cadmium Stress

“…In agreement with this suggestion transgenic poplars that were more Cd 2+ tolerant by overexpression of γ-glutamylcysteine synthetase, showed upregulated transcript levels of VHA1.1 , HA2.1 and AHA10.1 and a high Cd 2+ uptake rate (He et al, 2015). The PM H + -ATPases maintain a H + gradient across the membrane to promote active transport of essential elements across the PM (Beritognolo et al, 2007; Ma et al, 2010; Sun et al, 2010; Luo et al, 2013). Increased H + -pumping activities have been well characterized in arbuscular mycorrhizal associations (Ramos et al, 2005; Rosewarne et al, 2007) and in ectomycorrhizal associations formed by Paxillus involutus (strains MAJ and NAU) with Populus × canescens (Li J. et al, 2012).…”