Transcriptional regulation of the V‐ATPase subunit c and V‐PPase isoforms in Cucumis sativus under heavy metal stress

Abstract

Two electrogenic proton pumps, vacuolar H(+) transporting ATPase (V-ATPase, EC 3.6.3.14) and vacuolar H(+) transporting inorganic pyrophosphatase (V-PPase, EC 3.6.1.1), co-exist in the vacuolar membrane of plant cells. In this work, all CsVHA and CsVHP genes encoding V-ATPase and V-PPase, respectively, were identified in the cucumber genome. Among them, three CsVHA-c genes for V-ATPase subunit c and two CsVHP1 genes for type I V-PPase were analyzed in detail. Individual isogenes were differentially regulated in plant tissues and during plant development as well as under changing environmental conditions. CsVHA-c1 and CsVHA-c2 showed similar tissue-specific expression patterns with the highest levels in stamens and old leaves. CsVHP1;1 was predominantly expressed in roots and female flowers. In contrast, both CsVHA-c3 and CsVHP1;2 remained in a rather constant ratio in all examined cucumber organs. Under heavy metal stress, the transcript amount of CsVHA-c1 and CsVHP1;1 showed a pronounced stress-dependent increase after copper and nickel treatment. CsVHA-c3 was upregulated by nickel only whereas CsVHA-c2 was induced by all metals with the most visible effect of copper. Additionally, CsVHP1;2 showed a tendency to be upregulated by copper and zinc. We propose that CsVHA-c1, CsVHA-c2 and CsVHP1;1 are essential elements of mechanisms involved in adaptation of cucumber plants to copper toxicity.

Vacuolar compartmentalization as indispensable component of heavy metal detoxification in plants

“…Recently, Kabala et al . () demonstrated differential transcriptional responses of three isoforms (CsVHA‐c1, CsVHA‐c2 and CsVHA‐c3) of the subunit c of V‐ATPase in Cucumis sativus under HM stress. Thus, the transcript amounts of CsVHA‐c1 increased due to a 24 h Cu and Ni treatment and those of CsVHA‐c3 due to Ni only.…”

“…sativus roots points to a role of CsVHP1 ; 1 under Cu stress (Kabala et al . ). As in the case of VHA‐a, the V‐PPase mRNA levels were increased in shoots of A .…”

“…In a subsequent detailed sequence analysis, the assayed VHA‐c corresponded to the CsVHA‐c3 isogene that was not, while other two isogenes were, influenced by Cu (Kabala et al . ). Furthermore, a pre‐incubation of control tonoplast vesicles with Cu (1–1000 μ m ), but not Cd, led to stimulated V‐ATPase activity, suggesting a direct activation at least by Cu ions (Kabala et al .…”

Drought-Responsive Mechanisms in Plant Leaves Revealed by Proteomics

“…V-ATPase and V-PPase are two tonoplast proton pumps for translocating H + into the vacuoles to generate a gradient of H + , which provide a driving force for the accumulation of ions and other solutes in the vacuole. Their functions in plant abiotic stress tolerance have been widely discussed [187,188]. For example, an M .…”

Chinese wheat mosaic virus‐derived vsiRNA‐20 can regulate virus infection in wheat through inhibition of vacuolar‐ (H+)‐PPase induced cell death

“…In plant, there are three distinct membrane H + -pumps that can generate pH gradients: the P-type (H + )-ATPase in plasma membrane to export H + from cells (Serrano, 1993); the vacuolar (H + )-ATPase (V-ATPase) complexes that are encoded by ≥ 26 genes and can acidify vacuoles and other intracellular trafficking compartments (Strompen et al, 2005); and the vacuolar (H + )-PPases (VPs) that are single subunit proteins and can generate H + gradients in endomembrane compartments using PPi (Zhen et al, 1997). Expression of the VP gene can be upregulated by various abiotic stresses, including low nutrient, drought, cold, heat, heavy metal and salinity stresses (Gaxiola et al, 2001;Han et al, 2005;Queiros et al, 2009;Kabala et al, 2014;Wehner et al, 2015;Graus et al, 2018). Previous studies have shown that overexpression of VP genes can enhance drought and/or salinity stress tolerance in plants, including Arabidopsis thaliana, Suaeda salsa, wheat (Triticum aestivum) and Nicotiana benthamiana (Gaxiola et al, 2001;Gao et al, 2006;Guo et al, 2006;Brini et al, 2007;Graus et al, 2018).…”