Genetic Manipulation of a “Vacuolar” H+-PPase: From Salt Tolerance to Yield Enhancement under Phosphorus-Deficient Soils

H+‐pyrophosphatase IbVP1 promotes efficient iron use in sweet potato [Ipomoea batatas(L.) Lam.]

“…Pyrophosphatases generate energy and release free Pi, which affects plant carbon metabolism (Gaxiola et al ., 2012; Geigenberger et al ., 1998). The altered partitioning of photoassimilate in tobacco and potato expressing an Escherichia coli cytosolic inorganic pyrophosphatase gene (Sonnewald, 1992) and the suppression of sucrose synthesis in the cotyledons of avp Arabidopsis mutant (Ferjani et al ., 2011) support the significant role of PPases in sucrose metabolism.…”

“…Further, the high expression of IbVP1 in young storage root indicates an important function related to storage root development (Figure 2). These results further confirmed that up‐regulation of H + ‐PPase promoted translocation of photosynthates from leaf to root, as hypothesized previously (Gaxiola et al ., 2012; Hermans et al ., 2006; Khadilkar et al ., 2016; Paez‐Valencia et al ., 2011). A recent study also demonstrated that increased sucrose accumulation was required for the regulation of auxin‐mediated Fe deficiency in plants (Lin et al ., 2016).…”

“…Up‐regulated H + ‐PPases induce plant tolerance to various stresses, such as drought, high salinity, and N and Pi deprivation (Arif et al ., 2013; Paez‐Valencia et al ., 2013; Yang et al ., 2007). It also affects auxin and sugar transport and accumulation during root and shoot growth (Gaxiola et al ., 2012; Khadilkar et al ., 2016; Li et al ., 2005; Pasapula et al ., 2011; Pizzio et al ., 2015). …”

Structural basis for the reversibility of proton pyrophosphatase

“…8,[11][12][13] Thermodynamic, 14 genetic, immunohistochemical, and physiological evidence 8,15,16 is consistent with a reverse PPi synthase activity of H C -PPase at the PM in the phloem, where it plays an important role in PPi homeostasis and photosynthate partitioning. 10,[15][16][17] We contend that the magnitude of proton gradients associated with the tonoplast or PM location of this enzyme drives the protein's structurally congruent potential to work in a reversible manner -either in the synthesis or hydrolysis of its substrate, PPi. 10,17 That the proton gradient drives the hydrolytic or synthetic activity of H C -PPase is corroborated by experimental evidence in maize coleoptiles and oranges.…”

“…10,[15][16][17] We contend that the magnitude of proton gradients associated with the tonoplast or PM location of this enzyme drives the protein's structurally congruent potential to work in a reversible manner -either in the synthesis or hydrolysis of its substrate, PPi. 10,17 That the proton gradient drives the hydrolytic or synthetic activity of H C -PPase is corroborated by experimental evidence in maize coleoptiles and oranges. 18,19 The dual membrane-specificity and the concomitant reversibility is in fact not a novel plant-specific attribute of this elegant pump.…”