The vacuolar proton pyrophosphatase gene (SbVPPase) from the Sorghum bicolor confers salt tolerance in transgenic Brahmi [Bacopa monnieri (L.) Pennell]

Abstract

Plants overcome the effect of Na toxicity either by excluding Na at the plasma membrane or by sequestering them into the vacuoles. Influx of Na ions into the plant vacuoles is usually driven by H generated by vacuolar-type H-ATPase as well as vacuolar proton pyrophosphatse (VPPase). In the present study, we have developed transgenics via containing the recombinant vector pCAMBIA2300- gene. Transformants were produced using nodal explants. Transformants were confirmed by PCR and DNA blot analysis. qPCR analysis showed higher transcript levels of compared to untransformed control (UC). Higher VPPase activity was recorded in transgenics compared to UC. Under 150 mM salt stress, transgenic shoots showed enhanced Na accumulation with better biomass production, increased glycine betaine content, and total soluble sugar levels than UC. Transgenic shoots showed 2.9-3.8-folds lower levels of malondialdehyde content indicating lesser membrane damage. Increase in antioxidant enzyme activities (1.4-3.2-folds) was observed in transgenics compared to UC. Transgenics also displayed 7.3-9.0-folds enhanced accumulation of the medicinally important compound bacoside A. Increased biomass production, accumulation of Na, osmolytes (glycine betaine, sugars etc.), and elevated antioxidant enzyme activities indicate better osmotic adjustment in transgenics by compartmentalization of Na into the vacuoles under salt stress conditions. Thus, overexpression of in alleviated salt stress by sequestering Na.

Targeting Glycinebetaine for Abiotic Stress Tolerance in Crop Plants: Physiological Mechanism, Molecular Interaction and Signaling

“…The transgenic plants also exhibited better regulation of the ion channels like K + transporter, Na + /H + antiporter and H + -ATPase under stress, which led to a higher K + /Na + ratio compared to the stressed seedlings [42]. The relation between ion channel regulation and GB accumulation has also been observed by Ahire et al [191] where overexpression of vacuolar proton pyrophosphatase (VPPase) from Sorghum bicolor in Bacopa monnieri conferred salt tolerance via enhanced production of GB. The shoots of the transgenic plants also accumulated low MDA and exhibited lesser membrane damage due to GB-mediated recharging of the antioxidant machinery and effective scavenging of toxic ROS [191].…”

“…The relation between ion channel regulation and GB accumulation has also been observed by Ahire et al [191] where overexpression of vacuolar proton pyrophosphatase (VPPase) from Sorghum bicolor in Bacopa monnieri conferred salt tolerance via enhanced production of GB. The shoots of the transgenic plants also accumulated low MDA and exhibited lesser membrane damage due to GB-mediated recharging of the antioxidant machinery and effective scavenging of toxic ROS [191]. Overexpression of the S. oleracea chloroplastidic BADH in sweet potato cv.…”

The H+-Translocating Inorganic Pyrophosphatase From Arabidopsis thaliana Is More Sensitive to Sodium Than Its Na+-Translocating Counterpart From Methanosarcina mazei

“…Several groups have reported that stable overexpression of H + -PPases stimulates growth and increases tolerance to biotic and abiotic stresses of A. thaliana and many other plants, however, in these reports plants overexpressing other types of PPases were never used as controls ( Gaxiola et al., 2001 ; Park et al., 2005 ; Gao et al., 2006 ; Li et al., 2008 ; Lv et al., 2008 ; Pasapula et al., 2011 ; Schilling et al., 2014 ; Yang et al., 2015 ; Lv et al., 2016 ; Ahire et al., 2018 ). This makes difficult to ascertain the degree of involvement of the two activities exhibited by H + -PPases (PPi hydrolysis and H + -pumping) in stress tolerance.…”

“…In a seminal paper published in 2001, Gaxiola and co-workers reported that overexpression of AVP1 alleviated the sensitivity of A. thaliana to NaCl ( Gaxiola et al., 2001 ). Thereafter, several groups obtained other plants with higher tolerance to salinity and other stresses based on this approach ( Park et al., 2005 ; Gao et al., 2006 ; Li et al., 2008 ; Lv et al., 2008 ; Pasapula et al., 2011 ; Gaxiola et al., 2012 ; Schilling et al., 2014 ; Yang et al., 2015 ; Lv et al., 2016 ; Ahire et al., 2018 ). This strategy had been originally tested in S. cerevisiae ( Gaxiola et al., 1999 ), thus demonstrating the suitability of this yeast to study and test solutions to salt stress in plants.…”

Mutagenesis Reveals That the OsPPa6 Gene Is Required for Enhancing the Alkaline Tolerance in Rice

“…Our data also demonstrate a closely association between the OsGS2 activity and proline accumulation in rice in response to AS, and both soluble sugar and MDA exhibit the differentially accumulated responses to the abiotic stresses, and leading to the changes of osmotic potentials in plant cells (Mittler, 2002; Lv et al, 2013). Both the transgenic Eleusine coracana and Brahmi overexpressing a SbVPPase gene, encodes a vacuolar proton pyrophosphatase in Sorghum bicolor , increases the accumulation of proline and soluble sugar, but reduces the MDA contents under salt stress (Anjaneyulu et al, 2014; Ahire et al, 2018). In our study, the mutagenesis of the OsPPa6 gene might be an important modulator lowering the contents of soluble sugar and proline, and increasing osmotic potentials and MDA accumulation in the mutants because of the activity changes of the sPPase under AS, indicating that the loss of function of the OsPPa6 gene affected the accumulation of compatible solutes in rice and exerted negative effects on the maintenance of the osmotic equilibrium in plant cells, and aggravated the alkali damage to the plant cell membranes.…”