Effect of Anoxia on ATP Levels and Ion Transport Rates in Red Beet

Abstract

in closed 25-ml flasks containing 5-7 ml experimental solution at 30 C. Peristaltic pumps were used to empty and refill the flasks at intervals without exposure to air. N2 treatments were applied by passing 02-free N2 gas into the flasks and at the same time replacing the solutions with solutions equilibrated with N2. For measurements of ATP content under N2, liquid N2 was poured into the flasks to freeze the tissue before exposing it to air. The frozen tissue was then extracted as described previously (2). RESULTS AND DISCUSSIONIn the preceding paper (2), we have presented evidence that the plasmalemma influxes of K+ and Cl-in storage tissue of red beet are both closely dependent on the ATP level in the tissue. This conclusion is contrary to that of Polya and Atkinson (3). Among the lines of evidence adduced by the latter investigators in favor of another energy source is that a N2 atmosphere did not appear to alter ATP levels, although it strongly inhibited ion fluxes. Here, we repeat the measurements ofATP content under N2 atmosphere, with opposite results to those of Polya and Atkinson (3). We also show that plasmalemma fluxes are inhibited within 1 min or less following removal of 02. This response is too rapid to be attributable to ATP-dependent changes in tonoplast transport, and thus indicates a more direct dependence of plasmalemma influxes on ATP.

Partial characterization of a phosphorylated intermediate associated with the plasma membrane ATPase of corn roots

“…Cellular ATP levels have been correlated with the rates of ion uptake (28), and recent studies with isolated membrane vesicles have demonstrated ATP-dependent, electrogenic proton transport (2,19). Similarities between the kinetics of K+ stimulation of ATPase and K+ uptake 6926 Botany: Briskin and Leonard into roots (18) and an analysis of K+ uptake data with respect to membrane potential (29) are consistent with a direct role for this enzyme in driving K+ transport.…”

Voltage-Dependent Anion-Selective Channels and Other Mitochondrial Membrane Proteins Form Diverse Complexes in Beetroots Subjected to Flood-Induced Programmed Cell Death

“…Beetroot cells are sensitive to anoxia and dependent on mitochondrial respiration for their energy needs ( Petraglia and Poole, 1980 ). The anoxia caused by flooding inhibits growth and produces PCD ( Chen et al, 2014 ; Kamal and Komatsu, 2015 ; Qi et al, 2018 ).…”

“…Since Beta vulgaris roots are reported to be sensitive to hypoxia ( Petraglia and Poole, 1980 ), it is conceivable that flooding could be an easy and adequate method to induce PCD in bulky roots similar to them. Then, after observing changes in the cell and nuclear morphology associated with cell death and the leakage of cyt c from mitochondria in flood-treated beetroots, it was concluded that flood stress could cause PCD in them.…”