K. Benabdellah et al., Plasma membrane ATPase and H+ transport activities in microsomal membranesfrom mycorrhizal tomato roots, J EXP BOT, 50(337), 1999, pp. 1343-1349
ATPase activity, ATP-dependent H+ transport and the amount of antigenic tom
ato plasma membrane H+-ATPase have been analysed in membrane vesicles isola
ted from Glomus mosseae- or Glomus intraradices-colonized roots and from no
n-mycorrhizal tomato roots. Microsomal protein content was higher in mycorr
hizal than in control roots. The specific activity of the plasma membrane H
+-ATPase was not affected by mycorrhizal colonization, although this activi
ty increased in membranes isolated from mycorrhizal roots when expressed on
a fresh weight basis. Western blot analysis of microsomal proteins using a
ntibodies raised against the Arabidopsis thaliana plasma membrane H+-ATPase
showed that mycorrhizal colonization did not change the relative amount of
tomato plasma membrane ATPase in the microsomes. However, on a fresh weigh
t basis, there was a greater amount of this protein in roots of mycorrhizal
plants. In addition, mycorrhizal membranes showed a higher specific activi
ty of the vanadate-sensitive ATP-dependent H+ transport than membranes isol
ated from control roots. These results suggest that mycorrhiza might regula
te the plasma membrane ATPase by increasing the coupling efficiency between
H+ transport and ATP hydrolysis. The observed effects of mycorrhizal colon
ization on plasma membrane H+-ATPase were independent of the AM fungal spec
ies colonizing the root system.