Azospirillum brasilense respondes to water deficit adjusting lipid composition

CESARI A; REGUERA Y.B.; PAULUCCI N.S.; KILMURRAY C; DARDANELLI M.S

Mar del Plata

Congreso; LI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2015

SAIB

Azospirillum is a rhizobacteria studied for its ability to improve growth and performance of many crop by alleviatingstresses. We studied A. brasilense tolerance to water deficit and the dynamics of adaptive process at the membranelevel. A. brasilense was exposed to polyethylene glycol 15 mM (PEG) growth and PEG shock (10, 20, 30 and 60min). Membrane fluidity was determined by measuring fluorescence polarization of DPH. Lipids were extracted. Thefatty acids (FA) were analyzed by GC. Identification of phospholipids (PL) was performed using TLC. For itsquantification, [1-14C] sodium acetate was added to culture. A. brasilense viability was reduced in presence of PEG.Cells grown with PEG showed membrane fluidity similar to those grown without. Lipid composition was modified,increasing phosphatidylcholine and decreasing phosphatidylethanolamine amounts. The unsaturation FA degree wasreduced. The fluidity decrease 20 min after the addition of PEG, indicating that the PEG has a fluidizing membraneeffect. Fluidity returned to initial values after 60 min of PEG exposure. We conclude that A. brasilense perceiveosmotic changes by changing membrane fluidity. This effect is offset by changes in PL and FA composition,contributing to the homeostasis of membrane fluidity under water deficit. This knowledge can be used to developnew A. brasilense formulations applied to water deficit.