Strong growth inhibition under Na2SO4 salinization in the halophyte Prosopis strombulifera is related to changes in PSII proteins

REGINATO , MARIANA ANDREA; TURCIOS, ARIEL E.; PAPENBROCK, JUTTA

Congreso; XXXIII Argentinian meeting of Plant Physiology (RAFV2021); 2021

Sociedad Argentina de Fisiología Vegetal

Prosopis strombulifera (Lam.) Benth. is a halophytic shrub found in highly saline soils in Argentina and Chile, with high tolerance against NaCl but strong growth inhibition by Na2SO4. In the present study, the differences in growth response, ABA levels and PSII proteins caused by NaCl, Na2SO4 and the iso-osmotic combination were analyzed. Na2SO4-treated plants were the most affected by salinity, showing a significant decrease in several growth parameters with visible toxicity symptoms: chlorosis, necrosis and, finally, leaf abscission at high salinity (Ψo = -2.6 MPa). Accordingly, Na2SO4-treated plants showed the highest leaf ABA levels, with a significant increase in the three osmotic potentials tested (-1.9, -2.24, and -2.6 MPa), in relation to control and the other salt treatments. Western Blot analysis indicated important differences in the composition of PSII and related proteins between the different saline treatments. Important changes were observed in the Lhcb2 (LHCII type II chlorophyll a/b-binding protein), PsbA / D1(Protein Photosystem II protein D1) and PsbH (Photosystem II reaction center protein H) proteins in plants treated with Na2SO4. These changes were in correlation with the evaluated photosynthetic parameters and the strong growth inhibition observed in these plants. The results show for the first time that the SO42- anion is triggering damage in the photosynthetic apparatus and consequently affecting the photosynthetic process, which may explain the strong growth inhibition in these plants at high salinity.