Drought-related changes in soluble and cell wall bound peroxidase activity from sunflower leaves.

LECHNER L; CREUS C; PINEDO M; AGUIRREZÁBAL L.A.N

Rosario

Congreso; Reunión Anual Sociedad Argentina de Investigación en Bioquìmica y Biologìa.; 2009

Sociedad Argentina de Investigación en Bioquìmica y Biologìa.

Extracellular peroxidases are enzymes that catalyzes the reduction of H2O2 with electrons transferred from a variety of molecules, classified as cell wall-bounded and soluble isoforms. They contribute to both the loosening and the stiffening of the cell wall, leading to opposite effects on growth. However, the precise role of apoplastic peroxidases in cell expansion has not been established. Furthermore, it is known that water stress reduces leaf growth and increases peroxidase activity. To assess the contribution of both isoforms to the observed inhibition of sunflower leaves growth in response to water deficit we isolated cell wall and extracellular fraction before the incubation with ferulic acid and tetrametilbencidine respectively in line HAR2 grown in chamber in well and stressed water conditions Leaf area was measured daily to cover different development stages. Soluble peroxidases activity increased after the end of leaf expansion both in control and water stressed plants. In contrast, cell wall-bound activity increased along with leaf growth, reaching a peak before the end of leaf expansion. In addition, water stress decreased soluble peroxidases compared to non-stressed plants while increased the activity of the cell wall-bound isoforms. These differential responses suggest a different and probably regulatory role for soluble and cell wall bound peroxidases in leaf expansion.