Behavior of soybean Heme Oxygenase subjected to UV-B radiation treatment

SANTA-CRUZ, DIEGO M.; BALESTRASSE, KARINA B.; POLIZIO, ARIEL H.; YANNARELLI, GUSTAVO G.; TOMARO, MARÍA L.

Tucumán, Argentina

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2009

SAIB

We have previously shown that heme oxygenase-1 (HO-1) plays a protective role against oxidative stress in soybean leaves subjected to UV-B radiation. The present study demonstrates that nitric oxide (NO) enhances this protection mechanism modulating HO-1 behavior. Pretreatments with 0.8-1.2 mM sodium nitroprussiate (SNP), an NO donor, prevented chlorophyll loss, H2O2 and O2.- accumulation and ion leakage in UV-B-irradiated plants (30 kJ m-2). Treatments with SNP enhanced HO-1 transcript levels after UV-B irradiation. Moreover, HO-1 mRNA was increased 2.1-fold in SNP-treated plants, whereas subsequent UV-B irradiation augmented this over-expression up to 3.5-fold with respect to controls. HO and catalase activities showed a positive correlation with HO-1 gene expression. cPTIO, an specific NO scavenger, negated the protection conferred by SNP. Findings here reported indicate that HO-1 over-expression involves NO and suggest that a balance between NO and ROS is required to trigger the expression of this antioxidant enzyme under UV-B radiation.