Nitric oxide-mediated antioxidant enzimes changes protect soybean leaves against UV-B radiation

SANTA CRUZ, DM; POLIZIO, AH; ZILLI, CG; YANNARELLI, GG; TOMARO ML.; BALESTRASSE, KB

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2012

In previous reports we demonstrated that heme oxygenase 1 (HO) plays a protective role against oxidative stress in soybean. Here we investigated the effect of nitric oxide (NO) on oxidative stress markers and classical antioxidant enzymes activities, isoform profile and gene expression in soybean leaves subjected to a high dose UV-B radiation (30 KJ m ). Pretreatments with 0.8 mM sodium nitroprussiate (SNP), a NO donor, applied as an spray prevented chlorophyll loss, H O and O . accumulation and ion leakage in UV-B-treated plants. The antioxidant response of plant leaves was evaluated analyzing the activities and isoform profile of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and unspecific peroxidases. UV-B treatment decreased CAT and APX specific activities 50 and 48 % respect to control values. On the other hand, we performed quantitative RT- PCR of HO, CAT, SOD and APX genes. UV-B treatment decreased significantly HO, CAT and APX gene expression levels, respect to control values. SNP pretreatments assays showed that NO reverts this response. SOD gene expression increased 2-fold respect to control. HO and CAT activities showed a positive correlation with HO-1 gene expression. Our results indicate that NO protects against high doses UV-B radiation by regulating the response of classical antioxidantenzymes