The effect of nitric oxide on heme oxygenase gene expression in soybean leaves

NORIEGA, GUILLERMO; YANNARELLI, GUSTAVO; BALESTRASSE, KARINA; BATLLE, ALCIRA; TOMARO, MARÍA LUJÁN

PLANTA

Springer-Verlag

Año: 2007 vol. 226 p. 1155 - 1163

0032-0935

Heme oxygenase (HO, EC 1.14.99.3) catalyzes the oxidative conversion of heme to biliverdin IXa with the concomitant release of carbon monoxide and iron. Recently, HO has been involved in the protection against oxidative stress in plants. The fact that nitric oxide (NO), an endogenous signaling molecule in animals and plants mediates responses to abiotic and biotic stresses, prompted gene transcription. To fulfill this objective leaves of soybean (Glycine max L.) plants were stimulated with Cd, employing an acute intoxication model. Cadmium caused dehydration, chlorophyll loss and ion leakage. Semiquantitative RT-PCR analysis showed no augmentation of HO-1 transcript levels with respect to controls. Pretreatment with 100 lM sodium nitroprussiate (SNP), a wellknown NO donor, prevented the effects caused by Cd.When the HO-1 mRNA levels were analyzed, a significant augmentation (54%) was observed with respect to Cdtreated plants. On the other hand, 50 or 300 lM SNP did not fully prevent the effects elicited by Cd. When HO-1 transcript levels were analyzed, no significant enhancement or a down-regulation was observed. The potassium salt of 2-(4-carboxylphenyl)-4,4,5,5-tetramethylimidazoline-1- oxyl-3-oxide (cPTIO), a specific NO scavenger, arrested NO-mediated protective effects against to Cd-induced oxidative damage. These data provide an understanding of one of the possible roles that NO can play against an oxidative insult. NO is cytoprotective depending on its concentration, and it was further demonstrated that this protection could be, at least in part, mediated by an enhancement of HO-1 mRNA, as it happens with genes associated with the antioxidant defense system.