Heme oxygenase is involved in the growth of soybean plants

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

Miami Beach, Florida, USA

Congreso; 6th INTERNATIONAL CONFERENCE ON HEME OXYGENASES. HEME OXYGENASES IN BIOLOGY AND MEDICINE Congress; 2009

A. Agarwal Chair, J. Alam Co-Chair, K.A. Nath, Co-Chair

The role of 5-aminolevulic acid (ALA) as an herbicide is well documented. Nevertheless, this compound has some promoter effects on the growth of several crops at low concentrations. The aim of this study was to evaluate in soybean plants, whether there is a relationship between the beneficial actions of ALA and heme oxygenase (HO) behaviour. To fulfil this purpose plants were treated with ALA concentrations ranging from 0-6 mM for 72 h. Twenty days after treatment, HO activity and protein levels were assessed. To evaluate oxidative damage, ion leakage (IL), chlorophyll (Chl) contents, as well as catalase (CAT) and superoxide dismutase (SOD) activities were determined. The amount of indolacetic acid (AIA), a well known growth hormone was also evaluated. Ion leakage parameters were not affected at all studied ALA concentrations. Chlorophyll content only augmented (52%) in plants treated with 6 µM ALA. An increase in CAT activity (32%) occurred under 6µM ALA, and no significant changes were observed in SOD activities. Heme oxygenase-1 activity was enhanced (25% and 52%) under 3 and 6 µM ALA respect to controls. These augmentations were confirmed by western blotting. Indolacetic acid was also increased with ALA treatment in a dose depending manner. When plants were pretreated with ZnPPIX oxidative stress occurred as demonstrated by IL and Chl contents as well as CAT and SOD activities. Moreover, AIA content diminished dramatically (70% respect to controls). Taking together these results indicate that HO-1 is involved in plant growth promoted by low ALA concentrations.