Monitoring expression profiles of antioxidant genes to salinity, iron, oxidative, light and hyperosmotic stresses in the highly salt tolerant grey mangrove, Avicennia marina (Forsk.) Vierh. by mRNA analysis

Abstract

Plant photosynthesis results in the production of molecular oxygen. An inevitable consequence of this normal process is the production of reactive oxygen species (ROS) by the transfer of electrons to molecular oxygen. Plants are adequately protected by the presence of multiple antioxidative enzymes in different organelles of the plant such as chloroplasts, cytosol, mitochondria and peroxisomes. Under high light and CO(2) limiting conditions caused by environmental stress like salinity, these antioxidative enzymes play an important role in scavenging toxic radicals. To investigate the functions of antioxidative enzymes in a mangrove plant, we isolated three cDNAs encoding cytosolic Cu-Zn SOD (Sod1), catalase (Cat1) and ferritin (Fer1) from Avicennia marina cDNA library. Sod1, Cat1 and Fer1 cDNA encoded full-length proteins with 152, 492 and 261 amino acids respectively. We studied the expression of these antioxidant genes in response to salt, iron, hydrogen peroxide, mannitol and light stress by mRNA expression analysis. Cat1, Fer1 showed short-term induction while Sod1 transcript was found to be unaltered in response to NaCl stress. A decrease in mRNA levels was observed for Sod1, Cat1 while Fer1 mRNA levels remained unaltered with osmotic stress treatment. Sod1, Cat1 and Fer1 mRNA levels were induced by iron, light stress and by direct H(2)O(2) stress treatment, thus confirming their role in oxidative stress response.

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“…The accumulation of PtFer reached the peak at 24h when facing the high salinity challenge (40ppt) and then began to decline to a lower level ( Figure 5). The salinity inducible expression patten of PtFer was similar to the mangrove plant and pear (Pyrus pyrifolia) (Jithesh et al, 2006;. The ferritin expression level of those plants was increased high and then reduced in the later time of salinity stress, and the ferritin was deduced to contribute to stress defense or stress tolerance (Jithesh et al, 2006;.…”

Soil Quality of Die off and Die Back Mangrove Grown at Al-Jubail Area (Saudi Arabia) of the Arabian Gulf

“…The physical breakdown of the aggregates due to stresses temporarily promotes the interaction between microbes and organic C substrates initially protected within the macro aggregates [22,38] . This process leads to increased microbial oxidation of the organic C and subsequently deplete the soil organic C [23] .…”

“…The amount of CO 2 -C respired per unit microbial biomass C (qCO 2 ) was large in high oxidative soils under these stresses due to low microbial biomass C pool and low biological activity [14,38] . This inferred that for a given amount of organic C in soil, proportionally more C would be assimilated through microbial biomass with the high qCO 2 and the soils under stress would accumulate less C over time [6] .…”

“…Mangrove plants are diverse group of predominantly trees, shrubs, palms and ground ferns growing around the mean sea level in the marine intertidal zone along tropical and subtropical coasts [20] . The ecological functions of mangroves as land builder and coastline stabilizer are well known [33,38] . It is also known that mangroves are highly productive and provide suitable habitats, shelter, breeding sites and food source for various groups of fish and other coastal wildlife [37] .…”

“…Numerous researchers have conducted field surveys, observations and field and laboratory experiments to examine the factors influencing mangrove soil quality. These factors include: water and soil sulfide concentrations [21,25] , salinity [5,38] , anoxia and water logging [37,38] , light [34,38] , nutrient availability [23,38] ; and biotic interactions such as site-specific competition [4] and predation [11,21,22] . The Soil Quality (SQ) is a minimum dataset (MDS) of analytical biological, chemical and physical properties of field moist and air-dried soils.…”