Antioxidant responses of peanut roots exposed to realistic groundwater doses of arsenate: Identification of glutathione S-transferase as a suitable biomarker for metalloid toxicity.

Arsenic (As)-polluted groundwater constitutes a serious problem for peanut plants, as roots can accumulate the metalloid in their edible parts. Characterization of stress responses to As may help to detect potential risks and identify mechanisms of tolerance, being the induction of oxidative stress a key feature. Fifteen-day old peanut plants were treated with arsenate in order to characterize the oxidative stress indexes and antioxidant response of the legume under realistic groundwater doses of the metalloid.

Induced systemic resistance and symbiotic performance of peanut plants challenged with fungal pathogens and co-inoculated with the biocontrol agent Bacillus sp. CHEP5 and Bradyrhizobium sp. SEMIA6144.

Synergism between beneficial rhizobacteria and fungal pathogens is poorly understood. Therefore, evaluation of co-inoculation of bacteria that promote plant growth by different mechanisms in pathogen challenged plants would contribute to increase the knowledge about how plants manage interactions with different microorganisms. The goals of this work were a) to elucidate, in greenhouse experiments, the effect of co-inoculation of peanut with Bradyrhizobium sp.

Dynamic responses of photosynthesis and the antioxidant system during a drought and rehydration cycle in peanut plants.

Drought stress is one of the most important environmental factors that adversely affect the productivity and quality of crops. Most studies focus on elucidating plant responses to this stress but the reversibility of these effects is less known. The aim of this work was to evaluate whether drought-stressed peanut (Arachis hypogaea L.

Influence of cadmium on the symbiotic interaction established between peanut (Arachis hypogaea L.) and sensitive or tolerant bradyrhizobial strains.

Heavy metals in soil are known to affect rhizobia-legume interaction reducing not only rhizobia viability, but also nitrogen fixation. In this work, we have compared the response of the symbiotic interaction established between the peanut (Arachis hypogaea L.) and a sensitive (Bradyrhizobium sp.

Contribution of phytochelatins to cadmium tolerance in peanut plants.

Cadmium (Cd) is a well known heavy metal considered as one of the most toxic metals on Earth, affecting all viable cells that are exposed even at low concentration. It is introduced to agricultural soils mainly by phosphate fertilizers and causes many toxic symptoms in cells. Phytochelatins (PCs) are non-protein thiols which are involved in oxidative stress protection and are strongly induced by Cd.

Production and function of jasmonates in nodulated roots of soybean plants inoculated with Bradyrhizobium japonicum.

Little is known regarding production and function of endogenous jasmonates (JAs) in root nodules of soybean plants inoculated with Bradyrhizobium japonicum. We investigated (1) production of jasmonic acid (JA) and 12-oxophytodienoic acid (OPDA) in roots of control and inoculated plants and in isolated nodules; (2) correlations between JAs levels, nodule number, and plant growth during the symbiotic process; and (3) effects of exogenous JA and OPDA on nodule cell number and size. In roots of control plants, JA and OPDA levels reached a maximum at day 18 after inoculation; OPDA level was 1.

Importance of glutathione in the nodulation process of peanut (Arachis hypogaea).

GSH appears to be essential for proper development of the root nodules during the symbiotic association of legume-rhizobia in which the entry of rhizobia involves the formation of infection threads. In the particular case of peanut-rhizobia symbiosis, the entry of rhizobia occurs by the mechanism of infection called 'crack entry', i.e.

Changes in ligno-suberization of cell walls of tomato hairy roots produced by salt treatment: the relationship with the release of a basic peroxidase.

A highly basic peroxidase isoenzyme was shown to be released to the culture medium of tomato (Lycopersicon esculentum) hairy roots grown in Murashige-Skoog (MS) liquid medium when it was supplemented with 100 mM NaCl. In this paper we demonstrate that this enzyme is ionically bound to cell walls and that the release was a consequence of the continuous agitation of the tissue in a high ionic strength medium with salt addition. In order to establish the physiological role of this isoenzyme we partially purified it, and we analysed its kinetic properties as coniferyl alcohol peroxidase.