Response of soybean nodules to exogenously applied caffeic acid during NaCl-induced salinity

AbstractCaffeic acid acts as an antioxidant to scavenge reactive oxygen species, but its influence on plant responses to abiotic stresses is only partially understood. Here, we investigated the influence of exogenously applied caffeic acid on soybean during NaCl-induced salinity. Exogenously applied caffeic acid reduced the deleterious effects of salinity stress on soybean plants and increased nitric oxide content in root nodules and this corresponded with elevated cyclic guanosine monophosphate content in the nodules. Salinity stress reduced nodule legheamoglobin content and nitrogenase activity whereas exogenous application of caffeic acid to NaCl-treated plants reversed these negative effects of NaCl on legheamoglobin content and nitrogenase activity. Hydrogen peroxide (H2O2) and malondialdehyde contents in soybean root nodules from plants exposed to salinity were lower when these plants were supplemented with exogenous caffeic acid than when no caffeic acid was supplemented. We suggest that caffeic acid enhances nitric oxide biosynthesis, which possibly acts to reduce salinity-induced oxidative stress through a mechanism that involves nitric oxide signaling coupled with cyclic guanosine monophosphate-mediated signaling to scavenge reactive oxygen species.The ability of caffeic acid to reduce salinity-induced oxidative stress via regulation of nitric oxide signaling has implications for genetic improvement of crop to enhance their tolerance against salinity. This can be achieved by identifying genes, namely genes encoding p-coumarate 3-hydroxylases, responsible for the biosynthesis of caffeic acid and modulating their expression under salinity. Such improvement would impact positively on food security as it would limit the detrimental effects of salinity of crop productivity

Fungal‑derived compounds and mycogenic nanoparticles with antimycobacterial activity: a review

Tuberculosis (TB) is a persistent lung infection caused by Mycobacterium tuberculosis. The disease is characterized by high mortality rates of over 1 million per year. Unfortunately, the potency and efectiveness of currently used anti-TB drugs is gradually decreasing due to the constant development of persistence and resistance by M. tuberculosis. The adverse side efects associated with current anti-TB drugs, along with anti-TB drug resistance, present an opportunity to bioprospect novel potent anti-TB drugs from unique sources. Fundamentally, fungi are a rich source of bioactive secondary metabolites with valuable therapeutic potential. Enhancing the potency and efectiveness of fungal-based anti-TB drug leads by chemical synthesis and/or modifcation with nanomaterials, may result in the discovery of novel anti-TB drugs. In this review, the antimycobacterial activity of fungal-derived compounds and mycogenic nanoparticles are summarized. Numerous fungal-derived compounds as well as some mycogenic nanoparticles that exhibit strong antimycobacterial activity that is comparable to that of approved drugs, were found. If fully explored, fungi holds the promise to become key drivers in the generation of lead compounds in TB-drug discovery initiatives

Farmers’ Knowledge, Perceptions and Attitudes on Crop-Dairy Goat Integration Farming System in Elgeyo Marakwet County

Several interventions have been promoted in dry areas to improve food and nutrition insecurity. However, studies on the key drivers influencing adoption and uptake are limited. Therefore, research was undertaken to investigate farmers’ knowledge, perceptions and attitudes on an integrated crop–dairy goat farming system in Elgeyo Marakwet. A cross-sectional study entailing a household survey of 201 respondents, six key informant interviews and eight focus group discussions was undertaken. This study utilized a multi-stage sampling procedure to sample the farmers and calculated the sample size using Krejcie and Morgan tables. Quantitative data were subjected to descriptive and inferential statistics using SPSS software version 22, while qualitative data were analysed using N-vivo software version 10 through the Framework Analysis method. The findings show that drought (84.6%), change in rainfall pattern (77.6%), farm size (57.2%), unavailability of quality seeds (52.2%), fodder acreage (58.7%), diseases (69.7%) and pest severity (68.7%) are the principal drivers for adoption of the integrated crop–dairy goat farming system. Dairy goats are associated with women in this community since they are regarded as small animals and have no monetary value, hence increasing the participation of women in the access, control and decision making of agricultural resources. To increase adoption, strategies focusing on improving water supply, quality seeds, agro-veterinary services and production are advocated

Modulation of antioxidant enzyme activities and metabolites ratios by nitric oxide in short-term salt stressed soybean root nodules

Several abiotic factors cause molecular damage to plants either directly or through the accumulation of reactive oxygen species such as hydrogen peroxide (H2O2). We investigated if application of nitric oxide (NO) donor 2,2′- (hydroxynitrosohydrazono) bis-ethanimine (DETA/NO) could reduce the toxic effect resulting from short-term salt stress. Salt treatment (150 mM NaCl) alone and in combination with 10 μM DETA/NO or 10 μM DETA were given to matured soybean root nodules for 24 h. Salt stress resulted in high H2O2 level and lipid peroxidation while application of DETA/NO effectively reduced H2O2 level and prevented lipid peroxidation in the soybean root nodules. NO treatment increased the activities of ascorbate peroxidase and dehydroascorbate reductase under salt stress. Whereas short-term salt stress reduced AsA/DHAsA and GSH/GSSG ratios, application of the NO donor resulted in an increase of the reduced form of the antioxidant metabolites thus increasing the AsA/DHAsA and GSH/GSSG ratios. Our data suggests a protective role of NO against salt stress.Web of Scienc

Endogenous NO levels regulate nodule functioning: Potential role of cGMP in nodule functioning?

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Effect of exogenous application of nitric oxide on salt stress responses of soybean

AbstractSalinity stress is one of the major factors that reduce annual agricultural produce. This has led to numerous studies investigating means to improve tolerance to salt stress. Nitric oxide (NO) is a gaseous signaling molecule involved in the regulation of diverse processes in plants. Certain studies have demonstrated the role of exogenous application of NO in mediating responses to abiotic stress. We investigated the role of exogenously applied NO 2,2′(hydroxynitrosohydrazono) bis-ethanimine (DETA/NO) in ameliorating long term salinity stress on soybean. Long term salinity stress in the form of a final concentration of 80mM sodium chloride (NaCl) over a 16day period drastically affected the plants as indicated by decreased biomass of shoots, roots and nodules of soybean plants. In contrast, supplementation with 10μM DETA/NO improved growth of soybean plants under NaCl as evidenced by increased shoot, root and nodule weights and nodule number. Further analysis showed that long-term salinity stress led to increased cellular hydrogen peroxide (H2O2) content and high levels of cell death in the soybean. Treatments with NO, either as DETA/NO alone or in combination with NaCl, resulted in reversal of H2O2 to basal levels. This study showed that application of DETA/NO resulted in increased enzymatic activity of ascorbate peroxidase (APX). We propose that the role of NO in increasing tolerance to salinity stress in soybean may result from either its antioxidant capacity by direct scavenging of H2O2 or its role in activating APX activity that is crucial in scavenging H2O2

Nitric oxide increases the enzymatic activity of three ascorbate peroxidase isoforms in soybean root nodules

Ascorbate peroxidase is one of the major enzymes regulating the levels of H2O2 in plants and plays a crucial role in maintaining root nodule redox status. We used fully developed and mature nitrogen fixing root nodules from soybean plants to analyze the effect of exogenously applied nitric oxide, generated from the nitric oxide donor 2,2′-(hydroxynitrosohydrazono)bis-ethanimine, on the enzymatic activity of soybean root nodule ascorbate peroxidase. Nitric oxide caused an increase in the total enzymatic activity of ascorbate peroxidase. The nitric oxide-induced changes in ascorbate peroxidase enzymatic activity were coupled to altered nodule H2O2 content. Further analysis of ascorbate peroxidase enzymatic activity identified three ascorbate peroxidase isoforms for which augmented enzymatic activity occurred in response to nitric oxide. Our results demonstrate that nitric oxide regulates soybean root nodule ascorbate peroxidase activity. We propose a role of nitric oxide in regulating ascorbate-dependent redox status in soybean root nodule tissue. © 2011 Landes Bioscience.Articl

Capacity to control oxidative stress-induced caspase-like activity determines the level of tolerance to salt stress in two contrasting maize genotypes

The response of two maize (Zea mays L.) genotypes, named GR (salt-tolerant) and SK (salt-sensitive), to salt stress (150 mM NaCl) was investigated under controlled environmental growth conditions. Genotype SK experienced more oxidative damage than the GR genotype when subjected to salt stress, which corresponded to higher O2 - production rate and H2O2 content in the SK genotype than the GR genotype. Induction of caspase-like activity in response to salt stress was stronger in the SK genotype than in the GR genotype. On the other hand, induction of antioxidant enzyme activity to scavenge O2 - and H2O2 in response to salt stress was weaker in the SK genotype than in the GR genotype. Consequently, the higher level of oxidative damage in the SK genotype in response to salt stress was manifested as more extensive cell death and biomass reduction in the SK genotype than it was in the GR genotype. Our results suggest that a direct relationship exists between salt stress-induced oxidative damage and cell death-inducing caspase-like activity, with tolerance to the salt stress being controlled by the efficiency of the plant antioxidant enzymes in limiting salt stress-induced oxidative damage and thus limiting cell death-inducing caspase-like activity. © 2012 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków