Nostoc sp. extract induces oxidative stress-mediated root cell destruction in Mimosa pigra L

Study of pesticidal activity of bioactive compounds of Neowestiellopsis persica strain A1387 in improving the antioxidative and antimicrobial activity of wheat to sunn pest

Cyanobacteria have been recognized for their advantageous impact on plant growth and development. The application of certain techniques has the potential to enhance various aspects of plant development, including growth, yield, proximate content (such as protein and carbohydrate levels), as well as the ability to withstand abiotic stresses such as herbicide exposure. The current investigation focused on examining the influence of bioactive compounds derived from the cyanobacterium Neowestiellopsis persica strain A1387 on enhancing the antioxidant and anyimicrobial activity of wheat plants in their defense against the plant pathogenic Sunn pest. The findings of the study indicate that the levels of H2O2 and GPx in wheat plants that were infected with aphids were significantly elevated compared to the treatments where aphids and cyanobacteria extract were present. The confirmation of these results was achieved through the utilization of confocal and fluorescent microscope tests, respectively. Furthermore, the findings indicated that the constituents of the cyanobacterial extract augmented the plant's capacity to withstand stress by enhancing its defense mechanisms. In a broader context, the utilization of cyanobacterial extract demonstrated the ability to regulate the generation and impact of oxygen (O2) and hydrogen peroxide (H2O2), while concurrently enhancing the functionality of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) enzymes within wheat plants. This facilitation enabled the plants to effectively manage oxidative stress. Moreover, the findings of the antibacterial activity assessment conducted on the extract derived from cyanobacteria demonstrated notable susceptibility. The bacteria that exhibited the highest sensitivity to the extract of cyanobacterium Neowestiellopsis persica strain A1387 were staphylococcus aureus and pseudomonas aeruginosa. Conversely, salmonella typhi demonstrated the greatest resistance to the aforementioned extract. The potential impact of cyanobacteria extract on the antioxidative response of wheat plants to sunn pest infestation represents a novel contribution to the existing body of knowledge on the interaction between wheat plants and aphids.

Nostoc entophytum cell response to cadmium exposure: A possible role of chaperon proteins GroEl and HtpG in cadmium-induced stress

The present study is pursuing our previous research, focused on some aspects of Nostoc entophytum ISC32 cell response to the stress caused by exposure to cadmium at the cellular and molecular levels. Variations in the antioxidant system (catalase and ascorbate peroxidase activity) of N. entophytum ISC32 exposed to varying concentrations of Cd (2, and 5 mg/L) resulted in a significant increase in the activity of both catalase and peroxidase. Activity of these enzymes was, however, not significantly changed in the presence of Cd concentrations of 10 and 20 mg/L. Levels of lipid peroxidation, as measured by malondialdehyde (MDA) assay, were observed in response to exposure to Cd (20 mg/L). There was, however, a sharp drop in both antioxidant and lipid peroxidation activities of Cd treated cells after 5 days exposure, likely in consequence of cellular damage. The content of chlorophyll a and phycobiliproteins of living cells were altered under Cd-induced conditions. TEM images of cyanobacterial cells treated with Cd showed cell surface alteration and modification along with altered cellular microcompartments. Cyanobacterial cells treated with Cd at concentrations below the minimum inhibitory concentration (MIC) remained with no apparent structural changes. However, at a higher concentration of Cd (30 mg/L), a clear detachment effect was observed between the mucilage external layer and cell membrane which may be attributed to cell plasmolysis due to toxic effects of Cd. Subsequently, the thickness of the ring-shaped mucilage external layer increased likely as a result of the cell defense mechanisms against toxic concentrations of Cd. Characterization of cells treated with Cd (30 and 150 mg/L) by scanning electron microscopy (SEM) indicated cell shrinkage with varying degrees of distortion and surface wrinkling. Energy-dispersive X-ray spectrometry (EDS) analysis suggested that Cd was not present as nanoparticles within the cell, but in the form of salt or other molecular structures. The up-regulation of chaperons was confirmed for GroEL and HtpG using real-time PCR and northern blot analyses. Interestingly, the expression of GroEL was markedly increased at lower Cd concentration (5 mg/L). However, the ISC32 strain accrued higher levels of HtpG transcript in response to an elevated concentration of Cd (15 mg/L). This pattern seems to be related to the fast and early induction of GroEL, which may be necessary for induction of other factors and heat shock proteins such as HtpG in Cd-treated Nostoc cells. The result of this study paves the way for a more detailed exploration of Cd effects on the defense mechanisms of cyanobacteria. Our research also shed some light on how cyanobacterial cells have evolved to respond to the heavy metal toxicity at the cellular, molecular and ultrastructural levels.

Nostoc calcicola extract improved the antioxidative response of soybean to cowpea aphid

BACKGROUND

Soybean (Glycine max (L.) Merr. cv. "Nam Dan") is one of the most valuable crops in agricultural production in Nghe An province (Vietnam). Our previous study revealed that extract of the cyanobacterium strain Nostoc calcicola HN9 expressed positive effect on growth and development, and raised soybean productivity (Tran et al. in Proceeding of Vietnam national conference of research on biology, Da Nang, 2016). We hypothesized that N. calcicola HN9 would improve the defense responses of G. max cv. "Nam Dan" to cowpea aphid (Aphis craccivora Koch)-a serious pest of leguminous crops.

RESULTS

Infestation of A. craccivora caused oxidative stress in leaves of G. max cv. "Nam Dan". A strong generation of endogenous reactive oxygen species (ROS) such as superoxide anion radical (O ₂^·- ) and hydrogen peroxide (H₂O₂) resulted in the cellular damages in the aphid-infested leaves through high levels of injury percentage and lipid peroxidation. To protect from aphid attack themselves, soybean plants triggered the antioxidant defense systems, in which, enzymatic antioxidants such as superoxide dismutase (SOD, 1.15.1.1), catalase (CAT, 1.11.1.6) and GPx (EC 1.11.1.9) were strongly accumulated to reduce the toxic effects of ROS. Components of N. calcicola HN9 extract might strengthen the defensive capability of G. max cv. "Nam Dan" to cowpea aphid infestation via establishing the chemical constraints on oxidative stress. Under effect of cyanobacteria extract, generation of O ₂^·- and H₂O₂ was strictly limited, activities of SOD, CAT and GPx were remarkably accumulated in the aphid-infested leaves leading to a significant reduction of oxidative damages.

CONCLUSIONS

Nostoc calcicola HN9 extract probably not only controlled the generation and effects of O ₂^·- and H₂O₂ but also augmented the accumulated activity of SOD, CAT and GPx in soybean leaves that allowed them to control oxidative stress, contributed to increase the resistance of G. max cv. "Nam Dan" to A. craccivora. The improvement of cyanobacteria extract on the antioxidative response of soybean "Nam Dan" to cowpea aphid can be a novel aspect to contribute to current knowledge regarding the soybean-aphid interaction.