Effects of exogenous NO on antioxidant system of Taxus plants under simulated acid rain stress

Taxus is a famous medicinal and landscape tree species. The aim of this study was to explore the effect of exogenous nitric oxide (NO) on the resistance of Taxus plants to acid rain stress and to identify Taxus species with strong acid rain resistance by principal component analysis and comprehensive evaluation. In this study, sodium nitroprusside (SNP) was used as the exogenous NO donor. The effects of different SNP solution concentrations on the antioxidant systems of three Taxus species subjected to simulated acid rain stress (pH = 3.0) were compared. In order to achieve this goal, we determined the rate of O2- production, the ASA and GSH contents in leaves of three Taxus plants (Taxus mairei, Taxus chinensis, and Taxus yunnanensis). At the same time, the active leaves of some antioxidant enzymes (SOD, POD, CAT, APX and GR) were determined. For Taxus chinensis plants subjected to acid rain stress, treatment with an SNP concentration of 0.25 mmol·L-1 led to the most significant improvements in the antioxidant system. For Taxus mairei and Taxus yunnanensis, the treatment with the SNP concentration of 0.50 mmol·L-1 was best for improving their antioxidant systems under stress. Meanwhile, Taxus chinensis had the strongest resistance to simulated acid rain, followed by Taxus mairei and Taxus yunnanensis.

Earthworm and Arbuscular Mycorrhizal Fungi Improve Plant Hormones and Antioxidant Enzymes to Alleviate Simulated Acid Rain Stress

Aims Acid rain is considered one of the three most serious environmental disasters worldwide, disrupting the normal physiological metabolism of plants and inhibiting their growth. As important parts of soil biota community, both earthworms and arbuscular mycorrhizal fungi can promote the growth of plants under adverse conditions. However, whether them can improve the stress tolerance of plants under simulated acid rain stress remains to be explored.Methods Illumina high-throughput sequencing was used to conduct a relevant redundancy analysis (RDA) of soil microbial community structure and plant growth factors, and a structural equation model (SEM) was constructed for maize biomass and a biological index to study the mechanisms by which earthworms and mycorrhizal fungi affect maize stress resistance under simulated acid rain stress. Results Earthworms promoted the absorption of soil organic matter by maize; promoted the growth of the root system; and increased the hormone levels of GA3, ABA and IAA; ultimately improving the stress resistance of maize. Mycorrhizal fungi increased the relative abundance of plant growth-promoting rhizosphere bacteria, increased the levels of plant hormones and antioxidant enzymes, and improved the stress resistance of maize. Earthworms promoted infection by mycorrhizal fungi, and the interaction between earthworms and mycorrhizal fungi increased the root IAA content and the Shannon index of rhizosphere bacteria.Conclusions Both earthworms and mycorrhizal fungi can improve the stress resistance of maize through underground regulation. They interacted in increasing the root IAA content and the Shannon index of rhizosphere bacteria and alleviated the simulated acid rain stress of the aboveground part of the maize.