Detection of Ascorbate Peroxidase (APX) Activity in Plant Tissues: Using Non-denaturing PAGE and Spectrophotometric Assay

Abiotic stress-regulated LEA gene mediates the response to drought, salinity, and cold stress in Medicago sativa L

Late embryogenesis abundant (LEA) proteins are typical stress-related proteins widely distributed across various organisms. Their anti-stress functions in higher plants have garnered significant attention and have been extensively studied; however, no such studies have been reported on the entire protein family in Medicago sativa. In this study, we identified a total of 83 MsLEA proteins in M. sativa and conducted a comprehensive analysis to elucidate their functions in response to abiotic stresses. The results indicated that these proteins could be classified into seven groups and were distributed across eight chromosomes. Collineation analysis revealed that segmental duplication primarily drove the expansion of MsLEA genes. Furthermore, the promoters of MsLEA genes were found to be enriched with cis-acting elements associated with various stress responses. Through transcriptome and quantitative real-time PCR analysis, nine MsLEA genes related to drought, salinity, and cold stress were identified, with MsLEA69 selected for further validation. The ectopic expression of MsLEA69 improves osmotic and extreme temperature tolerance by increasing the activity of stress-related enzymes in both prokaryotic and eukaryotic cells. These comprehensive analyses and identifications lay the groundwork for future research into the functional mechanisms of MsLEA proteins and offer potential candidate genes for enhancing resistance breeding in M. sativa.

Vitamin C: From Self-Sufficiency to Dietary Dependence in the Framework of Its Biological Functions and Medical Implications

Vitamin C is an organic compound biosynthesized in plants and most vertebrates. Since its discovery, the benefits of vitamin C use in the cure and prevention of various pathologies have been frequently reported, including its anti-oxidant, anti-inflammatory, anticoagulant, and immune modulatory properties. Vitamin C plays an important role in collagen synthesis and subsequent scurvy prevention. It is also required in vivo as a cofactor for enzymes involved in carnitine and catecholamine norepinephrine biosynthesis, peptide amidation, and tyrosine catabolism. Moreover, as an enzymatic cofactor, vitamin C is involved in processes of gene transcription and epigenetic regulation. The absence of the synthesis of L-gulono-1,4-lactone oxidase, a key enzyme in the pathway of vitamin C synthesis, is an inborn metabolism error in some fishes and several bird and mammalian species, including humans and non-human primates; it is caused by various changes in the structure of the original GULO gene, making these affected species dependent on external sources of vitamin C. The evolutionary cause of GULO gene pseudogenization remains controversial, as either dietary supplementation or neutral selection is evoked. An evolutionary improvement in the control of redox homeostasis was also considered, as potentially toxic H2O2 is generated as a byproduct in the vitamin C biosynthesis pathway. The inactivation of the GULO gene and the subsequent reliance on dietary vitamin C may have broader implications for aging and age-related diseases, as one of the most important actions of vitamin C is as an anti-oxidant. Therefore, an important aim for medical professionals regarding human and animal health should be establishing vitamin C homeostasis in species that are unable to synthesize it themselves, preventing pathologies such as cardiovascular diseases, cognitive decline, and even cancer.

Antioxidant Responses and Redox Regulation Within Plant-Beneficial Microbe Interaction

The increase in extreme climate events associated with global warming is a great menace to crop productivity nowadays. In addition to abiotic stresses, warmer conditions favor the spread of infectious diseases affecting plant performance. Within this context, beneficial microbes constitute a sustainable alternative for the mitigation of the effects of climate change on plant growth and productivity. Used as biostimulants to improve plant growth, they also increase plant resistance to abiotic and biotic stresses through the generation of a primed status in the plant, leading to a better and faster response to stress. In this review, we have focused on the importance of a balanced redox status for the adequate performance of the plant and revisited the different antioxidant mechanisms supporting the biocontrol effect of beneficial microbes through the adjustment of the levels of reactive oxygen species (ROS). In addition, the different tools for the analysis of antioxidant responses and redox regulation have been evaluated. The importance of redox regulation in the activation of the immune responses through different mechanisms, such as transcriptional regulation, retrograde signaling, and post-translational modification of proteins, emerges as an important research goal for understanding the biocontrol activity of the beneficial microbes.