Humic substances have been widely used as plant growth promoters to improve the yield of agricultural crops. However, the mechanisms underlying this effect remain unclear. Root soluble protein profiles in plants 11 days after planting and cultivated with and without humic acids (HA, 50 mg CL⁻¹), were analyzed using the label-free quantitative proteomic approach. Cultivation of maize with HA resulted in higher fresh weight of roots than in untreated plants (control). Plants treated with HA showed increased number, diameter and length of roots. In the proteomics analysis, differences were detected in the following categories: energy metabolism, cytoskeleton, cellular transport, conformation and degradation of proteins, and DNA replication. Thirty-four proteins were significantly more abundant in the seedlings treated with HA, whereas only nine proteins were abundant in the control. The effects on root architecture, such as the induction of lateral roots and biomass increase were accompanied by changes in the energy metabolism-associated proteins. The results show that the main effect of HA is protective, mainly associated with increased expression of the 2-cys peroxidase, putative VHS/GAT, and glutathione proteins. Indeed, these proteins had the highest fold-difference. Overall, these results improve our understanding of the molecular mechanisms of HA-promoted plant growth.

This work aimed to evaluate the phytoremediation capacity of the alfalfa cultivar Crioula in soils contaminated with polycyclic aromatic hydrocarbons (PAHs), primary pollutants with mutagenic and carcinogenic potential. Alfalfa was grown from seed for 40 days on soil amended with anthracene, pyrene, and phenanthrene. Soil and plant tissue was collected for biometric assay, dry mass analysis, and PAH analysis by liquid chromatography. Increased total PAH concentration was associated with decreases in plant biomass, height, and internode length. The Crioula cultivar had a satisfactory phytoremediation effect, reducing total PAH concentration (300 ppm) in the experimental soil by 85% in 20 days, and by more than 95% in 40 days. The PAH showed a tendency to be removed in the temporal order: phenanthrene before pyrene before anthracene, and the removal ratio was influenced by the initial soil concentration of each PAH. GRAPHICAL ABSTRACT Extracts containing PAH were obtained from soils cultivated with Medicago sativa L. (cv. Crioula) in the presence and absence of 150, 300, and 450 ppm total of PAH (phenanthrene, anthracene, and pyrene). After ultrasonication steps and purification of PAH by silica adsorption chromatography, samples containing PAH were quantified by high-performance liquid chromatography in reverse phase. At the end of this study, it was determined that the cv. Crioula showed a satisfactory phytoremediation potential. It presented the reduction of the total of PAH at around 85% in 20 days.

Human colostrum is recognized as a source of bioactive compounds that impact on neonatal development, such as antimicrobial peptides. Antimicrobial peptides (AMPs) present some common characteristics, as they are relatively small (<10 kDa), most of them are positively charged and possess α-helical regions. These molecules can protect the newborn against infectious agents such as bacteria, fungi, and viruses. Using an MS- based proteomic approach combined with the application of bioinformatic tools, 29 peptide sequences from human colostrum were annotated in human colostrum. These peptides are potentially antifungal and were enriched in glutamic acid (E), phenylalanine (F), lysine (K) and tryptophan (W) residues. Among the precursor proteins, two have a known 3D structure and their fragments are located in the protein core. In addition, in silico analyses revealed that AMPs containing regions of α-helix and random structures, and high aliphatic index (mean of 85.29) tend to be thermostable. In this work with human colostrum, previously unreported peptides with potential antimicrobial activity were annotated and structurally characterized via bioinformatic tools.