Psittacanthus calyculatus is a hemiparasite mistletoe that represents an ecological problem due to the impacts caused to various tree species of ecological and commercial interest. Although the life cycle for the Psittacanthus genus is well established in the literature, the development stages and molecular mechanism implicated in P. calyculatus host infection are poorly understood. In this study, we used a manageable infestation of P. laevigata with P. calyculatus to clearly trace the infection, which allowed us to describe five phenological infective stages of mistletoe on host tree branches: mature seed (T1), holdfast formation (T2), haustorium activation (T3), haustorium penetration (T4), and haustorium connection (T5) with the host tree. Proteomic analyses revealed proteins with a different accumulation and cellular processes in infective stages. Activities of the cell wall-degrading enzymes cellulase and β-1,4-glucosidase were primarily active in haustorium development (T3), while xylanase, endo-glucanase, and peptidase were highly active in the haustorium penetration (T4) and xylem connection (T5). Patterns of auxins and cytokinin showed spatial concentrations in infective stages and moreover were involved in haustorium development. These results are the first evidence of proteins, cell wall-degrading enzymes, and phytohormones that are involved in early infection for the Psittacanthus genus, and thus represent a general infection mechanism for other mistletoe species. These results could help to understand the molecular dialogue in the establishment of P. calyculatus parasitism.

Psittacanthus calyculatus parasitizes mesquite trees through a specialized structure called a haustorium, which, in the intrusive process, can cause cellular damage in the host tree and release DAMPs, such as ATP, sugars, RNA, and DNA. These are highly conserved molecules that primarily function as signals that trigger and activate the defense responses. In the present study, we generate extracellular DNA (exDNA) from mesquite (P. laevigata) tree leaves (self-exDNA) and P. calyculatus (non-self exDNA) mistletoe as DAMP sources to examine mesquite trees’ capacity to identify specific self or non-self exDNA. We determined that mesquite trees perceive self- and non-self exDNA with the synthesis of O^2•−, H₂O₂, flavonoids, ROS-enzymes system, MAPKs activation, spatial concentrations of JA, SA, ABA, and CKs, and auxins. Our data indicate that self and non-self exDNA application differs in oxidative burst, JA signaling, MAPK gene expression, and scavenger systems. This is the first study to examine the molecular biochemistry effects in a host tree using exDNA sources derived from a mistletoe.

Stressed organisms identify intracellular molecules released from damaged cells due to trauma or pathogen infection as components of the innate immune response. These molecules called DAMPs (Damage-Associated Molecular Patterns) are extracellular ATP, sugars, and extracellular DNA, among others. Animals and plants can recognize their own DNA applied externally (self-exDNA) as a DAMP with a high degree of specificity. However, little is known about the microalgae responses to damage when exposed to DAMPs and specifically to self-exDNAs. Here we compared the response of the oilseed microalgae Neochloris oleoabundans to self-exDNA, with the stress responses elicited by nonself-exDNA, methyl jasmonate (MeJA) and sodium bicarbonate (NaHCO₃). We analyzed the peroxidase enzyme activity related to the production of reactive oxygen species (ROS), as well as the production of polyphenols, lipids, triacylglycerols, and phytohormones. After 5 min of addition, self-exDNA induced peroxidase enzyme activity higher than the other elicitors. Polyphenols and lipids were increased by self-exDNA at 48 and 24 h, respectively. Triacylglycerols were increased with all elicitors from addition and up to 48 h, except with nonself-exDNA. Regarding phytohormones, self-exDNA and MeJA increased gibberellic acid, isopentenyladenine, and benzylaminopurine at 24 h. Results show that Neochloris oleoabundans have self-exDNA specific responses.

This study investigates the incorporation of melanin extracted from pecan nutshell residues into a polyacrylonitrile (PAN) matrix during the electrospinning of microfiber membranes. Melanin concentrations of 0.5, 2.0, and 5.0% w/w were incorporated to enhance the physicochemical and biological properties of the fibers. The melanin-loaded PAN fibers exhibited significant antioxidant activity against DPPH and ABTS radicals, with scavenging rates ranging from 46.58% to 62.77% and 41.02% to 82.36%, respectively, while unmodified PAN fibers showed no activity. Furthermore, the melanin-loaded membranes demonstrated antimicrobial effects. The membranes also exhibited an important enzyme inhibition activity against collagenase (37%), hyaluronidase (22%), tyrosinase (36%), and elastase (33%). Molecular docking studies reveal different potential amino acids of the active sites of aging enzymes that interact strongly with melanin pigment, particularly collagenase, followed by hyaluronidase, tyrosinase, and elastase. These results suggest that the novel melanin-loaded PAN membranes possess promising bioactive properties with potential applications in different skin-care applications.

Objective: To compare the effects of applying an organic biofertilizer (APIS®), formulated from whey, on agronomic and biochemical variables in sweet potato (Ipomoea batatas).Design/Methodology/Approach: A randomized block design was implemented over a 1.5 ha open-field plot. Treatments included foliar applications of APIS®, Bayfolan Forte® (a commercial fertilizer), and water (as a control) at 35- and 65-days post-transplanting (dpt). Sampling was conducted at 35, 60, and 85 dpt to evaluate morphological parameters; quantification of total bacteria and filamentous fungi; elemental analysis; chlorophyll content; total protein; total polyphenols; soluble sugars; and hydrogen peroxide (H2O2) levels.Results: The organic biofertilizer APIS® led to a higher number of tubers and, consequently, greater yield per hectare 22% and 32% higher compared to Bayfolan Forte® and the control, respectively. APIS® also enhanced microbial load during the second sampling, followed by a reduction in the third. No statistically significant differences were observed between the APIS® and control treatments regarding morphological parameters, chlorophyll content, total protein, polyphenols, soluble sugars, and H2O2. However, H2O2 concentrations increased in the Bayfolan Forte® treatment compared to the control.Limitations/Implications: The study was conducted during a single agricultural cycle, which may limit broader generalizations.Findings/Conclusions: APIS® demonstrates potential as a viable biofertilizer for sweet potato cultivation,showing comparable or superior performance to the commercial fertilizer.