PEPTIDI AD AZIONE FITOSANITARIA

PEPTIDI AD AZIONE FITOSANITARI

PEPTIDES SIMILAR TO THE NATURAL PEPTAIBOL TRICHOGIN GA IV WITH PHYTOSANITARY ACTIVITIES

The invention relates to new peptides and their use as pesticides. In particular, these peptides have been advantageously used for the treatment of vine peronospora (downy mildew)

Water-Soluble Trichogin GA IV-Derived Peptaibols Protect Tomato Plants From Botrytis cinerea Infection With Limited Impact on Plant Defenses

Peptaibols are non-ribosomal linear peptides naturally produced by a wide variety of fungi and represent the largest group of peptaibiotic molecules produced by Trichoderma species. Trichogin GA IV is an 11-residue lipopeptaibol naturally produced by Trichoderma longibrachiatum. Peptaibols possess the ability to form pores in lipid membranes or perturb their surface, and have been studied as antibiotics or anticancer drugs in human medicine, or as antimicrobial molecules against plant pathogens. When applied to plants, peptaibols may also elicit defense responses. A major drawback to the exploitation and application of peptaibols in agriculture is their poor water solubility. In a previous study, we designed water-soluble Lys-containing Trichogin GA IV analogs, which were able to inhibit the growth of several fungal plant pathogens in vitro. In the present study, we shed light on the mechanism underpinning their efficacy on plants, focusing on six Trichogin GA IV analogs. Our results highlighted peptide hydrophilicity, rather than helix stability, as the major determinant of their activity against B. cinerea infection in tomato leaves. The peptides showed preventive but not curative efficacy against infection, and lack of translaminar activity, with results reproducible on two tomato cultivars, Marmande and Micro-Tom. Reactive oxygen species (ROS) detection analysis in tomato and Arabidopsis, and expression of defense genes in tomato, highlighted a transient and limited impact of the peptides on the plant defense system. The treatment did not result in significant modulation of defense genes or defense priming. The antimicrobial effect thus emerges as the only mechanism behind the plant protection ability exerted by water-soluble Trichogin GA IV analogs, and limited effects on the plant metabolism are expected to occur

Efficacy of <i>Trichoderma longibrachiatum</i> Trichogin GA IV Peptaibol analogs against the Black Rot Pathogen <i>Xanthomonas campestris</i> pv. <i>campestris</i> and other Phytopathogenic Bacteria

Black rot caused by the Gram-negative bacterial pathogen Xanthomonas campestris pv. campestris (Xcc) is considered one of the most destructive diseases affecting crucifers. Xcc is a seedborne pathogen able to infect the host at any growth stage. The management of the pathogen mainly relies on the use of copper-based products with possible negative effects on human health and the environment. Searching for protection alternatives is crucial for achieving a sustainable management of Xcc. Trichoderma spp. has been largely used as a biocontrol agent against several phytopathogens. Among Trichoderma species, Trichoderma longibrachiatum produces the peptaibol trichogin GA IV, a secondary metabolite with antimicrobial activity against Gram-positive bacteria, as well as filamentous and yeast-like fungi. In this work, we tested, at micromolar concentrations, 25 synthetic analogs of the peptaibol trichogin GA IV for their bacteriostatic and bactericidal activity toward the bacterium Xcc. One of the most effective peptides (4r) was also tested against the Gram-negative bacteria Xanthomonas arboricola, Pseudomonas corrugata, Pseudomonas savastanoi pv. savastanoi, Agrobacterium tumefaciens, Ralstonia solanacearum, and Erwinia carotovora subsp. carotovora, as well as the Gram-positive bacterium Bacillus subtilis. The peptide 4r reduced black rot symptoms on cauliflower plants when administered both before and 24 h after inoculation with Xcc. The cytotoxic activity of the peptide 4r was also evaluated towards suspensions of tobacco cells by Evans Blue assay

Unstabilized DNA breaks in lymphocytes of patients with different subsets of systemic sclerosis

The clastogenic effects on DNA, proven by the presence of micronuclei (MN) and the protective cellular mechanisms normally used to stabilize DNA breaks were investigated in three subsets of patients with systemic sclerosis (SSc). The frequency of MN found in cultures of peripheral lymphocytes in patients with anticentromere and antitopoisomerase I antibodies was significantly higher than that in the control group. The group with anticentromere antibody showed a significantly higher frequency of MN than did the subjects with antitopoisomerase antibody (4.22% versus 2.34%, P < 0.001). Patients with anti-RNA polymerase III, instead, had a low prevalence of typical micronucleated cells (0.98%), not significantly different from that of the healthy controls (0.82%). Moreover, when MN was characterized for the presence or absence of DNA fragments with free 3'-OH ends by digoxigenin-dUTP (DIG-dUTP) using terminal deoxynucleotidil transferase, its frequency was found to be increased in the groups with anticentromere and antitopoisomerase I antibodies with respect to that in the controls. The increase was significantly higher in the lymphocytes of the patients with anticentromere than in those with antitopoisomerase I antibody (35% versus 20.08%, P < 0.001). Nonetheless, the prevalence of unstable DNA fragments in patients with anti-RNA polymerase III antibody was low (2.05%) and not significantly different from that of the control group (1.18%). Our results indicate that there is a clastogenic effect on DNA and an interference in the protective cellular mechanisms normally stabilizing DNA breaks only in some subsets of SSc patients. The clastogenic effects on DNA, proven by the presence of micronuclei (MN), and the protective cellular mechanisms normally used to stabilize DNA breaks were investigated in patients with systemic sclerosis (SSc). The frequency of micronucleated cells found in cultures of peripheral lymphocytes in patients was significantly higher than in the control group. The patient group with anti-centromere antibodies showed a significantly higher frequency of micronucleated cells than that observed in the patients with anti-topoisomerase I antibodies (4.22% versus 2.34%, p < 0.001). Moreover, we attempted to characterize MN for the presence or absence of DNA fragments with free 3'-OH ends by digoxigenin-dUTP (DIG-dUTP) using terminal deoxynucleotidil transferase. It was found that the frequency of MN containing DNA fragments with 3'-OH free ends (unstable fragments) increased in SSc patients compared to that observed in the control group. Moreover, this increase was significantly higher in lymphocytes of the patients with anti-centromere antibodies than in those with anti-topoisomerase I antibodies (35% versus 20.08%, p < 0.001). Our results indicate that in SSc patients there is an interference in the protective cellular mechanisms, normally stabilizing DNA break