Peptide Design Principles for Antimicrobial Applications.

Peptides and small proteins exhibiting antimicrobial activity have been isolated from many organisms ranging from insects to humans, including plants. Their role in defense is established, and their use in agriculture was already being proposed shortly after their discovery. However, some natural peptides have undesirable properties that complicate their application. Advances in peptide synthesis and high-throughput activity screening have made possible the de novo and rational design of novel peptides with improved properties. This review summarizes findings in the identification and design of short antimicrobial peptides with activity against plant pathogens, and will discuss alternatives for their heterologous production suited to plant disease control. Recent studies suggest that peptide antimicrobial action is not due solely to microbe permeation as previously described, but that more subtle factors might account for the specificity and absence of toxicity of some peptides. The elucidation of the mode of action and interaction with microbes will assist the improvement of peptide design with a view to targeting specific problems in agriculture and providing new tools for plant protection.

Identification and Rational Design of Novel Antimicrobial Peptides for Plant Protection

Antimicrobial peptides (APs) have been described as evolutionary ancient weapons. Produced by a wide variety of organisms as part of a non-specific immune response, these peptides are involved in the direct destruction of various microorganisms. Several APs have been shown to have broad activity spectra against microorganisms such as Gram-positive and Gram-negative bacteria, enveloped viruses, fungi and parasites. Given that resistance to a number of antibiotics has developed in a wide range of microbes, the potential of APs as novel therapeutic agents is being evaluated. However, optimisation of APs designed for therapy will need to focus on such factors as their susceptibility to proteolytic degradation and reduction of toxicity to mammalian cells. Strict guidelines pertaining to their use should also be established to prevent or hinder future development of bacterial resistance to such peptides.

/pdf/antimicrobial-peptides-promising-alternatives-to-yjjffzhmui.pdf

Antimicrobial peptides: promising alternatives to conventional antibiotics.

Antimicrobial peptides have captured the attention of researchers in recent years because of their efficiency in fighting against pathogens. These peptides are found in nature and have been isolated from a wide range of organisms. Furthermore, analogs or synthetic derivatives have successfully been developed on the basis of natural peptide patterns. Long use of pesticides and antibiotics has led to development of resistance among pathogens and other pests as well as increase of environmental and health risks. Antimicrobial peptides are under consideration as new substitutes for conventional pesticides and antibiotics. Many plants and animals have been manipulated with antimicrobial peptide-encoding genes and several pesticides and drugs have been produced based on these peptides. Such strategies and products may still have a long way to go before being confirmed by regulatory bodies and others need to surmount technical problems before being accepted as applicable ones. In spite of these facts, several cases of successful use of antimicrobial peptides in agriculture and food industry indicate a promising future for extensive application of these peptides. In this review, we consider the developing field of antimicrobial peptide applications in various agricultural activities.

Application of antimicrobial peptides in agriculture and food industry

Antimicrobial peptides are a potent group of defense active molecules that have been utilized in developing resistance against a multitude of plant pathogens. Floral defensins constitute a group of cysteine-rich peptides showing potent growth inhibition of pathogenic filamentous fungi especially Fusarium oxysporum in vitro. Full length genes coding for two Petunia floral defensins, PhDef1 and PhDef2 having unique C- terminal 31 and 27 amino acid long predicted prodomains, were overexpressed in transgenic banana plants using embryogenic cells as explants for Agrobacterium–mediated genetic transformation. High level constitutive expression of these defensins in elite banana cv. Rasthali led to significant resistance against infection of Fusarium oxysporum f. sp. cubense as shown by in vitro and ex vivo bioassay studies. Transgenic banana lines expressing either of the two defensins were clearly less chlorotic and had significantly less infestation and discoloration in the vital corm region of the plant as compared to untransformed controls. Transgenic banana plants expressing high level of full-length PhDef1 and PhDef2 were phenotypically normal and no stunting was observed. In conclusion, our results suggest that high-level constitutive expression of floral defensins having distinctive prodomains is an efficient strategy for development of fungal resistance in economically important fruit crops like banana.

/pdf/petunia-floral-defensins-with-unique-prodomains-as-novel-aq7ibyuy38.pdf

Petunia floral defensins with unique prodomains as novel candidates for development of fusarium wilt resistance in transgenic banana plants.

Antibacterial, antifungal and toxicity of rare Iranian plants.

Metabolome Comparison of Transgenic and Non-transgenic Rice by Statistical Analysis of FTIR and NMR Spectra

Antimicrobial peptides are short peptides (< 100 amino acids) that have a potent function against microbial invasion. These peptides are produced by various organisms, including bacteria, fungi, flowering and non-flowering plants, insects and mammals. Antifungal peptides are a major group of antimicrobial peptides that have a specially potent effect against fungi. Several parameters affect the activity of antifungal peptides, including the sequence, size, charge, degree of structure formation, cationicity, hydrophobicity and amphipathicity. By analysis of numerous antifungal peptide sequences, the roles of these parameters in the structure of antifungal peptides are investigated in this review and by the in silico analysis of the existing residues, occupying each position of sequence, a template sequence is defined to generate potent and efficient lead antifungal peptides.

In silico analysis of antifungal peptides

Currents are unique drivers of oceanic phylogeography and so determine the distribution of marine coastal species, along with past glaciations and sea level changes. Here, we reconstruct the worldwide colonization history of eelgrass (Zostera marina L.), the most widely distributed marine flowering plant or seagrass from its origin in the Northwest Pacific, based on nuclear and chloroplast genomes. We identified two divergent Pacific clades with evidence for admixture along the East Pacific coast. Multiple west to east (trans-Pacific) colonization events support the key role of the North Pacific Current. Time-calibrated nuclear and chloroplast phylogenies yielded concordant estimates of the arrival of Z. marina in the Atlantic through the Canadian Arctic, suggesting that eelgrass-based ecosystems, hotspots of biodiversity and carbon sequestration, have only been present since ∼208 Kya (thousand years ago). Mediterranean populations were founded ∼53 Kya while extant distributions along western and eastern Atlantic shores coincide with the end of the Last Glacial Maximum (∼20 Kya). The recent colonization and 5-to 7-fold lower genomic diversity of Atlantic compared to the Pacific populations raises concern and opportunity about how Atlantic eelgrass might respond to rapidly warming coastal oceans.

Keykhosrow Keymanesh

Papers

Application of antimicrobial peptides in agriculture and food industry

Antibacterial, antifungal and toxicity of rare Iranian plants.

Metabolome Comparison of Transgenic and Non-transgenic Rice by Statistical Analysis of FTIR and NMR Spectra

In silico analysis of antifungal peptides

Ocean currents drive the worldwide colonization of the most widespread marine plant, eelgrass (Zostera marina)