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https://doi.org/10.1016/j.semcdb.2018.02.004 © 2018 Elsevier Ltd Plant defensins are an extensive family of small cysteine rich proteins characterised by a conserved cysteine stabilised alpha beta protein fold which resembles the structure of insect and vertebrate defensins. However, secondary structure and disulphide topology indicates two independent superfamilies of defensins with similar structures that have arisen via an extreme case of convergent evolution. Defensins from plants and insects belong to the cis-defensin superfamily whereas mammalian defensins belong to the trans-defensin superfamily. Plant defensins are produced by all species of plants and although the structure is highly conserved, the amino acid sequences are highly variable with the exception of the cysteine residues that form the stabilising disulphide bonds and a few other conserved residues. The majority of plant defensins are components of the plant innate immune system but others have evolved additional functions ranging from roles in sexual reproduction and development to metal tolerance. This review focuses on the antifungal mechanisms of plant defensins. The activity of plant defensins is not limited to plant pathogens and many of the described mechanisms have been elucidated using yeast models. These mechanisms are more complex than simple membrane permeabilisation induced by many small antimicrobial peptides. Common themes that run through the characterised mechanisms are interactions with specific lipids, production of reactive oxygen species and induction of cell wall stress. Links between sequence motifs and functions are highlighted where appropriate. The complexity of the interactions between plant defensins and fungi helps explain why this protein superfamily is ubiquitous in plant innate immunity.

Copyright © 2019 Kerenga, McKenna, Harvey, Quimbar, Garcia-Ceron, Lay, Phan, Veneer, Vasa, Parisi, Shafee, van der Weerden, Hulett, Craik, Anderson and Bleackley. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Pathogenic microbes are developing resistance to established antibiotics, making the development of novel antimicrobial molecules paramount. One major resource for discovery of antimicrobials is the arsenal of innate immunity molecules that are part of the first line of pathogen defense in many organisms. Gene encoded cationic antimicrobial peptides are a major constituent of innate immune arsenals. Many of these peptides exhibit potent antimicrobial activity in vitro. However, a major hurdle that has impeded their development for use in the clinic is the loss of activity at physiological salt concentrations, attributed to weakening of the electrostatic interactions between the cationic peptide and anionic surfaces of the microbial cells in the presence of salt. Using plant defensins we have investigated the relationship between the charge of an antimicrobial peptide and its activity in media with elevated salt concentrations. Plant defensins are a large class of antifungal peptides that have remarkable stability at extremes of pH and temperature as well as resistance to protease digestion. A search of a database of over 1200 plant defensins identified ZmD32, a defensin from Zea mays, with a predicted charge of +10.1 at pH 7, the highest of any defensin in the database. Recombinant ZmD32 retained activity against a range of fungal species in media containing elevated concentrations of salt. In addition, ZmD32 was active against Candida albicans biofilms as well as both Gram negative and Gram-positive bacteria. This broad spectrum antimicrobial activity, combined with a low toxicity on human cells make ZmD32 an attractive lead for development of future antimicrobial molecules.

Tablas Este trabajo fue realizado en el municipio de Sáchica, Boyacá; donde se probaron nueve (9) híbridos nuevos de tomate contra el testigo comercial (Ichiban), las condiciones de germinación fueron en laboratorio en condiciones controladas y el cultivo fue en condiciones de invernadero, la ubicación de los experimentos se realizó mediante un diseño completamente a azar con veinte (20) individuos por cada tratamiento, todos los tratamientos tuvieron el mismo manejo agronómico. Los parámetros medidos en este estudio fueron: porcentaje de germinación, tolerancia a plagas y enfermedades, desarrollo florar y rendimiento, calidad de la producción, comportamiento post-cosecha y por último se realizó un análisis económico de cada uno de los tratamientos evaluados con respecto al testigo comercial. Los resultados fueron analizados con el programa estadístico SAS. En el análisis económico y agronómico ninguno de los tratamientos probados fue superior al testigo, a pesar de que el tratamiento T9 (PAZ 811) se acercó a los rendimientos del tratamiento testigo pero en el análisis económico siguió siendo superior el testigo, por eso la principal recomendación fue continuar análisis enfocados en este tratamiento variando nutrición y manejo para mejorar su rendimiento agronómico. This work was realized in Sáchica, Boyacá; where nine (9) new tomato hybrids were tested against the commercial control (Ichiban), germination conditions were in the laboratory under controlled conditions and the crop was under greenhouse conditions, the location of the experiments were performed using a design completely random with twenty (20) plants per treatment, all treatments had the same agronomic management. The parameters measured in this study were: percentage of germination, tolerance to pests and diseases, leaf development and performance, quality of production, postharvest behavior and finally an economic analysis of each of the treatments evaluated against to commercial control. The results were analyzed using the SAS statistical program. In the economic and agronomic analysis none of the tested treatments was superior to the control, even though the treatment T9 (PAZ 811) yields approached the control treatment but in economic analysis remained above the control, so the main recommendation was to continue focusing analysis in this treatment varying nutrition and management to improve their agronomic performance.

El trabajo fue presentado en la sección monográfica sobre lenguaje tabú en el mencionado congreso. This contribution will deal with two topics closely related and intermingled. I firstly will try to show how one of the salient features of euphemisms is their ambiguity and/or vagueness (Grondelaers and Geeraerts, 1998) to the extent that even sentences in which lexicalised euphemisms are used can become dysphemistic if they are not ambiguous. This means that ambiguous and/or vague sentences play a fundamental, cognitive role (Tuggy, 2006). This is the case of a well-known excerpt from Somerset Maugham in which, in spite of the fact that all the nouns used are euphemisms, the excerpt itself can be considered dysphemistic. Conversely, I will show two instances from two songs in which female pudenda are euphemistically and ambiguously alluded to. Secondly, I will try to apply my previous reflections to politically correct language. In order to do so I will take as a starting point the fact that political correctness spread across the western countries in the same decade (1960-1970) in which the motto “Il est interdit d’interdire” got also trendy (Hughes, 2006 and 2010). As a result of the fact that the noun ‘prohibition’ (and its cognates, derivatives and synonyms) became “prohibited” as a politically incorrect word, prohibition itself has to be phrased in ambiguous sentences. For instance, instead of the (currently) politically incorrect notice “No Smoking” or “Smoking is prohibited”, we frequently find the politically correct one “Thank you for not smoking”, where the sentence meaning is pretty different from what the author of the notice tries to mean; since the sentence meaning is that someone thanks you for not smoking, while what the author of the notice intends to mean that smoking is prohibited. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.