The unseen effect of pesticides: The impact on phytobiota structure and functions

In the last years, the diffusion and implementation of next-generation sequencing and the reduction of costs raised the interest in phytyobiome studies allowing to dissect the ecological interactions regulating the holobiont. Indeed, crop plants are associated with a wide diversity of microorganisms in all their parts. Crop microbiota influences plant phenotype, growth, yield and quality by contributing to plant resistance toward diseases, plant adaptation to abiotic stresses, and plant nutrition. The association between terrestrial plants and microbes developed at least 460 million years ago, as suggested by the fossil evidence of the earliest land plants, indicating the essential role of microbes for plants. Recent studies indicate that plants actively recruit beneficial microorganisms to facilitate their adaptation to environmental conditions. Cultivation methods and disease control measures can influence plant microbiome structure and functions. Both pesticide and biological control agent applications may alter the biodiversity inside the phytobiota and suppress beneficial functions. Nonetheless, to date, the effects of disease control measures on phytobiota and their possible side consequences on plant growth, crop productivity and quality remain a neglected field of study. The present work summarizes the known effects on phytobiota providing evidence about the role of plant microbial community in determining the overall efficacy of the applied control measure and suggests that future studies on plant disease control consider also the microbe-mediated effects on plant fitness

Early signaling events induced by elicitors of plant defenses.

Plant pathogen attacks are perceived through pathogen-issued compounds or plant-derived molecules that elicit defense reactions. Despite the large variety of elicitors, general schemes for cellular elicitor signaling leading to plant resistance can be drawn. In this article, we review early signaling events that happen after elicitor perception, including reversible protein phosphorylations, changes in the activities of plasma membrane proteins, variations in free calcium concentrations in cytosol and nucleus, and production of nitric oxide and active oxygen species. These events occur within the first minutes to a few hours after elicitor perception. One specific elicitor transduction pathway can use a combination or a partial combination of such events which can differ in kinetics and intensity depending on the stimulus. The links between the signaling events allow amplification of the signal transduction and ensure specificity to get appropriate plant defense reactions. This review first describes the early events induced by cryptogein, an elicitor of tobacco defense reactions, in order to give a general scheme for signal transduction that will be use as a thread to review signaling events monitored in different elicitor or plant models

Nitric oxide triggers a transient metabolic reprogramming in Arabidopsis

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Peroxynitrite formation and function in plants

Peroxynitrite (ONOO-) is a reactive nitrogen species formed when nitric oxide (NO) reacts with the superoxide anion (O-2(-)). It was first identified as a mediator of cell death in animals but was later shown to act as a positive regulator of cell signaling, mainly through the posttranslational modification of proteins by tyrosine nitration. In plants, peroxynitrite is not involved in NO-mediated cell death and its physiological function is poorly understood. However, it is emerging as a potential signaling molecule during the induction of defense responses against pathogens and this could be mediated by the selective nitration of tyrosine residues in a small number of proteins. In this review we discuss the general role of tyrosine nitration in plants and evaluate recent evidence suggesting that peroxynitrite is an effector of NO-mediated signaling following pathogen infection. (C) 2011 Elsevier Ireland Ltd. All rights reserved

Nitric oxide signalling in plants.

Small, simple and highly toxic, nitric oxide (NO) is a gas with a broad chemistry that involves an array of interrelated redox forms with different chemical reactivities. Named \u2018Molecule of the Year\u2019 in 1992, NO is now considered a \u2018do it all\u2019 molecule that plays a crucial role during the entire lifespan of the plant

A novel approach to study cGMP signalling in plants.

Description of an innovative genetic approach to study the role of cGMP as second messenger during plant defense responses

Nitric oxide signalling in plants.

Small, simple and highly toxic, nitric oxide (NO) is a gas with a broad chemistry that involves an array of interrelated redox forms with different chemical reactivities. Named \u2018Molecule of the Year\u2019 in 1992, NO is now considered a \u2018do it all\u2019 molecule that plays a crucial role during the entire lifespan of the plant

Peroxynitrite produced during the hypersensitive response could question the functional redundancy of AtMKK4 and AtMKK5 via selective nitration.

Peroxynitrite, formed from the reaction between nitric oxide and superoxide, and produced in plants during the hypersensitive response is able to nitrate specifically AtMKK4, whereas AtMKK4 closest homolog AtMKK5 is insensitive to peroxyntirite treatment. This suggests that both proteins can achieve unique functions in presence of nitrating agents, in particular in response to pathogen attacks

The specificity of tyrosine nitration questions the redundancy of AtMKK4 and AtMKK5 during plant defense responses.

Description of the inhibition of MAPK cascade of Arabidopsis thaliana via specific tyrosine nitration mediated by peroxynitrit