Defense responses of Hevea brasiliensis to elicitors from root rot fungi

L'élicitation de quelques réactions de défense du système racinaire de l'Hévéa (#Hevea brasiliensis) aux attaques du #Rigidoporus lignosus$ a été réalisée en injectant des extraits des parois fongiques dans les racines de jeunes plantes âgées de 1 mois. Une étude de la cinétique a révélé, au microscope optique, une induction de la lignification 3, 8, 15 et 45 jours après l'injection d'éliciteurs. Les résultats obtenus montrent que certaines réactions de défense des racines des plantes ligneuses peuvent être stimulées par des éliciteurs fongiques dans le but de renforcer les barrières structurales des tissus hôtes. (D'après résumé d'auteur

The aggression of Hevea brasiliensis by Rigidoporus lignosus and Bhellinus noxius : some biochemical events

Abstract The activity and spatial distribution of eight enzymes in adult tap root tissues colonized by R. lignosus and P. noxius are investigated. Their physiological significance in the pathogenic process is discussed

Estimating the delay between host infection and disease (incubation period) and assessing its significance to the epidemiology of plant diseases.

Knowledge of the incubation period of infectious diseases (time between host infection and expression of disease symptoms) is crucial to our epidemiological understanding and the design of appropriate prevention and control policies. Plant diseases cause substantial damage to agricultural and arboricultural systems, but there is still very little information about how the incubation period varies within host populations. In this paper, we focus on the incubation period of soilborne plant pathogens, which are difficult to detect as they spread and infect the hosts underground and above-ground symptoms occur considerably later. We conducted experiments on Rhizoctonia solani in sugar beet, as an example patho-system, and used modelling approaches to estimate the incubation period distribution and demonstrate the impact of differing estimations on our epidemiological understanding of plant diseases. We present measurements of the incubation period obtained in field conditions, fit alternative probability models to the data, and show that the incubation period distribution changes with host age. By simulating spatially-explicit epidemiological models with different incubation-period distributions, we study the conditions for a significant time lag between epidemics of cryptic infection and the associated epidemics of symptomatic disease. We examine the sensitivity of this lag to differing distributional assumptions about the incubation period (i.e. exponential versus Gamma). We demonstrate that accurate information about the incubation period distribution of a pathosystem can be critical in assessing the true scale of pathogen invasion behind early disease symptoms in the field; likewise, it can be central to model-based prediction of epidemic risk and evaluation of disease management strategies. Our results highlight that reliance on observation of disease symptoms can cause significant delay in detection of soil-borne pathogen epidemics and mislead practitioners and epidemiologists about the timing, extent, and viability of disease control measures for limiting economic loss.ML thanks the Institut Technique français de la Betterave industrielle (ITB) for funding this project. CAG and JANF were funded by the UK’s Biotechnology and Biological Sciences Research Council (BBSRC). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Mathematical analysis and modeling of epidermics of Rubber Tree root diseases : Probability of infection of an individual tree

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