Bacterial endophytome sources, profile and dynamics—a conceptual framework

Currently, it seems inconceivable to dispute the major role of microorganisms in human health or insects with endosymbionts. Although microbial endophytes were discovered long ago, little is known about the roles of plant-associated microorganisms. Some endophytes are horizontally transmitted, whereas others are seed-borne; together, they influence plant health. Beneficial endophytes can promote plant growth and yield by increasing plant resistance to biotic and abiotic stresses. Recently, the tools available to study the phytobiome have much improved, opening doors for a better understanding of the fascinating interactions taking place at the plant level. This review redefines the conceptual framework for “endophyte” and “endophytome,” focusing on the intricate dynamics of bacterial endophytomes. Systematically examining the formation pathways and profiling endophytes allows for a comprehensive exploration of the intricate dynamics governing plant-microbe interactions. Additionally, the assessment of how endophytomes are influenced by both biotic and abiotic factors provides essential insights into the adaptability and resilience of plant-associated microorganisms. Our comprehensive analysis integrates genomic insights with environmental considerations, offering a nuanced perspective on the functional roles of bacterial endophytomes. Therefore, a new, inclusive definition is essential to accurately represent the complexity of interactions within the plant microbiome as well as having the whole picture of associated concepts

Nesidiocoris tenuis in Burkina Faso: Distribution, predatory capacity and insecticide sensibility

Tuta absoluta (Lepidoptera: Gelechiidae) is a worldwide invasive insect species, considered a major pest of tomato. It has recently established in Burkina Faso, where chemical control remains the only affordable option to limit damage. Nesidiocoris tenuis (Hemiptera: Miridae) is commercialised as a biological agent to control this pest in other parts of the world. But no literature is available on this predator in Burkina Faso. Therefore, in this study, we (1) scoured the country to determine its distribution and abundance in tomato fields, (2) verified its ability to consume T. absoluta eggs in two scenarios: the first one where N. tenuis has to search for the eggs on the plants and the second one in Petri dishes where the eggs are placed and N. tenuis could consume the eggs at will (3) measure the susceptibility of both insects to insecticides (two synthetic insecticides, three bio-bacterial insecticides and eight plant extracts) using the IRAC 022 method. It appears that, N. tenuis was found in 13 regions of the country with very interesting densities in some tomato fields (up to 80 individuals / m2). All stages of N. tenuis consume T. absoluta eggs and the number of eggs consumed depends on the stage of development and mode of egg delivery. When he has to look for some on the leaves, the adults find about 20 eggs to consume per day, while for an availability and consumption at will of eggs, he consumes about 45 eggs per day. Abamectin, emamectin benzoate, spinosad, spinetoram were very toxic for both T. absoluta and N. tenuis. In contrast, biopesticides including Bacillus thuringiensis, neem oil, Cleome viscosa, Ocimum basilicum and Cassia occidentalis were found to be compatible with N. tenuis while controlling T. absoluta. Based on our results, we recommend that through training for growers, they can be shown the importance of N. tenuis in the management of T. absoluta. We therefore recommend the use of biopesticides in combination with N. tenuis in the control of T. absoluta in Burkina Faso.Production Durable Intégrant la Recherche (ProDuIRe

Quantification de l\u27inoculum fongique aérien, une innovation dans le développement d\u27outils d\u27aide à la décision en blé

L\u27étude des profils d\u27inoculum aérien aide à mieux comprendre l\u27épidémiologie des maladies disséminées par le vent (origine et quantité d\u27inoculum), permet le développement de nouveaux outils d\u27aide à la décision (détection avant l\u27apparition des symptômes), peut s\u27appliquer à toutes les épidémies dans lesquelles intervient un inoculum aérien

Phytosanitary practices of tomato growers in Burkina Faso and risks for health and the environment.

Pour évaluer les pratiques phytosanitaires des maraîchers du Burkina Faso, des enquêtes ont été réalisées en 2015 et 2016 auprès de 316 producteurs dans les zones Ouest et Nord du pays. Seuls 9 % d’entre eux ont reçu une formation en protection des végétaux. Quatre-vingt-dix pour cent des pesticides utilisés sont achetés sur les marchés locaux sans garantie de conformité et de qualité. La lambdacyhalothrine de la famille des pyréthrinoïdes est la substance active la plus utilisée. L’utilisation sur tomate des pesticides formulés pour le coton a fortement progressé entre 2015 et 2016 (71 %). Les doses utilisées par les producteurs sont supérieures à celles recommandées. Plus de 70 % des maraîchers n’observent aucune mesure de protection adéquate depuis la préparation de la bouillie jusqu’à la fin des traitements. Le respect de délais sans traitement avant récolte dépend plus de l’état sanitaire des parcelles que des recommandations. Les contenants vides sont abandonnés sur les lieux de traitement par 53 % des répondants. Les pratiques phytosanitaires des maraîchers du Burkina Faso sont donc préoccupantes et potentiellement nuisibles pour la santé des agriculteurs et des consommateurs, et pour l’environnement.To assess the phytosanitary practices of tomato growers in Burkina Faso, surveys were carried out in 2015 and 2016 among 316 producers in the West and North zones of the country. Ninety percent of pesticides used by producers are purchased in local markets without guarantee of conformity or quality. Lambda-cyhalothrin of the pyrethroids family was the most used active substance. The use for tomato crop of cotton pesticides increased strongly between 2015 and 2016 (þ71%). The doses used by producers are higher than the recommended ones. More than 70% of the market gardeners do not observe any measure of adequate protection from the preparation of the mixture until the end of the treatments. The respect of preharvest interval depends mostly of the crop health status and does not follow the recommendations. Empty containers of pesticides are left in fields by 53% of the farmers. These results show that the phytosanitary practices of tomato producers are unsuitable and potentially harmful to the health of farmers and consumers and to the environment.Projet PIC « Projet de renforcement des capacités de diagnostic et de gestion intégrée des problèmes phytosanitaires au Burkina Faso

Vertical distributions of Fusarium spp. infections on mature wheat ears under natural field conditions

Wheat spikes have a vertical architecture, presenting multiple spikelets on which Fusarium spp. infectious propagules can land, initiate grain infection and possibly spread into the rachis to infect neighboring kernels. However, it is not known whether fungal infections occur randomly along the ear nor if species naturally interact within the ear. Over 4 years, five wheat fields in Belgium were surveyed annually and Fusarium spp. were isolated from kernels sampled from three positions on the ears (top, middle and bottom). This study revealed a vertical gradient of infection by Fusarium spp., with more isolates recovered from the bottom than from the top of the ears. This observation could result from infections by an inoculum from the ground, a downward movement of propagules present on the ear surface carried by rain and/or a downward spread of the fungus within the rachis. Moreover, multiple infected kernels originating from the same spike were frequent but, in most cases, the same species could be isolated from those grains and almost no relationships were observed among species present on the same spikes. Therefore, Fusarium spp. infections on wheat ears occur preferentially at the bottom of the spike and independently of the other species present

In Vitro Dual Culture of Polymyxa betae in Agrobacterium rhizogenes Transformed Sugar Beet Hairy Roots in Liquid Media

Polymyxa betae is a soil-borne protist and an obligate parasite of sugar beet that transmits the beet necrotic yellow vein virus. Sugar beet hairy roots, transformed by Agrobacterium rhizogenes, were inoculated with surface-sterilized root fragments infected by P. betae. After 10 wk in a liquid medium, typical structures of P. betae were observed in this in vitro system. This first in vitro culture of P. betae in liquid medium will contribute to a better understanding of this protist's biology through providing a way to conserve and produce purified isolates of the protist

Are endophytic bacteria involvedin increasing plant drought tolerance provided by humic and fulvic acids application ?

Positive effects of humic and fulvic acids (HA)-based biostimulants on plant tolerance to drought stress are reported in the literature. Little is known on the mechanisms of action of HA but the regulation of hormonal and redox metabolisms within plants is involved. Based on a plant study model under controlled conditions, the effect of HA in increasing drought stress resistance is assessed and the potential role of bacterial endophytic community in this processis analyzed. Positive impacts of HA on tomato plants grown in hydroponics under osmotic stress were observed on morphological and physiological parameters with an increase of fresh, dry and water weight of aerial and roots parts, plant length and leaf area, as well as a raise of stomatal conductance and total chlorophyll content. The reduction of the malondialdehyde concentration in aerial parts of plants treated with HA reflects a reduction of oxidative stress. The interaction between HA and endophytic bacteria associated to tomato seeds was studied in a second bioassay. Seeds are known to be a major vehicle for PGP bacteria through generations and to maintain a stable community in plants. For this purpose, a sterile culture system in hydroponics was developed. The positive effects of HA were confirmed and the culture in sterile conditions enabled to isolate seed endophytic bacteria, offering new opportunities in studying seed endophytic bacteria–HA interactions