Nota corta. Efecto del biotipo de Bemisia tabaci en la transmisión del virus del rizado amarillo del tomate (TYLCSV-ES) entre tomate y malas hierbas

The common five weed species Datura stramonium L., Solanum nigrum L., Brassica kaber (DC), Capsella bursapastoris L. and Malva parviflora L., were tested for their susceptibility to an isolate of TYLCSV from Murcia, Spain (TYLCSV-ES), using the B-, Q- and S-biotypes of Bemisia tabaci (Gennadius). Both, B- and Q-biotypes were shown to transmit TYLCSV-ES from infected tomato to S. nigrum and D. stramonium and vice versa. Transmission efficiency from tomato to these weeds varied from 58.3% to 83.3%. Transmission efficiency from the infected weeds back to tomato varied from 66.7% to 100%. No significant difference between the B- and Q-biotypes was found in transmission efficiency from infected tomato to weed plants and from D. stramonium back to tomato. However, a significant difference in transmission efficiency from infected S. nigrum plants to tomato was detected between the B- and Qbiotypes. No other tested weed species were found to be infected by or host TYLCSV-ES. The S-biotype was unable to survive on tomato long enough to acquire or transmit TYLCSV-ES and could only transmit the virus from S. nigrum to S. nigrum at a very low efficiency. The implications of these results for the epidemiology of TYLCV´s in the field are discussed.Se analizó la susceptibilidad de las malas hierbas Datura stramonium L., Solanum nigrum L., Brassica kaber (DC), Capsella bursa-pastoris L. and Malva parviflora L. a un aislado del TYLCSV procedente de Murcia, España (TYLCSVES), utilizando como vectores los biotipos B, Q y S de Bemisia tabaci (Gennadius). Los biotipos B y Q transmitieron el TYLCSV-ES desde tomate infectado a S. nigrum y D. stramonium y viceversa, con una eficiencia de transmisión desde tomate a dichas malas hierbas entre el 58,3% y el 83,3%. La eficiencia de transmisión desde las malas hierbas al tomate varió desde el 66,7% al 100%. No se apreciaron diferencias significativas entre los biotipos B y Q respecto a la eficiencia de transmisión desde tomate a malas hierbas ni desde D. stramonium a tomate. No obstante, la eficiencia de transmisión desde plantas infectadas de S. nigrum a tomate fue significativamente diferente entre los biotipos B y Q. El aislado TYLCSV-ES no fue capaz de infectar a ninguna de las otras especies de malas hierbas utilizadas en este estudio. El biotipo S no pudo sobrevivir en tomate el tiempo suficiente para adquirir o transmitir el TYLCSVES, pudiendo solamente transmitir el virus desde S. nigrum a S. nigrum con una eficiencia muy limitada. Se discuten las implicaciones de estos resultados para la epidemiología en campo de los virus TYLCV

Establishment of an in vitro sciarid fly larvae assay to study plant resistance

UMR BGPI Equipe 1 - Equipe 6International audienceMechanisms underlying natural plant resistance to herbivorous invertebrates are still poorly understood in comparison with bacterial or fungal interactions. One reason is the difficulty in reliably and reproducibly assessing the effects under controlled conditions. This article describes a newly developed in vitro biological assay system that enables the interactions between sciarid larvae and plants, whose roots they feed on, to be studied under highly controlled conditions. The bioassay eliminates the problems created by the often variable environmental factors by providing an aseptic arena where experimental plants can be germinated and grown on agar within a Petri dish. Sciarid fly eggs are then collected, sterilised and added to the Petri dish. The system allows the eggs to hatch and the larvae to feed on the plant roots. A range of developmental parameters can then be recorded over time which can then be correlated with the experimental plant type. This assay system also allows a simultaneous comparison or 'choice chamber' between two (or more) different genotypes. The assay should greatly help to facilitate the identification of new components involved in insect resistance mediated pathway via the characterisation of mutant plant

Genome organization of ageratum yellow vein virus, a monopartite whitefly-transmitted geminivirus isolated from a common weed

Journal of General Virology76122915-2922JGVI

Identification of DNA Components Required for Induction of Cotton Leaf Curl Disease

AbstractCotton leaf curl disease (CLCuD) is a major constraint to cotton production in Pakistan. Infectious clones of the monopartite begomovirus cotton leaf curl virus (CLCuV), associated with diseased cotton, are unable to induce typical symptoms in host plants. We have identified and isolated a single-stranded DNA molecule approximately 1350 nucleotides in length which, when coinoculated with the begomovirus to cotton, induces symptoms typical of CLCuD, including vein swelling, vein darkening, leaf curling, and enations. This molecule (termed DNA β) requires the begomovirus for replication and encapsidation. The CLCuV/DNA 1/DNA β complex, together with a similar complex previously identified in Ageratum conyzoides, represent members of an entirely new type of infectious, disease-causing agents. The implications of this finding to our understanding of the evolution of new disease-causing agents are discussed