Bacterial wilt resistance in tomato, eggplant and pepper : genetic resources challenged with the multifaceted Ralstonia solanacearum species complex : [P3-49]

Bacterial wilt caused by strains belonging to the #Ralstonia solanacearum# species complex inflicts severe economic losses in many crops worldwide. Host resistance remains the most effective control strategy against the bacterial wilt. However, interactions among plant, strain and environment often result in overcoming resistance properties due to variation in strain pathogenicity and adaptation. To help breeders circumvent this problem, we assembled a worldwide collection of 30 accessions of Tomato, Eggplant and Pepper (Core-TEP) that are commonly used as sources of resistance to #R. solanacearum# or for mapping QTLs. The Core-TEP lines were challenged with a core collection of 12 pathogen strains (Core-Rs2) representing the phylogenetic diversity of #R. solanacearum#. To our knowledge, this is the first study that investigated bacterial wilt resistance in a set of worldwide genetic resources used as sources of resistance in three solanaceous species (tomato, eggplant, and pepper). Our results showed that none of the Core-TEP accessions, representative of the TEP genetic diversity for resistance, was resistant to all Core-Rs2 strains. Hence, none of them displayed universal resistance. We observed six wilt interaction phenotypes, from highly susceptible to highly resistant. Intermediate phenotype resulted from the ability of plants to tolerate latent infections, i.e. bacterial colonization of vascular elements with limited or no wilting. #R. solanacearum# strains exhibited specific patterns of interaction with Core-TEP accessions. Thanks to several similarities of virulence patterns between strains of Core-Rs2, we defined two working concepts associated with two levels of resolution of the interactions between strains and plant phenotypes. One concept, the "pathoprofile" is based on the interactions for the three solanaceae taken together, and the other, the pathotype is based on the interactions for each plant species taken separately. The 12 Core-Rs2 strains partitioned into four pathotypes on Pepper accessions, five pathotypes on Tomato, six pathotypes on Eggplant, and six pathoprofiles on the whole set of Core-TEP accessions. Neither pathotypes nor pathoprofiles were phylotype-specific. Pathoprofiles with high pathogenicity were mainly found in strains from phylotypes I, IIB and III. One pathoprofile included a strain that overcame almost all resistance sources. (Résumé d'auteur

Are Tomato-Spotted Wilt Virus Management Tactics Good Enough?

Management of tomato-spotted wilt virus is complex and requires more than one treatment for near optimum results. We investigated tomato and pepper growers’ perception on the effectiveness of tactics using Bayesian Logistic regression. The perceived chance that each tactics will control the disease was about a coin toss.Tomato-spotted wilt virus, pest and disease management, Bayesian logistic regression, Agricultural and Food Policy, Crop Production/Industries, Farm Management, Food Security and Poverty, Production Economics, Research and Development/Tech Change/Emerging Technologies, Risk and Uncertainty,

Greenhouse screening for Fusarium wilt resistance in lupine

Fusarium wilt can cause total crop failure. Evaluation of Ffusarium resistance in heavily infected soil were performed in a grenhouse where the dominant fusarium species in the soil in descending order was F. oxysporum then F. avenaceum, F. culmorum, F. solani, F. gibbosum. Large fusarium wilt presure was observed and fully susceptible lines were completely destroyed by Fusarium wilt caused by F. oxisporum. Segregation in F2 and F3 in L. angustifolius showed that resistant genotypes have two dominant non-allelic resistance genes to wilt. We call this gene Relation to fusarium oxisporum (Rfo1,Rfo2). Susceptible genotypes have either two wild genes (++ ++) or one wild and one dominant resistant gene (++ Rfo2 Rfo2, or Rfo1Rfo1 ++). Crossing ‘++ Rfo2Rfo2’ to ‘Rfo1Rfo1 ++’ segregates in 9:7 resistant to susceptible in F2, respectively. The same segregation was observed by crossing ‘Rfo1Rfo1 Rfo2Rfo2’ to ‘++ ++’. We recommend the use of these resistant genes in breeding in areas with potential Fusarium wilt problems

Benign prostatic hyperplasia : Part 1- diagnosis

Peer reviewedPublisher PD

The Nozick Game

In this article I introduce a simple classroom exercise intended to help students better understand Robert Nozick’s famous Wilt Chamberlain thought experiment. I outline the setup and rules of the Basic Version of the Game and explain its primary pedagogical benefits. I then offer several more sophisticated versions of the Game which can help to illustrate the difference between Nozick’s libertarianism and luck egalitarianism

Evaluation of semiochemical based push-pull strategy for population suppression of ambrosia beetle vectors of laurel wilt disease in avocado.

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae and Platypodinae) bore into tree xylem to complete their life cycle, feeding on symbiotic fungi. Ambrosia beetles are a threat to avocado where they have been found to vector a symbiotic fungus, Raffaelea lauricola, the causal agent of the laurel wilt disease. We assessed the repellency of methyl salicylate and verbenone to two putative laurel wilt vectors in avocado, Xyleborus volvulus (Fabricius) and Xyleborus bispinatus (Eichhoff), under laboratory conditions. Then, we tested the same two chemicals released from SPLAT flowable matrix with and without low-dose ethanol dispensers for manipulation of ambrosia beetle populations occurring in commercial avocado. The potential active space of repellents was assessed by quantifying beetle catch on traps placed 'close' (~5-10 cm) and 'far' (~1-1.5 m) away from repellent dispensers. Ambrosia beetles collected on traps associated with all in-field treatments were identified to species to assess beetle diversity and community variation. Xyleborus volvulus was not repelled by methyl salicylate (MeSA) or verbenone in laboratory assays, while X. bispinatus was repelled by MeSA but not verbenone. Ambrosia beetle trap catches were reduced in the field more when plots were treated with verbenone dispensers (SPLAT) co-deployed with low-dose ethanol dispensers than when treated with verbenone alone. Beetle diversity was highest on traps deployed with low-dose ethanol lures. The repellent treatments and ethanol lures significantly altered the species composition of beetles captured in experiment plots. Our results indicate that verbenone co-deployed with ethanol lures holds potential for manipulating ambrosia beetle vectors via push-pull management in avocado. This tactic could discourage immigration and/or population establishment of ambrosia beetles in commercial avocado and function as an additional tool for management programs of laurel wilt

Le taux de wilt est-il un facteur limitant de la production des cacaoyers ?

La production des cacaoyers dépend de nombreux facteurs: le nombre de fleurs produites par arbre, la pollinisation des fleurs, la tenue des jeunes fruits, les dégâts occasionnés par les maladies et les ravageurs. Parmi ces facteurs, nous nous sommes intéressés à la tenue des jeunes fruits, et donc aux pertes dues au cherelle wilt. Le wilt affecte tous les cacaoyers en production et nous avons voulu répondre à la question : le taux de wilt est il un facteur de régulation de la production des arbres, c'est-à-dire, le taux de wilt augmente t'il avec la charge en fruits des arbres ? ou bien, ce taux est il indépendant de la production ? Pour répondre à ces questions, nous avons suivi le chérelle wilt durant 2 années consécutives sur une parcelle de cacaoyers hybrides : les chérelles wiltées, les cabosses malades et les cabosses mures saines ont été répertoriées chaque semaine et sur chaque arbre. Il apparaît que le wilt affecte l'ensemble des arbres même ceux ayant des niveaux de production très faibles et la moyenne du taux de wilt est supérieur à 50 %. Le taux de wilt est relativement constant en fonction de la charge en fruits des arbres jusqu'à une charge totale en fruits d'environ 100 cabosses adultes par arbre. Le wilt intervient donc comme facteur de régulation au delà d'une production par arbre dépassant les 100 cabosses adultes par arbre, soit une production d'environ 4 tonnes de cacao marchand à l'hectare, rendement très rarement atteint en parcelle de production. Le taux wilt est apparu très héritable dans un essai comparatif de clones au Cameroun et il est donc possible de réduire les pertes dues à ce problème par amélioration génétique. Il parait toutefois important d'étudier plus finement les processus physiologiques intervenant dans le wilt pour tenter de diminuer ce phénomène qui touche plus de 50% des jeunes fruits. (Résumé d'auteur

Hyperspectral Analysis of Pine Wilt Disease to Determine an Optimal Detection Index

Bursaphelenchus xylophilus, the pine wood nematode (PWN) which causes pine wilt disease, is currently a serious problem in East Asia, including in Japan, Korea, and China. This paper investigates the hyperspectral analysis of pine wilt disease to determine the optimal detection indices for measuring changes in the spectral reflectance characteristics and leaf reflectance in the Pinus thunbergii (black pine) forest on Geoje Island, South Korea. In the present study, we collected the leaf reflectance spectra of pine trees infected with pine wilt disease using a hyperspectrometer. We used 10 existing vegetation indices (based on hyperspectral data) and introduced the green-red spectral area index (GRSAI). We made comparisons between non-infected and infected trees over time. A t-test was then performed to find the most appropriate index for detecting pine wilt disease-infected pine trees. Our main result is that, in most of the infected trees, the reflectance changed in the red and mid-infrared wavelengths within two months after pine wilt infection. The vegetation atmospherically resistant index (VARI), vegetation index green (VIgreen), normalized wilt index (NWI), and GRSAI indices detected pine wilt disease infection faster than the other indices used. Importantly, the GRSAI results showed less variability than the results of the other indices. This optimal index for detecting pine wilt disease is generated by combining red and green wavelength bands. These results are expected to be useful in the early detection of pine wilt disease-infected trees