Evaluation of host resistance inducers and conventional products for fire blight management in loquat and quince

Fire blight disease is one of the most destructive diseases of pome fruits. Due to the lack of effective, non-phytotoxic and publicly acceptable materials for controlling fire blight in pome fruit trees, new strategies to manage Erwinia amylovora fire blight are being sought. The resistance-inducing compounds prohexadione-Ca, harpin protein and benzothiadiazole (acibenzolar-S-methyl), the fertilizer humic acid, the bactericides streptomycin and copper salts, and combinations of copper with chemicals were evaluated for their ability to control fire blight on quince and loquat cultivars. Prohexadione-Ca was applied at a rate of 125 mg L-1 at two shoot lengths (6-12 cm and 15-20 cm), while benzothiadiazole + metalaxyl (135 mg L-1) and harpin (50 mg L-1) were applied when the shoots measured between 15-20 cm, and again at 30-35 cm. On loquat cv. Cukurgobek, benzothiadiazole + metalaxyl showed about 60% effectiveness. The addition of copper salts reduced the effectiveness of benzothiadiazole + metalaxyl. On quince cultivars, streptomycin (P ≤ 0.05) was the most effective treatment during both years, followed by the harpin protein alone and in combination with copper salts. Prohexadione-Ca, benzothiadiazole + metalaxyl, and harpin protein applications reduced disease severity on inoculated shoots compared with copper and untreated controls. Prohexadione-Ca reduced both shoot length and shoot blight on the two hosts. Humic acid applications were ineffective in controlling fire blight on loquat and quince cultivars. Quince cv. Eşme showed lower disease severity than cv. Ekmek (P ≤ 0.05). The use of resistance-inducing substances during the early phase of shoot growth may offer a means of managing the shoot blight phase of fire blight disease on quince and loquat.La brûlure bactérienne est l'une des maladies les plus néfastes chez les fruits à pépins. En l'absence de produits efficaces, non phytotoxiques et socialement acceptables pour lutter contre cette maladie causée par Erwinia amylovora chez les pomoïdées, de nouvelles stratégies sont recherchées. La capacité de certains composés pouvant induire de la résistance (prohéxadione-Ca, protéine harpine et benzothiadiazole (acibenzolar-S-méthyle)), de l'acide humique utilisé en tant que fertilisant, de bactéricides (streptomycine et sel de cuivre), ainsi que des combinaisons de cuivre et de produits chimiques à lutter contre la brûlure bactérienne chez des cultivars de néflier du Japon et de cognassier a été évaluée. La prohéxadione-Ca a été appliquée à un taux de 125 mg L-1 sur deux longueurs de pousses (6-12 cm et 15-20 cm), tandis que le benzothiadiazole + métalaxyl (135 mg L-1) et l'harpine (50 mg L-1) ont été appliqués sur des pousses alors qu'elles mesuraient entre 15 et 20 cm, puis à nouveau alors qu'elles mesuraient entre 30 et 35 cm. Chez le néflier du Japon cv. Cukurgobek, un taux d'efficacité d'environ 60 % a été obtenu avec le benzothia- diazole + métalaxyl; cependant, l'ajout de sel de cuivre en a réduit l'efficacité. Sur les cultivars de cognassier, la protéine harpine, utilisée seule et en combinaison avec le sel de cuivre, s'est avérée le traitement le plus efficace durant les deux années de l'étude, après la streptomycine (P ≤ 0.05). La prohéxadione-Ca, le benzothiadiazole + métalaxyl et les protéines harpines ont réussi à réduire la gravité de la maladie chez des pousses inoculées comparativement aux témoins traités au cuivre et aux témoins non traités. La prohéxadione-Ca a réduit à la fois la longueur et la brûlure des pousses chez les deux hôtes. Les applications d'acide humique n'ont pas réussi à réduire l'incidence de la brûlure bactérienne chez les cultivars de néflier du Japon et de cognassier. Le cognassier cv. Eşme a été moins gravement affecté par la maladie que le cv. Ekmek (P ≤ 0.05). L'utilisation de substances pouvant induire de la résistance durant la phase initiale de croissance des pousses peut être une façon de lutter contre la brûlure des pousses causée par la brûlure bactérienne chez le cognassier et le néflier du Japon

A Genome-Wide Functional Investigation into the Roles of Receptor-Like Proteins in Arabidopsis

Receptor-like proteins (RLPs) are cell surface receptors that typically consist of an extracellular leucine-rich repeat domain, a transmembrane domain, and a short cytoplasmatic tail. In several plant species, RLPs have been found to play a role in disease resistance, such as the tomato (Solanum lycopersicum) Cf and Ve proteins and the apple (Malus domestica) HcrVf2 protein that mediate resistance against the fungal pathogens Cladosporium fulvum, Verticillium spp., and Venturia inaequalis, respectively. In addition, RLPs play a role in plant development; Arabidopsis (Arabidopsis thaliana) TOO MANY MOUTHS (TMM) regulates stomatal distribution, while Arabidopsis CLAVATA2 (CLV2) and its functional maize (Zea mays) ortholog FASCINATED EAR2 regulate meristem maintenance. In total, 57 RLP genes have been identified in the Arabidopsis genome and a genome-wide collection of T-DNA insertion lines was assembled. This collection was functionally analyzed with respect to plant growth and development and sensitivity to various stress responses, including susceptibility toward pathogens. A number of novel developmental phenotypes were revealed for our CLV2 and TMM insertion mutants. In addition, one AtRLP gene was found to mediate abscisic acid sensitivity and another AtRLP gene was found to influence nonhost resistance toward Pseudomonas syringae pv phaseolicola. This genome-wide collection of Arabidopsis RLP gene T-DNA insertion mutants provides a tool for future investigations into the biological roles of RLPs

Exploring the interaction between small RNAs and R genes during Brachypodium response to Fusarium culmorum infection

The present study aims to investigate small RNA interactions with putative disease response genes in the model grass species Brachypodium distachyon. The fungal pathogen Fusarium culmorum (Fusarium herein) and phytohormone salicylic acid treatment were used to induce the disease response in Brachypodium. Initially, 121 different putative disease response genes were identified using bioinformatic and homology based approaches. Computational prediction was used to identify 33 candidate new miRNA coding sequences, of which 9 were verified by analysis of small RNA sequence libraries. Putative Brachypodium miRNA target sites were identified in the disease response genes, and a subset of which were screened for expression and possible miRNA interactions in 5 different Brachypodium lines infected,with Fusarium. An NBS-LRR family gene, 1g34430, was polymorphic among the lines, forming two major genotypes, one of which has its miRNA target sites deleted, resulting in altered gene expression during infection. There were siRNAs putatively involved in regulation of this gene, indicating a role of small RNAs in the B. distachyon disease response

Genetic diversity and population structure of apple germplasm from Eastern Black Sea region of Turkey by SSRs

WOS:000736958200004Turkey has a diverse apple germplasm and Northeastern Anatolia had great contributions to domestication of the Malus genus. Despite quite high rainfall (900–2300 mm) and humidity (70–85%) levels, several local apple cultivars have been successfully grown for centuries at the coastal zone of Eastern Black Sea region of Northeastern Anatolia without any pesticide applications. In this study, a set of 206 local genotypes, including 6 international cultivars as references was analyzed using 13 SSR primers with the aim of assessing the genetic diversity and population structure among the genotypes. Bayesian genetic structure analysis was used to reveal differentiation of the groups and the results were confirmed by factorial correspondence analysis (FCA). A total of 234 alleles (average 18) were generated by 13 SSR markers. CH02c06 was the most informative (PI: 0.017) and CH03g07 was the least informative (PI: 0.07) locus. The average He was 0.859 with a range of 0.775–0.929 and the average Ho was 0.760 with a range of 0.556–0.872. Considerable genetic variation was detected among the genotypes and genetic similarity varied between 11 and 96%. A Bayesian genetic structure analysis indicated three subpopulations (K) and admixture among the accessions. Several loci yielded three alleles in 39 accessions. No synonyms or identical cultivars were detected but several genotypes known by the same names formed 22 homonym groups. The present SSR data will have great contributions to future germplasm management efforts as well as to further comparative studies that investigate genetic relationships among the local apples of Northeastern Anatolia

A genome-wide functional investigation into the roles of receptor-like proteins in Arabidopsis

Receptor-like proteins (RLPs) are cell surface receptors that typically consist of an extracellular leucine-rich repeat domain, a transmembrane domain, and a short cytoplasmatic tail. In several plant species, RLPs have been found to play a role in disease resistance, such as the tomato (Solanum lycopersicum) Cf and Ve proteins and the apple (Malus domestica) HcrVf2 protein that mediate resistance against the fungal pathogens Cladosporium fulvum, Verticillium spp., and Venturia inaequalis, respectively. In addition, RLPs play a role in plant development; Arabidopsis (Arabidopsis thaliana) TOO MANY MOUTHS (TMM) regulates stomatal distribution, while Arabidopsis CLAVATA2 (CLV2) and its functional maize (Zea mays) ortholog FASCINATED EAR2 regulate meristem maintenance. In total, 57 RLP genes have been identified in the Arabidopsis genome and a genome-wide collection of T-DNA insertion lines was assembled. This collection was functionally analyzed with respect to plant growth and development and sensitivity to various stress responses, including susceptibility toward pathogens. A number of novel developmental phenotypes were revealed for our CLV2 and TMM insertion mutants. In addition, one AtRLP gene was found to mediate abscisic acid sensitivity and another AtRLP gene was found to influence nonhost resistance toward Pseudomonas syringae pv phaseolicola. This genome-wide collection of Arabidopsis RLP gene T-DNA insertion mutants provides a tool for future investigations into the biological roles of RLPs