Elm and alder yellows: etiology, symptomatology and epidemiology

Elm yellows (EY) and alder yellows (ALY) are decline diseases associated with the presence of phytoplasmas that affects several Ulmus (elm) and Alnus (alder) species, respectively. EY is widespread in North America and Europe whereas ALY is restricted to Europe. These diseases are mainly associated with the presence of closely related phytoplasmas, the EY agent ‘Candidatus Phytoplasma ulmi’ and the ALY agent, which are members of the EY or 16SrV group, subgroups 16SrV-A and -C, respectively. EY symptoms vary among the elm species. Foliar yellowing, extensive phloem necrosis and death are predominant in North American species. In contrast, European and Asian species are primarily characterized by witches’ brooms, do not show phloem necrosis and are less prone to severe decline. In all ALY-affected species the symptoms are similar and include yellowing, sparse foliage, premature autumn coloration, reduced terminal growth, dieback and decline. However, latent infections are also common in both plant species. The elm leafhopper Scaphoideus luteolus is the insect vector of EY phytoplasma in North America, whereas Macropsis mendax has been reported as vector in Northern Italy. The ALY phytoplasma is transmitted by Oncopsis alni. This leafhopper, which feeds occasionally on grapevine, can transmit ALY strains from alder to grapevine

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Not AvailableDuring a survey on arecanut palms in Sullia district of Karnataka, yellowing of leaves and shedding of both mature and immature fruits were observed in June 2013. The disease association with phytoplasmas was confirmed using nested polymerase chain reaction with phytoplasma specific ribosomal primers, which amplified the 1 6S rRNA gene in leaves, roots and rachis tissues of symptomatic arecanut palms. BLAST analysis of ∼1.2kb sequence of amplicon from symptomatic leaf samples revealed 99% sequence identity with 16S rDNA sequences of ‘Candidatus Phytoplasma asteris’ (16SrI). Phylogenetic analysis based on 16S rDNA also confirmed the clustering of areacanut yellow leaf disease phytoplasma with members of 16SrI group. Real and virtual RFLP analysis suggested that the arecanut phytoplasmas in the present study belongs to 16SrI-B subgroup. The identification of 16SrI-B subgroup phytoplasma in yellow leaf disease of arecanut is the first report from India.Not Availabl

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Not AvailableDuring 2019, spinach (Spinacia oleracea L.) belonging to the family Chenopodiaceae (var. All Green) expressing symptoms of flat stem, indicative of phytoplasma infection were observed at the seed production block of the Indian Institute of Vegetable Research (IIVR) farm (Uttar Pradesh, India). The disease incidence ranged from 10–20%. To confirm the phytoplasma presence, total DNA was extracted from the stem tissue of 7 symptomatic samples along with 4 asymptomatic samples. The amplification of ribosomal DNA was done by nested PCR assay with universal primer pairs P1/P7 followed by nested primer pair 3Fwd/3Rev (Manimekalai et al. 2010). Semi-nested PCR assay was performed to amplify secA gene using SecAfor1/SecArev3 and SecAfor2/SecArev3 primer pairs (Hodgetts et al. 2008). Amplicons of 1.3 kb corresponding to 16S rDNA region and 480 bp to secA region were yielded only from symptomatic samples. Amplicons were sequenced directly from 3 randomly selected samples. Sequences showed 100% identity among themselves and were submitted directly to NCBI database (GenBank Accession No. MW137921 and MW139906). Pairwise analysis of 16S rDNA and secA gene indicated maximum identity with two Polish aster yellows phytoplasma strains infecting sugar beet (KU720554, 100% sequence identity) in different parts of the globe and rapeseed phyllody phytoplasma (CP055264, 99.8% sequence identity), both belonging to the 16SrI-B phytoplasma sub-group (‘Candidatus Phytoplasma asteris’). Further in iPhyClassifier analysis, the virtual RFLP pattern using 17 restriction enzymes of 16S rDNA gene sequence …Not Availabl

2-Bromo-3-hydroxy-6-methylpyridine

In the title compound, C6H6BrNO, the Br atom is displaced from the pyridine ring mean plane by 0.0948 (3) Å, while the hydroxyl O atom and the methyl C atom are displaced by 0.0173 (19) and 0.015 (3) Å, respectively. In the crystal, molecules are linked via O—H...N hydrogen bonds, forming chains propagating along the a-axis direction. These chains are linked by C—H...Br hydrogen bonds, forming corrugated two-dimensional networks lying parallel to the ac plane

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Not AvailableFoot-and-mouth disease (FMD) endangers a large number of livestock populations across the globe being a highly contagious viral infection in wild and domestic cloven-hoofed animals. It adversely affects the socioeconomic status of millions of households. Vaccination has been used to protect animals against FMD virus (FMDV) to some extent but the effectiveness of available vaccines has been decreased due to high genetic variability in the FMDV genome. Another key aspect that the current vaccines are not favored is they do not provide the ability to differentiate between infected and vaccinated animals. Thus, RNA interference (RNAi) being a potential strategy to control virus replication, has opened up a new avenue for controlling the viral transmission. Hence, an attempt has been made here to establish the role of RNAi in therapeutic developments for FMD by computationally identifying (i) microRNA (miRNA) targets in FMDV using target prediction algorithms, (ii) targetable genomic regions in FMDV based on their dissimilarity with the host genome and, (iii) plausible anti-FMDV miRNA-like simulated nucleotide sequences (SNSs). The results revealed 12 mature host miRNAs that have 284 targets in 98 distinct FMDV genomic sequences. Wet-lab validation for anti-FMDV properties of 8 host miRNAs was carried out and all were observed to confer variable magnitude of antiviral effect. In addition, 14 miRBase miRNAs were found with better target accessibility in FMDV than that of Bos taurus. Further, 8 putative targetable regions having sense strand properties of siRNAs were identified on FMDV genes that are highly dissimilar with the host genome. A total of 16 SNSs having > 90% identity with mature miRNAs were also identified that have targets in FMDV genes. The information generated from this study is populated at http://bioinformatics.iasri.res.in/fmdisc/ to cater the needs of biologists, veterinarians and animal scientists working on FMD.Not Availabl

Updates on phytoplasma diseases associated with sugarcane in Asia.

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