Characterisation of the genetic diversity of citrus viroid VII using amplicon sequencing.

Viroids occur in plants as swarms of sequence variants clustered around a dominant variant, leading to adoption of the term 'quasispecies' to describe the viroid population in an individual host. The composition of the quasispecies can potentially change according to the age of the infection, the position of the leaf or branch in the canopy, and the host species. The primary aim of this study was to investigate the quasispecies concept for citrus viroid VII (CVd-VII), a recently discovered member of the family Pospiviroidae.

Detection of Viroids by RT-PCR.

Reverse transcription-polymerase chain reaction (RT-PCR) is an effective method for detecting the presence of viroids in plant tissue. Viroid RNA is converted to cDNA and amplified to detectable levels, making it a fast and useful detection tool, even when the viroid is present at low levels. Methods of viroid detection using conventional RT-PCR are described in this chapter.

Development of a one-step RT-qPCR detection assay for the newly described citrus viroid VII.

An apscaviroid, tentatively named citrus viroid VII (CVd-VII), was recently discovered in citrus in Australia. A diagnostic assay using real-time reverse transcription polymerase chain reaction was developed and validated to detect the viroid in citrus plants. The assay showed a high level of sensitivity, reliably detecting 2000 plasmid copies per reaction, while down to 20 plasmid copies per reaction were occasionally detected.

Draft Genome Sequence of a Novel " Liberibacter" Species Detected in a Species from Bhutan.

The draft genome sequence of a novel " Liberibacter" species detected in an unidentified species of (Rutaceae) collected in Bhutan is reported. The total length is 1,408,989 bp with 1,169 coding sequences in 96 contigs, a GC content of 37.3%, and 76 to 77% average nucleotide identity with several other " Liberibacter" species.

Characterization of the bacterial communities of psyllids associated with Rutaceae in Bhutan by high throughput sequencing.

Background: Several plant-pathogenic bacteria are transmitted by insect vector species that often also act as hosts. In this interface, these bacteria encounter plant endophytic, insect endosymbiotic and other microbes. Here, we used high throughput sequencing to examine the bacterial communities of five different psyllids associated with citrus and related plants of Rutaceae in Bhutan: Diaphorina citri, Diaphorina communis, Cornopsylla rotundiconis, Cacopsylla heterogena and an unidentified Cacopsylla sp.

Genome Analysis of Melon Necrotic Spot Virus Incursions and Seed Interceptions in Australia.

Melon necrotic spot virus (MNSV) was detected in field-grown (rockmelon) and (watermelon) plants in the Sunraysia district of New South Wales and Victoria, Australia, in 2012, 2013, and 2016, and in two watermelon seed lots tested at the Australian border in 2016. High-throughput sequencing was used to generate near full-length genomes of six isolates detected during the incursions and seed testing. Phylogenetic analysis of the genomes suggests that there have been at least two incursions of MNSV into Australia and none of the field isolates were the same as the isolates detected in seeds.