Molecular diagnostic tools for the detection and characterization of Phoma tracheiphila

In the recent years PCR-based techniques for the identification and detection of Phoma tracheiphila, the causal agent of citrus mal secco disease, have been evaluated aiming to provide tools for biological and epidemiological studies. A wide collection of P. tracheiphila strains was used to evaluate and validate diagnostic protocols and a fAFLP method for fungal characterization. Conventional and real-time PCR protocols were successfully tested for the specific identification of P. tracheiphila and its detection in planta. A further improvement of the real-time PCR protocol and the DNA extraction methods allowed the quantification of the fungus both from naturally infected and artificially …

Collecting and preserving plant DNA for huanglongbing diagnosis in citrus samples from China

Accurate and sensitive detection of Citrus Huanglongbing associated ‘Ca. Liberibacter’species, not currently reported in the European and Mediterranean area, is an imperative need to define certification programs, to prevent introduction of the bacteria and/or their vectors in the unaffected areas, and to delineate efficient management strategies in those areas where the disease has spread. In this study, we compared different citrus sample preparation procedures for PCR based detection methods of ‘Candidatus Liberibacter asiaticus’, in order to find out the best a way to transport and preserve samples of Shatangju mandarin and fingered citron obtained during a survey in citrus orchards in …

Characterization of Alternaria alternata Isolates from Tangerine Hybrids Affected by Brown Spot in Italy

Alternaria brown spot, caused by Alternaria alternata, is the most important disease of tangerines and their hybrids worldwide, including Italy. The disease represents, for some susceptible citrus cultivar, a limiting factor in profitable cultivation. The results of the characterization of A. alternata isolates obtained from lesions on leaves and fruits of Fortune, Nova and Winola hybrids and Valencia sweet orange, collected in two groves located in Calabria and Sicily, is reported. An endopolygalacturonase gene (endoPG) was sequenced from five representative strains and a phylogenetic tree based on endoPG sequence data of Italian isolates and those of citrus associated Alternaria species d…

Poly(hydroxyalkanoate) synthase genes in pseudomonads strains, isolation and heterologous expression

Draft genome sequence of Pseudomonas corrugata, a phytopathogenic bacterium with potential industrial applications

Pseudomonas corrugata was first described as the causal agent of a tomato disease called 'pith necrosis' yet it is considered as a biological resource in various fields such as biocontrol of plant diseases and production of industrially promising microbial biopolymers (mcl-PHA). Here we report the first draft genome sequence of this species. © 2014 Elsevier B.V.

Occurrence of the T36 Genotype of Citrus tristeza virus in Citrus Orchards in Sicily, Italy

Recent phylogenetic studies have shown that different lineages representing mild and virulent Citrus tristeza virus (CTV) isolates have been present in Italy for a long time. The genetic structure of CTV population, based on p23 and p27 genes sequences, highlighted two main clusters referred to as T30 and VT-like, as confirmed by the full genomes sequences of two representative isolates SG29 (KC748392) and Bau282 (KC748391) (Licciardello et al. 2015). On the basis of risk analyses, regulatory measures have been outlined, including the recommendation to replace sour orange (C. aurantium) with tolerant rootstocks and to monitor the spread and the presence (if any) of different isolates not co…

Transcriptome analysis of Pseudomonas mediterranea and P. corrugata plant pathogens during accumulation of medium-chain-length PHAs by glycerol bioconversion

Pseudomonas corrugata and P. mediterranea are soil inhabitant bacteria, generally living as endophytes on symptomless plants and bare soil, but also capable of causing plant diseases. They share a similar genome size and a high proteome similarity. P. corrugata produces many biomolecules which play an important role in bacterial cell survival and fitness. Both species produce different medium-chain-length PHAs (mcl-PHAs) from the bioconversion of glycerol to a transparent film in P. mediterranea and a sticky elastomer in P. corrugata. In this work, using RNA-seq we investigated the transcriptional profiles of both bacteria at the early stationary growth phase with glycerol as the carbon sou…

Emergence and Phylodynamics of Citrus tristeza virus in Sicily, Italy

Citrus tristeza virus (CTV) outbreaks were detected in Sicily island, Italy for the first time in 2002. To gain insight into the evolutionary forces driving the emergence and phylogeography of these CTV populations, we determined and analyzed the nucleotide sequences of the p20 gene from 108 CTV isolates collected from 2002 to 2009. Bayesian phylogenetic analysis revealed that mild and severe CTV isolates belonging to five different clades (lineages) were introduced in Sicily in 2002. Phylogeographic analysis showed that four lineages co-circulated in the main citrus growing area located in Eastern Sicily. However, only one lineage (composed of mild isolates) spread to distant areas of Sici…