1,721,176 research outputs found
'Candidatus Phytoplasma phoenicium' associated with devastating diseases of stone fruits
Full text link‘Candidatus Phytoplasma phoenicium’, taxonomic subgroup 16SrIX-B, was found in association with a lethal devastating almond disease (almond witches’-broom, AlmWB) in Lebanon in the early 1990s. It was later reported in Iran starting in 1995. During the last two decades, the outbreak of AlmWB has led to a rapid decline of almond trees in northern regions and in the Bekaa Valley in Lebanon and in Fars province and in other southern provinces in Iran. In 2009, ‘Ca. P. phoenicium’ was also identified in association with a severe disease of peach and nectarine in southern Lebanon. From 2012 to 2017, 'Ca. P. phoenicium' was found associated with apricot yellows and peach witches'-broom in Iran. The most characteristic symptoms in almond trees are shoot proliferation on the main trunk with the appearance of a witches’ broom, perpendicular development of many axillary buds with small and yellowish leaves, and general tree decline with final dieback. The presence of witches’-broom is more common in almond trees than in peach/nectarine, while phyllody was observed only in peach. A total loss of production happens 1–2 years after the initial appearance of the symptoms. In Lebanon, AlmWB epidemiological cycle involves Asymmetrasca decedens (prevalent in almond), possibly responsible for the transmission of ‘Ca. P. phoenicium’ from almond to almond, and cixiids of the genus Tachycixius (prevalent in Smilax aspera L. and Anthemis sp.), possibly responsible for the transmission from weeds to almond. In Iran, Prunus scoparia, a wild almond species harboring 'Ca. P. phoenicium', could play a role in the phytoplasma transmission pathways to fruit trees. Based on detection of 'Ca. P. phoenicium' in insect body and saliva and the presence of consistent populations, the leafhopper Frutioidea bisignata can be considered as potential vector of this phytoplasma in Iran. Alignment of 16S rDNA nucleotide sequences of 'Ca. P. phoenicium' strains from Lebanon and Iran allowed the identification of 21 SNPs mutually exclusive in the phytoplasma strain populations identified in the two countries. The combination of such SNPs allowed the recognition of nine SNP lineages in Lebanon and eight in Iran. Multiple gene typing analyses of ‘Ca. P. phoenicium’ strains infecting almond, peach, and nectarine in Lebanon allowed the identification of distinct AlmWB-associated phytoplasma strains from diverse host plants based on inmp (integral membrane protein) gene sequence analysis. This evidence suggests that AlmWB could be associated with phytoplasma strains derived from the adaptation of an original strain to diverse hosts. Healthy plant material and vector control are the main measures applied for AlmWB containment. The first report of a ‘Ca. P. phoenicium’ strain, identical to the species reference strain, on almond in Italy in 2019 opened a worrying scenario on its impact on production of stone fruits and other hosts
Sequencing of the ribosomal protein gene rpl16 from Candidatus Phytoplasma ulmi infecting a historic Ulmus minor
No full textThe aim of this work is to obtain new sequences of ‘Candidatus Phytoplasma ulmi’ useful for the characterization of phytoplasmas
infecting a historic plant of Ulmus minor. At our knowledge, we described for the first time the rpl16 gene sequence of ‘Ca.
P. ulmi’ strain ULW (elm witches’ broom). This gene, positioned downstream the gene rps3, codifies the ribosomal protein L16
RSI-PCR (Restriction Site Insertion-PCR) as molecular tool for specific identification of phytoplasmas in grapevine
No full textIdentification of distinct rpsC single nucleotide polymorphism lineages of Flavescence dorée phytoplasmas co-infecting grapevine plants
No full textDistinct rpsC single nucleotide polymorphism lineages of Flavescence dorée subgroup 16SrV-D phytoplasma co-infect Vitis vinifera L
No full textDuring a survey on grapevine yellows disease complex in vineyards of Lombardy region
(northern Italy), phytoplasmas associated with Flavescence dorée disease were identified in symptomatic
grapevines. Polymerase chain reaction and restriction fragment length polymorphism (RFLP) analyses of
16S rDNA revealed the prevalence of phytoplasmal subgroup 16SrV-D. Bioinformatic analyses of nucleotide
sequences of rplV and rpsC genes, amplified from 16SrV-D phytoplasma infected grapevines and cloned,
underscored the presence of five confirmed rpsC single nucleotide polymorphism (SNP) lineages, determined
by different combination of SNPs at nucleotide positions 29, 365, 680, and 720 of rpsC gene. Virtual
and actual RFLP analyses with the enzyme TaqI validated the presence of these SNPs. Co-infections by up
to four distinct rpsC SNP lineages of 16SrV-D phytoplasma were found in grapevines. These results could
open new perspectives for the study of the ecology and the epidemiology of Flavescence dorée
Molecular genotyping of Candidatus Phytoplasma solani strains identified in different crops in Jordan
Full text linkRecent surveys on phytoplasma-associated diseases in Jordan highlighted that ‘Candidatus Phytoplasma solani’ (CaPsol) is the prevalent phytoplasma throughout the Country. It was largely reported in several crops exhibiting different symptoms, in wild plants (CaPsol plant hosts), and putative insect vectors (Abu Alloush et al., 2023a,b, 2024). To improve the knowledge of CaPsol ecology, this study investigated the genetic diversity within CaPsol strain population identified in multiple crops in Jordan.
MATERIALS AND METHODS
DNA extracts from 51 CaPsol-infected plants of 8 crops, selected from previous studies (Abu Alloush et al., 2023a,b, 2024) (Table 1), were used as templates in direct and nested PCRs for the amplification of tufB, stamp, and vmp1 genes, carried out as previously described (Aryan et al., 2014; Fabre et al., 2011). To genotype CaPsol strains identified in Jordan, nucleotide sequences of obtained PCR products were compared with those of representative CaPsol strains previously described (Pierro et al., 2018; Jamshidi et al., 2022).
RESULTS AND DISCUSSION
Expected amplicons of tufB, stamp, and vmp1 genes were obtained from all the 51 CaPsol-infected plants analyzed. Surprisingly, considering the high genetic diversity generally present within CaPsol strain populations in a specific geographic area (Quaglino et al., 2021; Jamshidi et al., 2022), nucleotide sequence analyses revealed that all 51 CaPsol strains share identical tufB, stamp, and vmp1 gene sequences, highlighting there is no genetic variability in CaPsol strain populations in Jordan. Comparison with previously described CaPsol genotypes revealed that Jordanian CaPsol strains share sequences identical to genotypes tuf b-1 (strain CrHo12_601, Acc. No. KJ469708), St15 (strain P7, Acc. No. FN813258), and Vm53 (strain P7, Acc. No. AM992100), previously identified in Lebanon and Georgia (Caucasus region) and associated with bindweed-related pathosystem (Quaglino et al., 2016; Pierro et al., 2018). Further studies will investigate the diffusion of CaPsol genotype tuf b-1/St15/Vm53 in additional plant hosts and putative insect vectors to study the epidemiological patterns of CaPsol-associated diseases in Jordan
Comparative analysis of acholeplasmataceae genomes highlights the particular genetic repertoire of Candidatus Phytoplasma strains
No full textIntroduction
Acholeplasmataceae comprises the genera Acholeplasma and ‘Ca. Phytoplasma’. Acholeplasmas are described as saprophytic bacteria in general, while phytoplasma strains are characterized as obligate intracellular parasites of the plant phloem associated to diseases in >1,000 plant species. Genome research enables the identification of effector proteins and the reconstruction of the metabolism. The complete genomes of 5 phytoplasma strains and 4 Acholeplasma spp. have been analysed (1,2).
Objectives
Comparative genome analyses provide insights into the evolutionary split of these two genera and the obligate parasitism of phytoplasmas in comparison to the acholeplasmas.
Methods
Different technologies ranging from clone-based Sanger sequencing, pyro-sequencing, sequencing by synthesis and single molecule real time sequencing were applied. Annotation included functional reconstruction and comparative analyses accomplished by gene expression studies.
Results
The conserved gene core of phytoplasmas is also encoded by the analysed 4 acholeplasmas in majority. Phytoplasmas are separated by a particular carboxylic acid metabolism, membrane proteins involved in host interaction and virulence factors.
Conclusion.
Particularities of the phytoplasmas such as the symporter for the uptake of carboxylic acids and their conversion to pyruvate should be interpreted with respect to the Gram+ origin in contrast to genes encoding effectors, which may be derived from horizontal gene transfers
Molecular characterization of phytoplasmas associated with grapevine yellows in Northern Italy
No full textPreliminary data on the presence of grapevine pinot gris virus in Lombardy
No full textGrapevine Pinot Gris virus (GPGV) was identified for the first time in 2012 in Trentino region (northern Italy). Subsequently, GPGV was reported in other Italian regions and in other countries. This Thricovirus, family Betaflexiviridae, was associated with grapevines showing leaves deformation, chloric mottling and puckering. During a survey carried out in six Chardonnay and Pinot noir vineyards in Lombardy, vines showing GPGV-like symptoms were observed.
Total RNAs were extracted from leaves and PCR reaction was performed on cDNA, obtained using random primers and RevertAid M-MuLV Reverse Transcriptase, with primer pairs amplifying three distinct GPGV genomic regions (replicase, movement and coat proteins). PCR products related to movement and coat protein genes were sequenced on both strands, assembled, and compared with GenBank.
GPGV was detected in 14 out of the 29 sampled grapevines; only 3 of these were symptomatic. Utilized primers pairs showed diverse sensitiveness: GPGV was detected in 12 plants using primer pairs for movement and coat protein genes, and in six grapevines using primer pair for replicase. Nucleotide sequences relative to movement (partial) and coat protein genes of Lombardy GPGV isolates share 96.5 to 98% identity with GPGV isolates from Italy, Slovak and Czech.
The finding of this virus in a new area (Lombardy) leads to the consideration that GPGV is widely present in Northern Italy and that further investigation should be done in order to assess its role in the disease aetiology
- …
