In this study, Russian olive trees exhibiting witches’-broom symptoms were collected from urban green areas in Tabriz, in the northwest of Iran. PCR analysis confirmed that phytoplasma caused the disease and, according to the resulting Sanger sequencing electropherogram, a mixed infection with two or more phytoplasma species within the Russian olive trees was revealed. Next-generation sequencing analyses, using the Illumina method, were performed on total DNA from the infected Russian olive plants to recognize the microbial genomic content and assemble the whole genome of the causative pathogen(s). The use of MetaphlAn2 and Kraken2 to analyze species composition revealed the very diverse and unique compositions of different Prokaryotic and Eukaryotic species within the infected plants. Several bacteria and fungi were discovered inside the samples, among which Mycoplasmatota was significantly dominating. Interestingly, the results also revealed a high level of endosymbiotic bacteria and Archaea (Methanobacteria) genome contents within the samples. Bowtie2, metaSPAdes, and CD-HIT pipelines were used to perform the initial genome assembly, and the whole genome of the notable phytoplasma species was assembled and submitted to Genbank.
Genetic diversity and population structure among 29 isolates of Ascochyta rabiei (AR) obtained from diseased chickpea plants in six different geographical origins in Iran was characterized by MAT and rep‐PCR (BOX/ERIC/REP) markers. Both mating types were found in all six populations, and the frequencies of mating types were variable between populations. The majority of the isolates belonged to Mat1‐1 (58.12%) with the remainder (41.88%) being Mat1‐2. A dendrogram was calculated with Jaccard's similarity coefficients with unweighted pair group method clustering (UPGMA) for the combination of rep‐PCR results, AR strains were differentiated into four clusters (A–D) at 60% similarity level. ERIC, REP and BOX showed a total of 19, 37 and 24 alleles per locus, respectively. Gene diversity (He) and Shannon's information index (I) were the highest in the REP (He = 0.82; I = 2.11), while the lowest values were estimated for the ERIC (He = 0.42; I = 1.3). Our result showed that among the three techniques studied, REP‐PCR produced the most complex amplified banding patterns, which reflected a high degree of diversity among the Iranian AR strains. ERIC‐PCR was the least discriminating method, and BOX‐PCR was intermediate. To the best our knowledge, this is first study of assessment of genetic diversity of AR isolates by rep‐PCR markers.
Phytoplasmas are non-cultivable, wall-less bacteria belonging to the class Mollicutes. They are classified as ʻCandidatus Phytoplasmaʼ species, all of which are plant pathogens. 'Ca. Phytoplasma phoenicium' is one of the most important phytoplasmas that infects various herbaceous and trees throughout the Middle East and Mediterranean countries. 'Ca. P. phoenicium' belongs to the 16SrIX phytoplasma group (The IRPCM Phytoplasma/Spiroplasma working team-Phytolasma taxonomy group, 2004) and shares several genetic
Chickpea (Cicer arietinum), a cool season grain legume grown on a surface of 11million ha with worldwide production of about 9 million tons, is cultivated in more than 45 countries throughout the world including Iran where it is grown mostly in rainfed areas and on marginal lands in the province of West Azarbayjan. Ascochyta blight is perhaps the most frequent and damaging disease of chickpea worldwide. It is caused by Ascochyta Rabiei; a fungus that selectively attacks chickpea. Ten isolated bacteria from chickpea plants rhizosphere soil, were evaluated in vitro as a potential antagonist of fungal pathogen. Sequencing of 16S rDNA and comparison with Gen Bank database of sequences revealed that antagonistic strains belong to the species Pseudomonas fluorescens (three strains), P. putida (three strains), Bulkholderia multivorans (three strains) and Mezorhizobium ciceri (one strain). All the strains significantly inhibited A. rabiei, and resulted in >30% inhibition on PDA.
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