Search

Japanese quince trees are grown as ornamental plants in Iran, in parks and in orchards close to stone fruit and pome fruit trees. Shoots of Japanese quince (Chaenomeles japonica) showing sunken brown canker symptoms were observed and collected near Sari, the center of Mazandaran province in the North of Iran, during the 2016 growing season. Gram negative bacteria isolated from symptomatic tissues were similar to Pseudomonas syringae pv. syringae (Pss) were pathogenic on Japanese quince and on quince (Cydonia oblonga) seedlings after artificial inoculation, and were re-isolated from diseased hosts. Phylogenetic tree construction using partial sequences of ITS and rpoD genes showed that the Japanese quince isolates were in the same clade as Pss strains. The isolates had ice nucleation activity, and the InaK gene was amplified successfully. According to the results of phenotypic and genotypic characteristics, genomic DNA fingerprinting using REP-PCR, BOX-PCR and IS50-PCR and isolation of total cell proteins, we conclude that Pss is the causal agent of canker of the Japanese quince trees. Therefore, Japanese quince is a new host for Pss causing bacterial canker on many different host plants.

Grapevine virus A (GVA), the type species of the Vitivirus genus, is one of the causal agents of the Kober stem grooving disease of the rugose wood complex and one of the most frequently detected viruses in grapevine. There is little information on GVA gene(s) marker useful for phylogenetic analysis. To this aim, a total of 403 leaf samples were collected from vineyards of East and West Azarbaijan provinces in the Northwestern provinces of Iran during 2014–2016 and tested by DAS-ELISA and RT-PCR using ORF5-specific primers. GVA was detected in 56 symptomatic samples, corresponding to 14% of infection, while it was not detected in asymptomatic samples. The ORF5 (p10) protein sequence of eight Iranian isolates was compared to other vitiviruses, showing that the most conserved region resides in the N-terminus, carrying an arginine-rich motif followed by a zinc-finger motif. Next, to define a robust phylogenetic marker representative of the whole genome sequence suitable for phylogenetic and evolutionary studies, phylogenetic trees based on the full genome sequences of all the available GVA isolates and on individual genomic regions were constructed and compared. ORF1, which encodes the RNA-dependent RNA polymerase, was found to be the best phylogenetic marker for GVA classification and evolution studies. These results can be used for further research on phylogenetic analyses, evolution history, epidemiology, and etiology of rugose wood complex, and to identify control measures against GVA and other vitiviruses.

The bacterial soft rot and vascular wilt of sugar beet are the major diseases of sugar crops globally induced by Pectobacterium betavasculorum and P. carotovorum subsp. carotovorum (Pcc). The control of this bacterial disease is a severe problem, and only a few copper-based chemical bactericides are available for this disease. Because of the limitations of chemicals to control plant bacterial pathogens, the essential oils and extracts have been considered one of the best alternative strategies for their control. In this study, twenty-seven essential oils and twenty-nine plant extracts were extracted and evaluated for their antibacterial activities against Pectobacterium betavasculorum isolate C3, using the agar diffusion method at 0.01%, 0.1%, and 100% (v/v). Pure Pimpinella anisum L. oil exhibited the most anti-bacterial activity among three different concentrations of essential oils and extracts, followed by Thymus vulgaris L. oil and Rosa multiflora Thunb. extract. The efficacy of effective essential oils and extracts on Ic1 cultivar of sugar beet seeds germination and seedling growth in vivo also were tested. The seed germination of the Ic1 cultivar was inhibited at all the concentrations of essential oils used. Only extracts of Rosa multiflora Thunb., Brassica oleracea L., Lactuca serriola L., Salvia rosmarinus Spenn., Syzygium aromaticum (L.) Merr. and L.M.Perry, Eucalyptus globulus Labill., and essential oils of Ocmium basilicum L., Pimpinella anisum L., and Mentha× piperita L.L. in 0.1% concentration had no inhibition on seed germination and could improve seedling growth. This is the first report of the antibacterial activity of essential oils and extracts on Pectobacterium betavasculorum.

Using double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), Cucumber mosaic virus (CMV) was detected in 31 out of 132 symptomatic leaf samples collected from different hosts of Urmia province of Iran, during 2011-2012. In biological assays, five different host isolates caused severe mosaic in Nicotiana species and Capsicum annum without significant difference in severity. Based on phylogenetic analysis of coat protein nucleotide and deduced amino acid sequence, two isolates were clustered into subgroup IA, while other three isolates were grouped into IB subgroup of CMV. All Urmian isolates shared a common MspI, and no EcoRI and BsuRI restriction sites. In contrast to S-IA isolates, the second MspI site was found at 473-476 position of only S-IB isolates, which could be used to differentiate two S-IA and S-IB subgroups. Here, we report the first case of Abutilon theophrasti infection, as a new reservoir weed host for CMV in the world.

Bean is considered as one of the most important legumes around the world. Viral diseases are a major yield reducing factor in bean production. Bean samples with virus-like symptoms like severe or mild mosaic, vein banding, leaf curling, blistering and necrosis were collected from different bean fields in Urmia (Northwest of Iran) during the growing seasons of 2013 and 2014. Bean common mosaic virus (BCMV), Bean common mosaic necrosis virus (BCMNV), Bean yellow mosaic virus (BYMV), Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV), Tomato mosaic virus (ToMV) and Tomato yellow leaf curl virus (TYLCV) were detected by double antibody sandwich enzyme-linked-immunosorbent assay. Mixed infection of BCMV and BCMNV were found. BCMNV was the most frequent virus in this region whereas BYMV and TYLCV were each detected just in one sample. This is the first report of BCMNV, BCMV, BYMV, TSWV, TMV and TYLCV incidence on bean in Urmia, Iran.

During field surveys in 2013 and 2014, about 14 weed plants showing phytoplasma diseases symptoms including yellowing and witches’broom were collected and tested by polymerase chain reaction (PCR) using universal primers for 16SrRNA starting by primer pairs P1/P7 in first round PCR followed by primer pair R16F2n/R16R2 in nested PCR. The detected phytoplasmas were characterized and differentiated through sequence analysis of PCR-amplified rDNA and virtual restriction fragment length polymorphism (RFLP). The phytoplasmas detected in symptomatic horseweed (Erigeron canadensis L.), common madder (Rubia tinctorum L.), Johnson grass (Sorghum halepense [L.] Pers.) and Sophora root (Sophora alopecuroides L.) were identified as members of the clover proliferation group (16SrVI group) by construction of phylogenetic trees. Further analysis by virtual RFLP classified the phytoplasmas of Erigeron canadensis L. and Sorghum halepense L. in subgroup 16SrVI-A and phytoplasmas of Rubia tinctorum L. and Sophora alpecuriodes L. in subgroup 16SrVI-D. This is the first report on the occurrence of phytoplasma diseases of weeds in west Azarbaijan, Iran.

A survey was conducted in Qazvin province in the North of Iran, to determine the incidence of tomato viruses including: Tobacco mosaic virus (TMV), Tomato yellow leaf curl virus (TYLCV), Tomato chlorotic spot virus (TCSV), Tomato bushy stunt virus (TBSV), Tomato spotted wilt virus (TSWV), Tomato ring spot virus (ToRSV), Tomato aspermy virus (TAV), Potato virus Y (PVY), Beet curly top virus (BCTV), and Cucumber mosaic virus (CMV). A total of 742 tomato symptomatic samples were collected during the summer of 2007 in five regions of Qazvin province (Qazvin, Takestan, Boeen-Zahra, Alborz and Abiyek) and tested by enzyme-linked immunosorbent assay (ELISA). TSWV was detected in Alborz (4.4 %) and Abiyek (3.57%) regions but TMV and CMV were detected in all five regions. The greatest and least incidence of tomato viruses were recorded in Alborz (40.7 %) and Takestan (11.1 %), respectively. The presence of these viruses was also evaluated in the weed hosts as natural sources of plant viruses. The greatest and least incidence of tomato viruses in weed hosts were recorded in Boeen-Zahra (25.6 %) and Qazvin (12.8 %), respectively. TSWV was not detected in weeds. Transmission tests demonstrated that Thrips tabaci acts as TSWV carrier and Myzus persicae and Aphis gossypii were CMV carriers. Seed transmission tests were positive for TMV (13 tomato seedlings from 100 seedlings), but no TSWV transmission was observed through the seeds of infected tomato fruits.