Sclerotinia sclerotiorum (Lib.) de Bary, the causal agent of Sclerotinia stem rot, is one of the most important pathogens of Brassica napus L. in northern Iran. In this study, 13 mycelial compatibility groups (MCGs) of the fungus were identified among 31 isolates sampled from four regions of Mazandaran province, Iran. Effective fungicides are useful in the integrated management of the disease. So, the effect of tebuconazole, propiconazole, cyproconazole, and Rovral-TS at five doses (0.0001, 0.001, 0.01, 0.1, and 1 ppm) was studied on the growth inhibition of S. sclerotiorum as in vitro tests. Maximum inhibition (100%) of S. sclerotiorum mycelial growth was obtained by the highest dose (1 ppm) of all tested fungicides, as well as by the doses of 0.1 and 0.01 ppm of propiconazole, cyproconazole, and tebuconazole. In this investigation, the reaction of S. sclerotiorum isolates belonging to different MCGs was evaluated against tebuconazole, propiconazole, cyproconazole, and Rovral-TS at their EC50 ranges. The results revealed that there was high variation of S. sclerotiorum MCGs against different fungicides. The inhibition percentage varied between 4.29% and 71.72%.
Because of the importance of ornamental plants culture in north of Iran, and the outbreak of suspicious symptoms of phytoplasma diseases on these plants, a study was carried out in order to detect and identify phytoplasmas associated with them. The presence of phytoplasma in samples of cockscomb, tagetes and rose plants was shown by direct and nested-PCR assays using the phytoplasma-specific primers, P1/P7 and R16F2n/R2. Sequences of cockscomb, Indian marigold and rose phytoplasmas have high homology with the members of aster yellows phytoplasma group (16SrI). Phylogenetic analysis showed that cockscomb, tagetes and rose phytoplasmas are closely related to 16SrI-M the first one and 16SrI-B the latter two, respectively. To our knowledge, this is the first report of a member of 16SrI group phytoplasma infection in cockscomb in Iran. Moreover, the present study is the first report of phytoplasma disease outbreak on rose in north of Iran by subgroup classification of the associated phytoplasma.
In order to gain insight into molecular and physiological changes in apple trees during compatible interaction with two 'Candidatus Phytoplasma mali' strains (AP and AT), cDNA-Amplified Fragment Length Polymorphism (cDNA-AFLP) technique was used. A rootstock of apple (MM106) susceptible to 'Ca. P. mali' was used to extend the range of the potential host responses by the maximum number of identified genes that will be deregulated by phytoplasma in apple. Gene expression comparisons were studied in three directions: healthy versus infected samples, symptomatic versus nonsymptomatic sample, and AP-infected versus ATinfected sample. Forty-five genes whose steady-state levels of expression significantly changed in response to phytoplasma infection were identified. Among their partial cDNA sequences, only 27 showed similarity to DNA or protein data bases; of these, 18 were related to known genes in plants, and the rest were related to unknown or hypothetical proteins. Eighteen out of 45 did not show any similarity with sequences in data bases (potential novel genes). Quantitative real-time RT-PCR (qRT-PCR) was used to confirm differential expression of AFLP identified genes, and showed the similar profile expression for 11 known genes among 18, and for 13 unknown, hypothetical or novel genes among 27. Changes in gene expression involved a wide spectrum of biological functions, including processes of metabolism, cell defence, senescence, photosynthesis, transport, transcription, signal transduction and protein synthesis. This is the first study of global gene profiling in plants in response to phytoplasma infections using cDNA-AFLP, and a model is proposed to explain the mode of action of the 'Ca. P. mali' in apple.
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