To estimate the incidence contamination of fresh pistachio nuts by aflatoxigenic fungi in Iran, nut samples were collected from pistachio orchards in Kerman, Rafsanjan and Isfahan regions.

In recent years, bean common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli (Xap) has caused serious yield losses in several countries. CBB is considered mainly a foliar disease in which symptoms initially appear as small water-soaked spots that then enlarge and become necrotic and usually bordered by a chlorotic zone. Xap epiphytic population community has a critical role in the development of the disease and subsequent epidemics. The epiphytic population of Xap in the field has two major parts; solitary cells (potentially planktonic) and biofilms which are sources for providing and refreshing the solitary cell components. Irrigation type has a significant effect on epiphytic population of Xap. The mean epiphytic population size in the field with an overhead sprinkler irrigation system is significantly higher than populations under furrow irrigation. A significant positive correlation between the epiphytic population size of Xap and disease severity has been reported in both the overhead irrigated (r=0.64) and the furrow irrigated (r= 0.44) fields.

Recently, peach trees showing leaf rolling, little leaf, rosetting, yellowing, bronzing of foliage and tattered and shot-holed leaves symptoms were observed in peach growing areas in the central and north-western regions of Iran. Polymerase chain reaction (PCR) and nested PCR using phytoplasma universal primer pairs P1/Tint, R16F2/R2, PA2F/R and NPA2F/R were employed to detect phytoplasmas. The nested PCR assays detected phytoplasma infections in 51% of symptomatic peach trees in the major peach production areas in East Azerbaijan, Isfahan, ChaharMahal-O-Bakhtiari and Tehran provinces. Restriction fragment length polymorphism (RFLP) analyses of 485 bp fragments amplified using primer pair NPA2F/ R in nested PCR revealed that the phytoplasmas associated with infected peaches were genetically different and they were distinct from phytoplasmas that have been associated with peach and almond witchesÕ-broom diseases in the south of Iran. Sequence analyses of partial 16S rDNA and 16S-23S rDNA intergenic spacer regions demonstrated that ÔCandidatus Phytoplasma aurantifoliaÕ, ÔCa. Phytoplasma solaniÕ and ÔCa. Phytoplasma trifoliiÕ are prevalent in peach growing areas in the central and north-western regions of Iran.

No abstract

In recent years, almond witchesÕ-broom disease has been prevalent in almond growing areas in the centre and south of Iran. Furthermore, almond trees showing different symptoms of phytoplasma diseases such as little leaf, leaf rolling, dieback of branches, rosette and yellowing were observed in the central regions of Iran. DNA isolated from symptomatic almond trees was used to amplify 16S rDNA and 16S-23S rDNA intergenic spacer (IS) fragments by nested polymerase chain reaction (PCR) using phytoplasma universal primer pairs (P1 ⁄ P7, R16F2 ⁄ R2, PA2F ⁄ R and NPA2F ⁄ R). Phytoplasmas were detected in symptomatic almonds in two major almond-growing regions, Isfahan and ChaharMahal-O-Bakhtiari.Restriction fragment length polymorphism analyses of nested PCR products using endonuclease enzymes HpaII and TaqI revealed that phytoplasmas associated with infected almonds are genetically different. Sequence analyses of amplified fragments of 16S rDNA and IS region indicated that the almond phytoplasmas in Iran are closely related to ÔCandidatus (Ca.) Phytoplasma aurantifoliaÕ, ÔCa. Phytoplasma phoeniciumÕ, ÔCa. Phytoplasma solaniÕ and ÔCa. Phytoplasma trifoliiÕ. The phytoplasmas related to ÔCa. Phytoplasma aurantifoliaÕ were more prevalent than other phytoplasmas in the central regions of Iran.

No abstract

A virus causing a disease of tomato, prevalent in the southern provinces of Iran, with symptoms of leafcurling, stunting, reduction of leaf size, leaf corrugation, shortening of internodes and severe reduction in fruit yield, was shown to be transmissible to healthy tomato plants by grafting and by whiteflies (Bemisia tabaci), but not by sap inoculation. Geminivirus DNA was detected in extracts of diseased tomato plants by dot-blot hybridization assays using as probes full-length cloned DNA of Australian, Italian (Sardinian) or Jordanian strains of tomato yellow leaf curl virus (TYLCV). Geminivirus coat protein was detected in whitefly inoculated plants by dot immunobinding assay using polyclonal antibody raised against Jordanian TYLCV. A limited survey using the dot-blot hybridization assay for virus detection indicated the presence of the virus in tomato-growing provinces of southern but not northern Iran. Whitefly transmission experiments to tomato under controlled greenhouse conditions showed that some isolates of TYLCV-like geminiviruses from different parts of Iran differ in symptomatology.

Symptoms suggestive of phytoplasma diseases were observed in infected sweet cherry trees growing in the central regions of Iran. Phytoplasmas were detected in symptomatic trees by the nested polymerase chain reaction (nested PCR) using phytoplasma universal primer pairs (P1⁄Tint, PA2F⁄R, R16F2⁄R2 and NPA2F⁄R). Restriction fragment length polymorphism analyses of 485 bp DNA fragments amplified in nested PCR revealed that different phytoplamas were associated with infected trees. Sequence analyses of phytoplasma 16S rRNA gene and 16S-23S intergenic spacer region indicated that the phytoplasmas related to ÔCa. Phytoplasma asterisÕ and peanut WB group infect sweet cherry trees in these regions. This is the first report of the presence of phytoplasmas related to ÔCa. Phytoplasma asterisÕ and peanut WB group in sweet cherry trees.