Iranian Plant Protection Research
Year:2008 | Volume:22 | Issue:1|Papers Count:10

In order to identify and determine the distribution of Heterodera species, 130 soil and infected root samples were collected from sugar beet fields in Mashhad region. Soil samples were washed and nematodes were separated from soils and tissues by De Grisse and Fenwick methods. Prepared slides were studied based on the morphological and morphometrical characteristics. In this study, Heterodera schachtii, H. trifolii, H. rosii, H. avenae, H. mani, H. iri, H. carotae, H. cruciferae were identified from different sugar beet fields. Two species were separated from soil of sugar beet fields and also roots of carrot and rape (Eruca sativa), respectively. Frequency and distribution of the first two species (H. schachtii and H. trifolii) were more than other species and they were found in the soil as well as root samples.

Rhizomania is one of the most economically important diseases of sugarbeet that causes a severe loss in root yield of sugarbeet in our country. Three types of BNYVV are known to exist, namely the A, B and P types. Distribution of type B in the world is in second rank after type A. As diagnosis of type B through serological methods or RT-PCR-RFLP are very costly, so we tried to use RT-PCR test in our research. Samples with rhizomania symptoms were collected from fields in Razavi and Nothern Khorasan provinces. Infection of samples was confirmed by DAS-ELISA. For RT-PCR experiments, at first we followed the previous protocol which has been set for the recognition of type A, but we could not get positive answer, so we changed RT-PCR protocol. After extraction of total RNA by PEG6000 percipitation method, cDNA of virus synthesized by using reverse specific primer (from TGB region of RNA2 of viral genome). PCR was performed with specific forward and reverse primers. PCR products were separated in 1.5% agarose gel and a 178bp band which was expected for type B appeared in 3 out of 20 samples which have been tested. This is the first report of the detection of type B of BNYVV through RT-PCR by using specific primers.

The low breeding capacity and registration of commercial strains of Agaricus bisporus are the most important challenges for mushroom breeders. AFLP fingerprinting can be a promising solution for registration of Agaricus bisporus starins. This research has examined AFLPs potential to molecular breeding of A. bisporus with an emphasis on genetic fingerprinting of the bred strains. The AFLP band patterns of nine bred strains were prepared. Monomorph and polymorph bands were numbered and relevant data were transferred to PoPGene32 software for dominant markers. Dendrogram was drawn by using JMP4 software. Overall 55 scorable bands were identified from which 20% were poly-morph and 80% were mono-morph. The relevant dendrogram showed different three groups at a similarity coefficient of 80%. The results showed that AFLP is a potent technique for genetic fingerprinting of the button mushroom strains and also for providing a molecular certificate for each bred strain, because in this research with one marker site (only one pair of primer out of 16 possible combinations), it was possible to distinguish individuals. The result also showed that the AFLP profiling is replicable and reliable.

By reaction of cyanoric chloride and isopropyl amine under -10oC temperature, 4-isopropil Amin, 2,6-  dichlorotriazine was obtained. In the second stage, through the reaction of this product with ethyl amine, the product2-ethyamine 4-isopropilamine-6-chlorotriazine was resulted. In the last stage by reaction of the product of second stage with sodium methyl mercaptid under -10oC temperature under basic conditions, the powder form of Ametryn Technical was produced. This herbicide is water soluble and absorbed by surface of the young leaf of plants. These compound interferers with photosynthesis by dissolving the cell membrane and diminishing plant's vital materials leading to die the treated plant.

Thirty-four isolates of U. necator were taken from diseased grapes from different vineyards in Khorassan province. Sample was collected in June, July and August 2003 from the same plants. Young plant leaves reproduced through micro propagation method were used to obtain single spore isolates. A minimum of 10 leaves were used to produce fungi biomass. Amount of fungi biomass production 12 days after inoculation were changed in a range of 6 to 38 mg depending on concerned isolates. DNA from these isolates were extracted and genetic variation among all isolates were assessed with 22 primers by using RAPD technique. Cluster analysis based on the 126 RAPD fragments obtained using 22 primers revealed two very distinct groups, one group containing 11 isolates from the first sampling, the second group containing all the remaining isolates. Isolates clustered in the first group displayed 47 RAPD fragments specific to them. These isolates did not exhibit 79 RAPD fragments present in all other isolates. Molecular data suggested that isolates clustering in two groups represent two different biotypes of U. necator, which are likely to be genetically isolated.

Sequences of the intergenic spacer between the 28S and the 5S rDNA genes (IGS 1) were compared for six Puccinia striiformis f. sp. tritici isolates, of different geographic origins, virulence spectra and AFLP groups. Two PCR products (IGS 1A and IGS 1B, of 1.3 and 1.1 kb, respectively) were recovered from all spore multiplications. The analysis of IGS 1A or IGS 1B showed that a low mutational polymorphism existed among the six isolates (from 0 to 1.5%). The comparison of IGS 1A and IGS 1B to each other showed that the polymorphism between the two types of IGS was due to a length polymorphism consisting of about 200 bp insertion/deletion located in the repeated region. Two hypotheses can be proposed to explain the coexistence of two different IGS 1 types within one isolate: either each nucleus of this dikaryotic fungus contains one type of IGS 1 or there are two discrete ribosomal units resulting from recombination in the same nucleus.

The effect of six antibacterial materials including, Penicillin, Tetracycline, Coamoxyclave, Daxycillin, Cephtyzoxim, and Cephtryaxon, was studied on adults and nymphs of Bemisia tabaci Gennadius, each in three concentrations of 0.05, 0.1, and 0.2%. The results indicated that they had no significant effect on survival percentage of egg, nymphal instars, and adults, mean longevity, and adult’s eclusion percentage. Of the studied antibiotics, Cephtryaxon and Cephtyzoxim had the greatest effect on fecundity. There was positive relationship between antibiotics concentration and their effect on fecundity. Application of antibiotics caused the significant decrease in length and width of the nymph. Antibiotics application on the adults increased the number of male progeny, but when the materials were applied on the nymphs, the sex of progeny had no significant difference to control. In trials of antibiotics application on the nymphs, all the materials except penicillin had significant effect on survival percentage of different nymphal instars and adult’s eclusion; as the effect of Cephtryaxon, Cephtyzoxim, and Daxycillin was determined greater than other ones. Unlike the longevity, mean fecundity of adults was significantly lower than control. Comparision of the results of antibiotics application on adults and nymphs indicated that the antibiotics effects on the nymphal instars were more that on the adults. The antibiotics had no significant effect on nymphal survival, when were applied on adults contrary to the nymphal instars. Also, the effect of antibiotics on fecundity, when were applied on the nymphs, was more than the adults. Since Encarsia formosa Gahan (Hymenoptera: Aphelinidae) is an efficient parasitoid on aleyrodids, in order to studying the possibility of integrated control of B. tabaci by antibacterial materials and E. formosa, the antibiotics effects were evaluated on the parasitoid. The studied morphological and biological characteristics were body length size, and head capsule width of larvae and adults, longevity, fecundity and sex ratio of the first and second generations. Antibiotics affected on the all the mentioned morphological and biological characteristics significantly. Of the studied antibiotics, Cephtryaxon, and Cephtyzoxim had lower effect on the parasitoid’s sex ratio; therefore, integrating of the two antibiotics with E. formosa is probably possible in IPM programs.

One of the most important cotton diseases in Iran is post emergence cotton seedling damping –off which causes significant losses annually. The most important agents of these diseases in Iran are Pythium spp. and Rhizoctonia solani. In this study the possibility of biological control using bacterial antagonists in the field was investigated. Five bacterial isolates (three belonging to Pseudomonas fluorescens and two Bacillus spp.) were selected for this study based on their performances in the greenhouse experiments. Two cotton varieties (Sahel and Saiokra) were used in this experiment and seed coating procedure was followed for bacterial application. The study was carried out in a cotton fields in Golestan province during 1381 and 1382 (2002 and 2003) growing seasons. Two commonly used fungicides (Carbendazim and Carboxin thiram) were also used for comparison. The efficacy of bacterial isolates and fungicides was evaluated based on the number of healthy seedlings (stand) 15, 30, 45 and 60 days after sowing. Results indicated that three bacterial isolates (one Pseudomonas fluorescens and two Bacillus spp.) along with fungicides showed the most effectiveness in control of cotton seedlings against damping-off disease in both years. The results obtained for two cotton varieties in different years varied but the differences were not statistically significant. The differences in the obtained results in different years may be due to the variation in environmental conditions. The overall result of this study shows the possibility of using antagonistic bacteria and fungicides in the cotton fields as biological control agents (BCA).

Verticillium dahliae is the causal agent of verticillium wilt of olive trees in Golestan province. Based on sampling of twigs from various area of olive orchards such as: Hashem-Abad, Kordkoy Road, Ali- Abad Road, Shastkalate, Toshan, Karkande and Alang. Defoliate and Non-defoliate isolates were determined by significant differences in reaction of optimum temperature, dimension of microsclerotia, reaction of cotton (CV Varamin) seedling, and pathogenicity of olive (CV Zard-Roghani) twigs. Elongated microsclerotia produced by defoliate isolates in Water-agar medium rather than by non-defoliate isolates. Dimension of microsclerotia in olive isolates was 112×28m significantly larger than cotton isolates 58×21m. Optimum temperature in defoliate and non-defoliate isolates were 27oc and 23oc respectively. Defoliate isolates of cotton on Varamin cultivar seedlings occured severe wilting, while non-defoliate isolates showed symptom of chlorosis with mild wilting. In pathogenicity test with defoliate isolate on the twigs of olive trees Zard-Roghani cultivar caused rolling and twisting of leaves.