Journal of Applied Research in Plant Protection
Year:2018 | Volume:7 | Issue:3 |Papers Count:9

In this work, the changes of antioxidant enzymes activity were studied by spectrophotometry method and expression level of NPR1، FKBP، Chlorophyll a-b binding protein andMetallothionein-like protein genes in two tolerant and susceptible genotypes of maize in response to maize dwarf mosaic virus was investigated by qRTPCR method. Experiment was done in green-house condition by mechanical inoculation and sampling was carried out at different time intervals (0, 1, 9, 24, 72) hors post inoculation (hpi). The results showed a significant increase of peroxidase activity in the tolerant genotype at all sampling times when compared to the susceptible genotype. The highest increase of peroxidase enzyme was recorded at 24hpi for both genotypes in comparison to the control plants, but after 72hpi the rate of peroxidase enzyme was reduced. Catalase enzyme activity was significantly reduced at all sampling time after virus inoculation when compared to the control plants. Gene expression analysis showed that the related expression of NPR1 and MT-LP genes were increased in both genotypes but this increase was significant only in the tolerant genotype. The expression level of FKBP gene in the tolerant genotype increased at the early times after virus inoculation and was decreased more rapidly than susceptible cultivar. The expression changes of Chlorophyll a-b binding gene plants significantly reduced in susceptible plants compared to the control plants. Changes in the antioxidant enzyme activity and gene expression could be used as bio-markers for virus-plant interaction studies and the associated markers may be selected for plant resistance to viral disease.

Diamond back moth (DBM) Plutella xylostella L., currently is one of the most serious insect pests of Brassicaceae in Iran. The larvae of this pest cause damage on these plants by sever defoliation them. In the present study, effectiveness of ionizing radiation by Sterile Insect Technique (SIT) in management of diamond back moth was evaluated. The effect of gamma irradiation on DBM pupae at doses of 100 to 300 Gy on biological parameters of DBM moths was determined when pupae were irradiated. The mean percentage of mortality of irradiated pupae was significantly increased beyond 150 Gy and reached 58. 75% at 300 Gy compared with 32. 89 in control. The longevity of the adult moths significantly decreased beyond 100 Gy. The mean percentages of the egg hatch dose-dependently decreased in crosses between the treated parents (whether one or both parents treated) and reached to zero at 300 Gy. The calculated competition value of the irradiated males was within the acceptable range in rates of 3: 1: 1 and 4: 1: 1 (treated male: normal male: normal female).

Pseudomonas syringae pv. syringae (Pss), the causal agent of bacterial canker of stone fruits, is a dangerous pathogen that attacks more than 200 different plant species. Due to the importance of disease, the purpose of this study was to identify the causal agent of the disease in Kohgiluyeh and Boyerahmad province and comparing the resistance of some cherry cultivars to this pathogen. During 2015-2016, 33 bacterial strains were isolated from stone fruit plants with canker, gummosis, and leaf spot symptoms from different regions of Kohgiluyeh and Boyer-Ahmad province. Isolates were rod-shaped, motile, gram-negative, obligate aerobe, oxidase negative, catalase, levan and tobacco hypersensitive reaction positive, arginine dihydrolase and potato rot negative. The genes responsible for syringomycin synthesis (syrB) and syringomycin secretion (syrD) were detected in all isolates. All strains were able to produce necrosis spots on cherry fruit but showed different virulence. Regarding the phenotypic characteristics, pathogenicity test and PCR results of this study, all isolates were identified as Pss. To study the resistance of cherry plants, Takdaneh Mashhad, Ghaheri and Surati cultivars were selected. There was a significant difference between different cultivars, based on the number of the necrotic lesion on the leaf, length of the necrotic region on the branch and bacterial population in leaf tissue. Among the different cherry cultivars studied in this research, Takdaneh Mashhad cultivar was the most susceptible and Surati cultivar showed the least sensitivity to Pss.

Potato is one of the major Agronomic crops in Kurdistan province. Many fungi have been reported as the causal agents of tuber, crown and root rot and canker on potato plants. The objective of this study was to identify fungal agents associated with tuber, crown and root rot and canker of potato. Samples were collected from diseased plants in East of Kurdistan (Ghorveh and Dehgolan) during cropping season in 2014. Samples were first washed under tap water and then sliced to 0. 5-1 cm pieces, surface sterilized and plated on general or selective culture media. In total 151 isolates were obtained from tuber, crown and roots of infected potatoes and purified using single spore or hyphal tip. Fungal isolates were identified based on morphological and sequence data of ITS, RPB2 and TEF loci. Finally, based on morphologic characters and DNA sequence data 10 species belonging to four genera were identified including Alternaria arborescens, A. alternata, A. atra, A. embellisia, Colletotrichum coccodes, Fusarium equiseti, F. redolens, F. tricinctum, Neocosmospora rubicola and N. haematococca. Among the identified genera, Fusarium with 93 isolates was the most frequent genus.

Longevity, host preference, length of life stages and the number of offspring of Habrobracon hebetor were evaluated on the host larvae of Ephestia kuehniella treated with lethal and sub-lethal doses of Bacillus thuringiensis Experiments were conducted in a completely randomized design under laboratory condition. The number of eggs decreased from 3. 9 in control to 1. 4 and 2. 7 in lethal and sub-lethal doses, respectively. By reducing the number of parasitoid offspring from 3. 7 in control to 0. 6 and 1. 2 in lethal and sub-lethal doses, also the adult parasitoid longevity decreased from 15. 6 days in control to 12. 3 and 13. 7 days in lethal and sub-lethal doses, respectively. In the lethal dose of Bt treatment, duration of embryonic and larval stages of the wasp showed a significant increase compared to control, but pupal stage duration decreased in both lethal and sublethal doses of Bt treatment. Generally, by reducing the usage dose of Bt and avoiding its application during the critical stages of parasitoid life, the efficiency of their use in integrated pest management can be improved.

Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici is one the most important diseases of this plant all over the world and also in Iran. Application of resistant varieties, fungal and bacterial antagonists and long term crop rotation are Principal strategies for the management of this disease. Due to the lack of comprehensive and accurate information about the reaction of different tomato cultivars against Fusarium wilt disease, the current research was conducted for evaluation of resistance in nine prevalent tomato varieties in Iran. Response was assessed by determining disease index, area under disease progress curve (AUDPC), fresh and dry weights of roots and shoots, diameter and length of stems. Based on percent disease index and AUDPC, Walter and Primo Early were determined as immune and very susceptible cultivars respectively and others including Falat, King Star, Monalisa, Petopride5, Super Chef, Super Stone and Super Strain b were susceptible or moderately susceptible against disease. Disease index, AUDPC, dry weights of roots and shoots, fresh weights of roots and shoots, diameter and length of stems in all of the cultivars except Walter, showed significant difference (at p< 0. 01) between inoculated and control plants. Because of least amount of disease severity and AUDPC in Super Strain b, Super Chef and Falat, among nine evaluated tomato varieties, they can be recommended to farmers for better disease management.

Population density of safflower pests and their natural enemies were studied in 14 selected fields, in main cultivation regions for spring and summer safflower of the province, using different sampling techniques, such as insitu counts, sweeping and rearing of adult insects, and considering plant phonology. In total 23 species of pests and 9 species of natural enemies were collected, which the most important ones were as follows. A) Pests feeding bolls: Acanthiophilus helianthi, Chaetorellia carthami (Dip., Tephritidae); Larinus flavescens, L. liliputanus (Col., Curculionidae); Oxycarenus palens, O. hyalipennis (Hem., Lygaeidae) Species 1 to 4 are feeding inside the bolls and species 5 and 6 feeding outside the bolls. The pests, except C. carthami were distributed in different regions of the province. The highest infestation percentage of bolls to A. helianthi, Larinus spp. and Oxycarenus spp. were in the regions of Isfahan (15. 9), Aran va Bidgol (3. 5) and Isfahan (12). B) Pests feeding on other parts of the plant: Uroleucon compositae (Hem., Aphididae); Neoaliturus fenestratus (Hem., Cicadellidae); Chromatomyia horticola (Dip., Agromyzidae) The pests were distributed in different regions of the province. The highest infestation to these pests were in the regions of Ardestan (300 per 10 cm of terminal branch), Isfahan (18 per 100 sweeping net) and Ardestan (11. 2 per 10 1 m2 square). c) Natural enemies of the pests: Antistrophoplex conthurnatus (Hym., Torymidae); Bracon hebetor (Hym., Braconidae); Pachyneuron concolor (Hym., Peteromalidae), Lysiphlebus fabarum (Hym., Braconidae); Pachyneuron concolor (Hym., Pteromalidae); Coccinella septempunctata, Hippodamia variegate (Col., Coccinellidae) Species 1 to 3 are parasitoids of safflower shoot fly, species 4 and 5 are parasitoids of the aphids and species 6 and 7 are coccinelid predators of the aphids. The highest population density of three groups were in the regions of Isfahan (20 per 100 bolls), Ardestan (3. 5 per 100 bolls) and Ardestan (16 per 100 sweeping net).

Stem rot caused by Sclerotinia sclerotiorum, is one of the important diseases of rapeseed, and fungicides are applied for its control. In Iran, carbendazim and tebuconazole are often used for chemical control of the disease. In order to introduce other effective fungicides against the disease, seven fungicides were studied in laboratory conditions and then six of them were applied in the field. In the laboratory conditions, different concentrations of the fungicides showed significant differences (P<0. 01) with control (without fungicide) and caused inhibition of pathogen radial growth on potato dextrose agar medium except chlorothalonil (Daconil® ). Effective concentration (EC50) and minimum inhibitory concentration (MIC) of the fungicides including iprodione + carbendazim (Rovral TS® ), propiconazole (Tilt® ), thiophanate methyle (Topsin M® ), trifloxystrobin+ tebuconazole (Nativo® ), tebuconazole (Folicure® ) and spiroxamine+ tebuconazole+ triadimenol (Falcon® ) was calculated. The EC50 values of these fungicides were 0. 10, 0. 11, 0. 12, 0. 22, 0. 36 and 0. 60 ppm, and MIC values were 1, 5, 1, 10, 10 and 10 ppm respectively. In the field conditions, all fungicides, had significant difference (P<0. 01) with control and decreased the rate of the disease infection and increased the crop yield about 300 to 700 Kg/ha. Nativo® was the most effective fungicide. The duration of plant protection in Nativo® treatment was longer and occurrence of disease symptoms after spraying was later than other treatments. Therefore, these fungicides can be used in rotation with common fungicides.

During different seasons of 2013, a faunistic survey was carried out on oribatid mites (Acari: Oribatida) in Arasbaran forests, north of East Azerbaijan Province of Iran. Mites were extracted from soil and plant litter samples using a Berlese's funnel and cleared in Nesbitt's fluid. Then, they were mounted in Hoyer's medium as microscope slides. In this study, 13 species, belonging to 10 genera and 7 families of poronotic oribatid mites were collected and identified, of which two species for East Azerbaijan Province and two species for the Iran mite fauna were new records which were marked with (*) and (**) respectively. The collected species according to related families are as follows: Lucoppia feideri**, Oribatula (Oribatula) tibialis alifera (Oribatulidae); Scheloribates fimbriatus (Scheloribatidae); Ceratozetella cf. sellnicki (Ceratozetidae); Eupelops cf. eximius, E. acromios, E. torulosus*, E. tardus (Phenopelopidae); Anachipteria cf. deficiens (Achipteriidae); Punctoribates cf. liber (Punctoribatidae); Pilogalumna tenuiclava*, Pergalumna longisetosa**, Galumna (Galumna) karajica (Galumnidae).