فصلنامه گیاه پزشکی
سال سی و هشتم شماره 1 (بهار 1394)

Resistance of 16 S1 pollinator lines derived from two populations with resistance to Rhizoctonia and drought، six cultivars and an open pollinator population were evaluated to a highly virulence isolate of Macrophomona phaseolina، causal agent of charcoal rot of sugar beet in greenhouse condition. Evaluation of the cultivars and lines was carried out in separate experiments. Tooth pikes were used as inoculums. Four-six month plants were inoculated and one month after inoculation، severity of root rot was estimated using a 1-9 standard scale. The results showed different levels of resistance among cultivars and lines. Cultivars Shirin and Jolgae were very susceptible to the disease. Cultivars Flores، Dorothea، Rasta، B8662 and B8618 lines as well as SB19 population were classified in the resistance category with 1 to 3 disease severity indices. Drought resistant lines had a disease severity index ranging from 4. 56 to 7. 36 and were grouped in a susceptible category.

The safflower fly, Acanthiophilus helianthi Rossi, is an important pest of safflower in Isfahan region. In this study, population density and damage of the safflower fly on ten safflower genotypes namely Mexico 37, Mexico 38, Mexico 39, Mexico 50, Mexico 51, KW2, Line5, Line411, Padideh and Goldasht were studied in an experimental field (not using insecticide) during 2012 and 2013. Furthermore, yield indices of ten tested genotypes were studied in a control field (using Chlorpyrifos). The densities of larvae and pupa on Goldasht (7.6 and 8 larvae and pupa/plant) and Line411 (8.8 and 10.4 larvae and pupa/ plant) were lower compared to the other tested genotypes of safflower. In addition, the percentage of infested heads/plant, the percentage of reduced weight of infested head, the percentage of infested seeds/ head, and the percentage of seed loss/infested head on Goldasht and Line411 were lower than that on the other tested genotypes. Yield indices including the number of heads/plant, the number of seeds/ head and the weight of 1000 seeds on Goldasht and Line411 were higher compared to the other tested genotypes. These results indicated that Goldasht and Line411 were the least suitable genotypes to the safflower fly, and these genotypes with a high yield have the potential for use in integrated management program of A. helianthi in safflower fields.

Root knot nematodes (Meloidogyne spp.) are one of the important limiting factors in almond production. Use of resistant rootstocks to plant pathogens is the most effective methods for control of soil-borne pathogens, especially nematodes. In this study, the reaction of several stock and scion composition (Sefeid and Mamaei as scion and GF677, GN15, shorabi 1 peach × almond hybrid and shorabi 2 peach × almond hybrids as rootstock) to root knot nematode (M. javanica) was studied as a randomized complete block design with four replications in greenhouse. The nematodes were added to pots one week after grafting cultivars. Scion growth indices and nematode pathogenicity parameters were evaluated three months after inoculation. Analysis of variance and mean comparison of results showed the susceptibility of all rootstocks, except GN15. Among the susceptible rootstocks to nematode, the highest scion growth was observed on Shorabi 2 peach × almond hybrid. Compatibility of Mamaei (as scion) and Shorabi 1 and Shorabi 2 peach × almond hybrids (as rootstock) increased tolerance to nematode. Collectively, the GN15 and peach × almond hybrids rootstocks were more resistant to root knot nematode than other examined rootstocks. The sensitivity or tolerance of rootstocks to nematodes was affected by the type of grafted variety on different rootstocks.

Movement protein (MP) plays multiple roles in plant pathogenic viruses, especially in cell-to-cell movement for establishing systemic infection. The grapevine fanleaf virus-MP is responsible for cell-to-cell movement of GFLV by introducing tubular structures through the plasmodesmata in host plants. In the present study, genetic diversity of GFLV-MP gene was investigated in Iranian isolates of the virus collected from Markazi, East-Azarbaijan, West-Azarbaijan, Zanjan, Ardabil, and Qazvine provinces. Selection pressure on this gene was furthermore estimated. A total of 245 leaf samples were collected randomly, of which 33 reacted positively in GFLV specific DAS-ELISA Kit. The GFLV-MP gene was amplified by RT-PCR and subsequently was cloned and sequenced. Phylogenetic analysis based on the MP gene uncovered that there were at least two lineages of the GFLV isolates in Iran. Moreover, sequence data analysis showed that the MP gene had constant size of 1044 nucleotides in the all GFLV isolates meaning that this gene did not tolerate any insertion or deletion events. Estimated population genetic parameters revealed that the MP gene of GFLV in Iranian and other isolates of GFLV was under sever purifying (negative) selection pressure, but it was not distributed on the MP gene uniformly.

Pomegranate green aphid, Aphis punicae Pass. is a common pest of pomegranate trees. In this study, the functional response of different age stages (third and fourth larval instars, adult females, male and female 10-days old) of coccinellid predator O. conglobata contaminata (Menetries) was studied to different densities of third and fourth nymphal instars of pomegranate green aphid as prey (at 25 and 27.5°C, 65±5% RH, and 16:8 L: D photoperiod). Densities of 2, 4, 8, 16, 32, 64, 100, and 128 third and fourth nymphal instars of pomegranate green aphid for third and fourth larval instars and densities 8, 16, 32, 64, 100 and 128 for adult females and adult males and females were used and the average feeding at any density was recorded after 24h. Type of functional response was determined using logistic regression and the searching efficiency (a) and handling time (Th) were estimated by nonlinear regression. Type of the functional response at 25 and 27.5oC at all age stages of the predator was type II, and only at 25oC and for the fourth, the response was type III. The Maximum value of the searching efficiency was 0.127 h-1 at 25°C for adult females and the less handling time in this temperature was 0.338h for the fourth larval instar. At 27.5°C, the maximum value of searching efficiency was 0.119 h-1 for the fourth larval instar and the less handling time was 0.275 h related to adult females.

In this study, 223 isolates of Sclerotinia sclerotiorum, the causal agent of cabbage head rot, were collected from different fields in Urmia. Identification of mycelial compatibility groups (MCGs) was done on Potato Dextrose Agar (PDA) culture medium amended with McCormick's red food coloring. A total of 36 MCGs were identified. 23 MCGs (63.88%) had one isolate and the others had more than one isolate. Aggressiveness of the isolates was done on detached cabbage leaves in laboratory conditions and lesion development was determined on treated leaves. All tested isolates were pathogenic on cabbage leaves and disease symptoms were developed, but the aggressiveness was varied greatly among isolates. There was not any correlation between aggressiveness of the isolates, MCGs and isolation location. Isolates obtained from one field were grouped in different MCGs, and there was a difference in aggressiveness, MCGs, and isolation location. The Obtained isolates from one field were grouped in different MCGs, and there was a difference in aggressiveness of isolates within and among MCGs. Results showed that there was a high level of mycelial incompatibility among the Sclerotinia sclerotiorum isolates which were obtained from cabbage fields in Urmia. The high level of mycelial incomtibility indicates the genetic heterogeneity in this fungus and should be considered in management strategies especially using resistant cultivars.

Root and crown gall caused by Rhizobium vitis, is one of the most important diseases of grapevine worldwide. Although there is no efficient chemical control for the disease, various antagonistic bacteria have been studied for its biocontrol. This study was conducted to identify soil inhabiting bacteria in Qazvin province vineyards and to investigate their inhibitory effect on the pathogen. Samples were collected from soil, as well as grape root and crown in 22 areas over the province. Two hundred ten bacterial isolates, obtained from the samples, were grouped and 73 isolates were selected for further study. Identification of the isolates was performed using physiological and biochemical tests. Also, primers Bsub5F and Bsub3R were used to confirm identification of isolates resembling Bacillus subtilis. Ability of the isolates for antibiotic, siderophore, hydrogen cyanide and protease production was studied. Primer pairs PhI2a/PhI2b and PM2/PM7-26R were used to detect PhID and hcnABC genes respectively in fluorescent psuedomonds. Antagonistic effect of five strains, selected from the identified bacteria, on the pathogen was studied on carrot and turnip slices. Based on the results, antagonistic bacteria belonged to Pseudomonas fluorescens biovar I, III and IV, as well as B. subtilis. All strains produced antibiotic and inhibited growth of the pathogen. Also, strains identified as P. fluorescens biovar I، III and IV produced hydrogen cyanide and protease; however, it differed in siderophore production. PhID and hcnABC genes were detected in strains belonging to P. fluorescens biovar I and IV. Two strains belonging to P. fluorescens biovar I, one P. fluorescens biovar IV strain and two B. subtilis strains inhibited gal formation by Rh. vitis on carrot and turnip slices.

Bacterial leaf spot and soft rot is one of the most economically important diseases that affect roots, tubers, leaves and stem of ornamental plants. The disease is caused by a wide range of pectolytic bacteria. To identify the agent of the bacterial leaf spot diseases of ornamental plants in Isfahan province, 70 samples of some ornamental plants showing soft rot and leaf spot symptoms from several various greenhouses were collected. After isolation of bacteria, pathogenicity of isolates was considered by inoculation of their origin host plants. Identification of bacteria was performed using morphological and biochemical tests and the sequence of its 16S rDNA. Results showed that the examined isolates belong to Pectobacterium carotovorum. To the best of our knowledge, this is the first report of a P. carotovorum on ornamental plants in Isfahan province.

In this research, the biological and nutritional indices of Colorado potato beetle, Leptinotarsa decemlineata (Say), were evaluated on 33 potato cultivars in greenhouse conditions. Tubers of cultivars were planted in pots and on each pot one sleeve cage were set up, in which 5 newly emerged female adults were released and the weight of them was measured on the 10th day after releasing. In another experiment, 15 first instar larvae were released on each pot and reared. Amounts of consumed foliage of treatments, larval weight on the 12th day after releasing, duration of larvae and pupae (immature stages) and mortality percentages of these stages were determined. Significant differences were observed for all of the studied traits at 1% level. The highest weight of reared adults was observed on the ‛Sinja’ and‛Bright’ cultivars. The least amount of foliage consuming by larvae was observed on the ‛Satina’ and‛Santana’ cultivars. The least weight of neonate larvae on 12th day after releasing was observed on the ‛Myryam’ and‛Carlita’ cultivars. The longest developmental time (larval and pupal time) on potato cultivars was on the ‛Bridjet’ and‛Delikat’ and the highest larval and pupal mortality were on the ‛Arrancar’ and‛Agata’ cultivars. The least weight of female adults, produced from reared larvae, was observed on the ‛Delikat’ and ‛Romina’ cultivars and the least weight of male adults was observed on the ‛Romina’ and‛Delikat’ cultivars. This research revealed that larval preference is independent from nutritional preference of adults.

The spider mite, Tetranychus turkestani is one of the main pests of cucurbit plants in southern provinces such as Khuzestan. Due to the undesirable effects of using pesticides, this research was performed in order to introduce safe alternative components for the environment. In this study, repellency and anti oviposition effects of Foeniculum vulgare and Citrus lemon essential oils was investigated on mentioned mite females and its predator Orius albidipennis. 2000 ppm of each on essential oil was applied as contact. The most anti ovipositon effect by a mite and its predator was observed on the first day after treatment. The Mean scores of the eggs laid by mite on C. limon and F. vulgare treatment were 0.3±0.48 and 0.5±0.48, respectively. The mean of the lowest oviposition of its predator for mentioned treatments was 1±0.52 and 1.3±0.52, respectively. By passing time and decreasing the essential oils effect, the number of laid eggs increased slowly. According to the repellency index, the essential oil of lemon had more repellency for mite compared to the essential oil of fennel. Whereas. the essential oil of fennel had less repellency for its predator. Therefore, it seems that the essential oil of fennel is a safer component for use in IPM.