Infection experiments of Pyrenophora teres f. maculata on cultivated and wild barley indicate absence of host specificity

European Journal of Plant Pathology - It is important to investigate the possibility of pathogen transmission between cultivated and uncultivated hosts due to the role of the latter in pathogen...     

Variations in nutrient concentration and phytoplankton composition at the euphotic and aphotic layers in the Iranian coastal waters of the Southern Caspian Sea

Temporal variations and regional distributions of dissolved nutrients and their elemental ratios in the Iranian coastal waters of the Southern Caspian Sea were investigated. The data were collected in 1996-97 (Phase I, as a background data and undisturbed ecosystem) and in 2005 (Phase II, as a disturbed ecosystem) at sampling points (from 10 to 100 m depths). In addition to the two main sampling exercises, additional sample collections were carried out during the period of 1994 to 2004 as a long-term study. This study showed that the dissolved inorganic nitrogen/dissolved inorganic phosphorus (DIN/DIP) ratios in the southern Caspian Sea vary within a very narrow range (4.47 to 5.78) within the euphotic and aphotic layers and is by one order of magnitude lower than what have been reported for several other marine ecosystems. Phytoplankton growth seems to be nitrogen limited while the levels of P and Si always remain high. Factor Analysis/Principal Component Analysis (FA/PCA) of the correlation matrix showed that the nitrogen compounds are associated with the main factor accounting for 25.7-26.2% of the total variance for both the sampling periods. During Phase I, the Chrysophyta were the major group, whereas during Phase II the proportion of Chrysophyta in the total community progressively decreased, while the other groups increased.     

Changes in soil properties and plant biodiversity after 12 years of rehabilitating livestock farms in the Hyrcanian Forests

Livestock presence in forest ecosystems is considered a factor in forest destruction in developing countries; therefore, rehabilitation practices following livestock exclusion could be a good way to restore forests. The main purpose of this study was to investigate the changes in the soil properties and plant biodiversity 12 years after applying fencing and planting in the livestock farms in the Hyrcanian Forests of Iran. First, three regions close to each other were selected and then four areas (treatments) were considered in each region: 1. An area under livestock use (L), 2. an enclosed area (E; with fences, established in 2007), 3. a planted area (P; established with Acer velutinum seedlings in 2007), and 4. a control area (C; natural forest); therefore, a total of 12 areas were considered. In each of the 12 areas, three plots (20?×?20 m) were randomly established (a total of 36 plots), and all the vascular plants in the herbaceous layer and woody species seedlings were recorded in order to study the biodiversity of the vegetation cover. One soil sample was taken from each plot to examine the physical and chemical properties of the soil. The results showed that bulk density, pH, electrical conductivity (EC), and available potassium were not significantly different between the C, E, and P treatments. Rehabilitation practices improved the soil pH (P: 6.36?±?0.06, E: 6.59?±?0.08), EC (P: 0.86?±?0.05, E: 0.82?±?0.04 ds cm^?1), total nitrogen (P: 0.31?±?0.001, E: 0.31?±?0.005), available phosphorus (P: 10.13?±?2.22, E: 19.29?±?2.43 mg kg^?1), and available potassium (P: 1369.60?±?31.06, E: 1898.80?±?448.60 mg kg^?1). The Margalef index was lower in the L area and no significant difference was observed between the E and P areas. Since the multivariate analysis (based on the vegetation and soil data) showed that P and E had more similarity to C, these treatments could accelerate the forest restoration process.

     

Population genetic structure of four regional populations of the barley pathogen Pyrenophora teres f. maculata in Iran is characterized by high genetic diversity and sexual recombination

The leaf spot form of the barley disease net blotch, caused by the fungus Pyrenophora teres f. maculata (PTM), is an increasingly important foliar disease of barley. Studies of population genetic structure and reproductive mode are necessary to make predictions of the evolutionary potential of the pathogen. Sources of resistance to PTM have been found in Iranian landraces, which may have the potential to improve plant breeding efforts. However, little is known about the population genetic structure of this fungus in Iran. In this study, we analysed the frequency of the mating type genes to assess the potential for sexual mating of PTM collected from four provinces—Khuzestan, Hamadan, Golestan, and East Azerbaijan—and we investigated the population genetic structure using seven simple sequence repeat markers. High genotype diversity, linkage equilibrium, and equal ratios of mating types frequencies in the PTM populations at Khuzestan and Hamadan support the occurrence of sexual reproduction in these populations, while in Golestan and East Azerbaijan populations, significant gametic disequilibrium and relatively low genotype diversity suggest a higher incidence of clonality or different demographic histories. Unequal mating type frequencies in Golestan confirm a predominance of asexual reproduction. Finally, we found significant evidence for strong population structure with most of the genetic variation represented within regional populations (89%). Overall, our study provides evidence for high genetic variation in Iranian PTM populations, which may be the basis for rapid adaptive evolution in this pathosystem. This highlights the need for integrated efforts to control the disease.     

Immunomodulatory effect of cimetidine in common carp (Cyprinus carpio L.)

The main indication of cimetidine is being H₂-receptor antagonist, but studies suggest that cimetidine may also act as a non-specific stimulant of cell-mediated immunity and immunomodulator. In order to determine the immunomodulatory effect of dietary intake of cimetidine in the common carp (100 ± 10 g), subjects were fed diets containing 0 (control), 50, 100 and 200 mg cimetidine kg^?1 of dry diet for a period of 6 weeks. TLC and NBT assays were significantly (P < 0.05) stimulated in cimetidine-supplemented groups displaying the highest value in 200 mg kg^?1 group. A decrease (P < 0.05) in cortisol and ACH50 value was recorded in fish treated with cimetidine. Serum protein, albumin and serum globulin levels were not significantly changed. The findings of the present investigation suggest that the incorporation of cimetidine in the diet of common carp enhances the non-specific immunity.