Introduction of some new endophytic bacteria from Bacillus and Streptomyces genera as successful biocontrol agents against Sclerotium rolfsii

Endophytic bacteria live inside plant tissues without causing disease and not only promote plant growth but can also protect plants against plant pathogens. During 2010–2011 crop years, some endophytic bacteria were collected and are then biochemically and molecularly identified (16srRNA) from bean farms of East Azarbaijan, Iran. Among these bacteria isolates, four isolates from Bacillus genera and four isolates from Streptomyces genera were selected for evaluation of their ability for biocontrol of Sclerotium rolfsii in laboratory and glasshouse conditions. Except one isolate named Streptomyces parvus, the rest of isolates could significantly inhibit mycelial growth in dual culture on PDA medium. All seven selected isolates showed significant inhibition in disease treatments in glasshouse experiments. Biological traits, such as length, wet and dry weight of roots and stems in endophytic bacterial treatment showed no differences with healthy control.     

Expression analysis of dehydrin multigene family across tolerant and susceptible barley (Hordeum vulgare L.) genotypes in response to terminal drought stress

Dehydrins are one of the characteristic families of plant proteins that usually accumulate in response to drought. In the present study, gene expressions of dehydrin multigene family (13 genes) were examined in flag leaves of tolerant (Yousef) and susceptible (Moroco) barley varieties under terminal drought to characterize the involvement of dehydrins in the adaptive processes. The stomatal conductance, RWC, and Chl a, b contents had more reduction in Moroco than the Yousef which has more elevated osmotic adjustment. Drought stress increased significantly MDA and electrolyte leakage levels, but greater in Moroco, indicating a poor protection of cell and cytoplasmic membrane in this variety. Yousef variety had no reduction in grain yield under drought condition. Five genes (Dhn1, Dhn3, Dhn5, Dhn7 and Dhn9) were exclusively induced in Yousef under drought stress. In the stress condition, relative gene expression of Dhn3, Dhn9 had the direct correlations (P < 0.05) with Chl a, b contents, osmotic adjustment, stomatal conductance, plant biomass and grain yield, and the negative correlations (P < 0.05) with MDA and electrolyte leakage levels. The results supported the impending functional roles of dehydrin K_n and particularly Y_nSK_n types in dehydration tolerance of barley during the reproductive stage.     

Effect of penconazole and drought stress on the essential oil composition and gene expression of Mentha pulegium L. (Lamiaceae) at flowering stage

Effect of penconazole (PEN) on the expression level of two genes in the biosynthesis pathway of monoterpenes, isopiperitenone reductase (iPR) and pulegone reductase (PR), and essential oil (EO) compounds were studied at flowering stage of Mentha pulegium L. under drought stress. Plants were grown with different levels of field capacity (100 and 50 %) with or without PEN (15 mg l^?1). Results showed that drought stress decreased the growth and productivity parameters. PEN treatment to drought-stressed plants decreased the negative effects of drought stress on these parameters. The EO yield increased by about 1.6 times under drought stress, and the highest amount of EO was obtained in drought-stressed with PEN. Drought stress increased pulegone and decreased menthone percentage, and the highest pulegone percentage (78.2 % of total constituents) was obtained in drought-stressed with PEN treatment. Semi-quantitative RT-PCR showed drought stress increased the expression level of iPR and PR genes. PEN treatment promoted the impact of drought stress on iPR gene expression and repressed PR gene expression. Our results suggest that PEN may be a useful tool for the regulation of monoterpene metabolism in M. pulegium under stress condition.     

A new species of Xiphinema americanum group (Nematoda: Longidoridae) from Iran,with additional data on three known species

Systematic Parasitology - One new and three known species of the genus Xiphinema from the rhizosphere of fruit trees and rose shrubs in East Azarbaijan province, Iran, are presented based on the...     

Effects of Iso-osmotic Concentrations of NaCl and Mannitol on some Metabolic Activity in Calluses of Two Salicornia species

The comparative effects of salinity and drought on activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), and polyphenol oxidase (PPO) and contents of protein, proline, hydrogen peroxide, malondialdehyde (MDA), and carotenoids were studied in calluses of Salicornia persica and Salicornia europaea. Calluses were cultured on Murashige and Skoog medium (MS medium) containing iso-osmotic concentrations of NaCl (100, 300, and 600 mM) and mannitol (200, 500, and 1000 mM). Proline content increased in calluses of both species under NaCl- and mannitol-induced stresses. Under both stresses, S. persica accumulated higher amounts of protein as compared to S. europaea. Under both stresses, protein content in S. persica decreased in comparison to control. Antioxidant enzyme activities showed different trends in the two Salicornia species under salt and drought stresses but were higher in S. europaea than in S. persica. Changes of hydrogen peroxide and MDA contents of calluses subjected to salt stress followed a pattern different from that observed under drought stress. MDA content showed similar changes to hydrogen peroxide content. Carotenoid content decreased in both species under both stresses. Overall, at the cellular level, S. europaea calluses were more tolerant to both NaCl- and mannitol-induced stresses than calluses of S. persica.     

Central role of salicylic acid in resistance of safflower (Carthamus tinctorius L.) against salinity

The effects of salicylic acid (SA) on growth parameters and enzyme activities were investigated in salt-stressed safflower (Carthamus tinctorius L.). Twenty-five days after sowing, seedlings were treated with NaCl (0, 100, and 200?mM) and SA (1?mM), and were harvested at 21 days after treatments. Results showed that some growth parameters decreased under salinity, while malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) content, phenolic compounds, and some enzyme activities increased. SA application increased some growth parameters, MDA and H₂O₂ content, and enzyme activities except catalase (CAT), which was different from the other enzymes and SA significantly reduced CAT activity in plants. These results suggest that SA-induced tolerance to salinity may be related to regulation of antioxidative responses and H₂O₂ level. Our study suggested that the resistant safflower can direct reactive oxygen species from a threat to an opportunity by using SA. Therefore, exogenous application of SA played this role through regulation of the antioxidant system.     

Betaine Elevates Ovarian Antioxidant Enzyme Activities and Demonstrates Methyl Donor Effect in Non-Pregnant Rats

Chronic alcoholism leads to infertility in male and female rats, and antioxidant enzymes form the first line against oxidative stress in organisms. In recent years, betaine has shown beneficial effects on various tissues, and this study has attempted to clarify antioxidant and methyl donor properties of betaine in the rat ovary. For this purpose, the sexually matured Sprague-Dawley female rats were divided into Control, Ethanol (EtOH), Betaine, and Betaine?+?EtOH groups. Administration of betaine in Betaine?+?EtOH group significantly increased CAT activity when compared to the other groups (P?<?0.05). GPx activity increased significantly in Betaine and Betaine?+?EtOH groups as compared to controls (P?<?0.05). Interestingly, GPx and CAT activities insignificantly increased (in order compensatory) in EtOH group to suppress oxidative stress. In contrast, SOD activity decreased insignificantly in EtOH group compared to Betaine?+?EtOH and control groups (P?>?0.05). TBARS concentration (as a lipid peroxidation marker) significantly increased in ethanol-treated rats as compared to controls, while total homocysteine concentration significantly decreased in betaine-treated rats in comparison with EtOH group. Regarding to oestrous cycles, ethanol-treated animals had irregular estral cycle and persistent oestrous phase compared to controls and betaine-treated rats. In conclusion, these results demonstrate for the first time the antioxidant and methyl donor properties of betaine in the rat ovary. Thus, betaine might be used as a potential therapy in hyperhomocysteinemia and partial infertility mediated by oxidative stress in females.     

CO2 biofixation and fatty acid composition of two indigenous Dunaliella sp. isolates (ABRIINW-CH2 and ABRIINW-SH33) in response to extremely high CO2 levels

Bioprocess and Biosystems Engineering - Global warming, as a result of atmospheric CO2 increase, is regarded as an important universal concern. Microalgae are considered as appropriate...     

Compatibility and interaction between Bacillus thuringiensis and certain insecticides: perspective in management of Tuta absoluta (Lepidoptera: Gelechiidae)

Bacillus thuringiensis var. kurstaki (Berliner) (Bt) has been suggested as a biological control agent for Tuta absoluta (Meyrick). The objective of this study was to determine the interaction between abamectin, azadirachtin, indoxacarb, chlorantraniliprole, dichlorvos and metaflumizone with Bt. Effect of recommended doses of the chemical insecticides on colonisation of Bt was also investigated in culture medium. Except for metaflumizone, none of the chemicals tested reduced the colonisation of Bt compared with control. Interaction between Bt and the chemical insecticides on 2nd-instar larvae was also assessed. In interaction tests, Bt was applied at LC₅₀ level, 0, 12, 24 or 36 h after treating the larvae with LC₁₀ or LC₂₅ of the chemical insecticides. An antagonistic effect was observed in all treatments where Bt was applied immediately after the chemical insecticide. Also, antagonism was observed when treatment with Bt was done 12 h after azadirachtin and metaflumizone applications. Applying Bt 12 and 24 h after treatment with LC₂₅ of chlorantraniliprole, dichlorvos and abamectin resulted in synergism. But, synergism with LC₁₀ of dichlorvos and abamectin was observed only after 12 h. Additive effect was observed in the rest of the time and concentration combinations. Based on the results obtained, simultaneous use of the chemical insecticides tested and Bt is not recommended for T. absoluta control; and an appropriate time interval should be taken into consideration accordingly.