miRNAs and Their Target Genes Play a Critical Role in Response to Heat Stress in Cynodon dactylon (L.) Pers.

Annual global temperature is increasing rapidly. Therefore, in the near future, plants will be exposed to severe heat stress. However, the potential of microRNAs-mediated molecular mechanism for modulating the expression of their target genes is unclear. To investigate the changes of miRNAs in thermo-tolerant plants, in this study, we first investigated the impact of four high temperature regimes including 35/30 °C, 40/35 °C, 45/40 °C, and 50/45 °C in a day/night cycle for 21 days on the physiological traits (total chlorophyll, relative water content and electrolyte leakage and total soluble protein), antioxidant enzymes activities (superoxide dismutase, ascorbic peroxidase, catalase and peroxidase), and osmolytes (total soluble carbohydrates and starch) in two bermudagrass accessions named Malayer and Gorgan. The results showed that more chlorophyll and the relative water content, lower ion leakage, more efficient protein and carbon metabolism and activation of defense proteins (such as antioxidant enzymes) in Gorgan accession, led to better maintained plant growth and activity during heat stress. In the next stage, to investigate the role of miRNAs and their target genes in response to heat stress in a thermo-tolerant plant, the impact of severe heat stress (45/40 °C) was evaluated on the expression of three miRNAs (miRNA159a, miRNA160a and miRNA164f) and their target genes (GAMYB, ARF17 and NAC1, respectively). All measurements were performed in leaves and roots simultaneously. Heat stress significantly induced the expression of three miRNAs in leaves of two accession, while having different effects on the expression of these miRNAs in roots. The results showed that a decrease in the expression of the transcription factor ARF17, no change in the expression of the transcription factor NAC1, and an increase in the expression of the transcription factor GAMYB in leaf and root tissues of Gorgan accession led to improved heat tolerance in it. These results also showed that the effect of miRNAs on the modulating expression of target mRNAs in leaves and roots is different under heat stress, and miRNAs and mRNAs show spatiotemporal expression. Therefore, the simultaneous analysis of miRNAs and mRNAs expressions in shoot and roots is needed to comprehensively understand miRNAs regulatory function under heat stress.

Screening of Amaryllidaceae alkaloids in bulbs and tissue cultures of Narcissus papyraceus and four varieties of N. tazetta.

Narcissus spp. are an economically important crop for medicines in relation with the alkaloids production, mainly galanthamine, an acetylcholinesterase inhibitor used for the treatment of Alzheimer's disease. In this article an extensively study of the phytochemistry of both bulbs of different species and varieties of Narcissus grown in Iran and in vitro culture of these plants was investigated. In particular, the Amaryllidaceae alkaloid profile and the galanthamine and lycorine contents in wild bulbs of Narcissus papyraceus (G5) and four varieties of Narcissus tazetta (N. tazetta var. Shahla (G4), N. tazetta var. Shastpar (G1), N. tazetta var. Meskin (G2), N. tazetta var. Panjehgorbei (G3)), growing in Iran are reported. The alkaloid profiles were investigated by GC-MS and LC-MS and the quantitative analysis was performed using GC-MS. In total, thirty alkaloids were identified among them nine alkaloids were observed with the both methods of analysis. The variety Meskin of N. tazetta (G2), showed the highest diversity of alkaloids and the highest content in galanthamine. On this last species (G2) and on N. tazetta var. Shahla (G4), the effects of auxins 2,4-dichlorophenoxyacetic acid (2,4-D), 4-amino-3,5,6-trichloropicolinic acid (Picloram) and naphthalene acetic acid (NAA) at concentrations of 25 and 50 µM were studied on the induction of callus and its capacity to induce organogenesis and alkaloid diversity. All auxins, at the concentrations of 25 and 50 µM, produced calli. Bulblets and roots were formed on calli grown only in the presence of 25 or 50 µM NAA. GC-MS analyses showed the presence of galanthamine and lycorine in calli, roots and bulblets, with all auxins whatever the concentration used while demethylmaritidine and tazettine were found in differentiated tissue cultures cultivated on the medium containing NAA (25 or 50 µM) or in calli initiated with Picloram (50 µM). Precursor 4'-O-methylnorbelladine (MN) of Amaryllidaceae alkaloids feeding was found to significantly improve the accumulation of both galanthamine (82 µg/g DW) and lycorine (1800 µg/g DW) in bulblets of N. tazetta var. Meskin (G2).

Comparison between antibiotic therapy of Brucellosis with and without vitamin A.

BACKGROUND: Brucellosis is one of the endemic diseases in our country and it can be in the types of acute, sub-acute or chronic. It estimates that about 20% of Brucellosis may change from acute to chronic. Because cell mediated immunity (CMI) is the main defense of body against Brucella species, it seems that some degree of Immunologic disorders existed in the patients with chronic form of diseases and some supplements such as Vitamin A (Vit A) as an immunomodulator can stimulate CMI and may decrease the rate of chronicity. MATERIALS AND METHODS: In a single-blind randomized clinical trial 120 patients with the clinical and serological diagnosed Brucellosis were randomized. A total of 60 patients received streptomycin and Doxycycline as standard therapy for 6 weeks and others in addition to this Regimen received Vit A for about 4 weeks. RESULTS: In the case group, only 1 case (1.6%) relapsed and in the control group 8 (13.5%) with significant difference (P < 0.005) between two groups. Morbidity of disease was different between two groups. CONCLUSION: Vit A therapy in the patients with Brucellosis with may reduce the disease morbidity and rate of chronicity.

Effects of temperature and photoperiod on postponing bermudagrass (Cynodon dactylon [L.] Pers.) turf dormancy.

Growth chamber and field experiments were carried out to determine the effects of extended photoperiod under low and freezing temperatures on bermudagrass turf dormancy at Bajgah, in the southern part of Iran. The experiment in the growth chamber was conducted with four temperature regimes (15, 7.5, 0 and -7.5°C) and three light durations (8, 12 and 16h) in a completely randomized design with four replications. The field study was conducted in two consecutive years (2008-2009) with three light durations (8, 12 and 16h) in months with natural short day length and arranged in a randomized complete blocks design with three replications. Results in both experiments showed that decreasing temperature and photoperiod decreased verdure fresh and dry weight, shoot height, tiller density, leaf area and chlorophyll and relative water contents (RWC). However, rooting depth and fresh weight of roots increased in the growth chamber. Decreasing the temperature and light duration increased electrolyte leakage and proline content. Reducing sugars increased with decreasing temperature and declined with lowering light duration in both shoots and roots. Starch content of both shoots and roots showed an adverse trend compared to reducing sugars; starch content increased in both shoots and roots in all treatments by shortening the photoperiod. Practically, the problem of bermudagrass turf's dormancy could be solved via increasing the photoperiod in months with short day lengths. This treatment would be efficient and useful for turfgrass managers to apply in landscapes and stadiums.