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Plant growth is greatly influenced by environmental stresses including water deficit, salinity and extreme temperatures. Therefore, the identification of genes, especially regulatory ones whose expression enables plants to adapt to or to tolerate these abiotic stresses, is very essential. MYB proteins, a superfamily of transcription factors, play regulatory roles in developmental processes and in defense responses in plants. Members are characterized by a structurally conserved DNA-binding domain, i.e., the MYB domain. Thus, a factorial experiment in a randomized complete block design with three replications was carried out to investigate the effect of different levels of drought stress on the relative expression of TaMYB73 transcription factor gene using Real Time PCR method at Biotechnology Research Institute of Zabol University. The experimental treatments included durum wheat genotypes (Shabrang, Behrang, Karkheh, Aria and Dena) and drought levels (5, 10, 15, 20 and 25% of field capacity). Seedlings of genotypes
were cultured in pots and drought stress was exerted after 45 days (four to five leaves). Data analysis was performed using Ratio =2 ^-ΔΔCT and SAS software version 9.1. The results of the 2-way ANOVA for the effect of genotype, drought stress and cross-effects of drought stress on the relative expression of TaMYB73 gene and the amount of osmotic regulators (Proline and Carbohydrate) at different stress levels (20, 15, and 5% of field capacity) were significant in comparison with the normal condition (25% of field capacity) at 1% probability level. With the increase of drought stress level from 5 to 20% of crop capacity, relative to the normal level (25% crop capacity), the relative expression of TaMYB73 gene and osmotic regulators of proline and carbohydrates increased in Beharang, Karkheh and Dena genotypes. Therefore, Karkheh and Dena genotypes showed greater resistance to drought stress among the 5 genotypes studied.
 

 

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Polyploidy induction in German chamomile (Matricaria chamomilla L.) by herbicide trifluralin
 
Leila Karami¹, Mohammad Modarresi², Mohammad Amin Kohanmoo², Fatemeh Zahabi Ahmadi² & Saeed Irian^3
1Department of Horticulture, Faculty of Agriculture and Natural Resources, Persian Gulf University, Bushehr, 7516913817, Iran; ²Department of Plant Breeding, Faculty of Agriculture and Natural Resources, Persian Gulf University, Bushehr, 7516913817, Iran; ³Department of Cell and Molecular Biology, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran.
Correspondent author: Leila Karami, leila.karami@pgu.ac.ir
 
Abstract. Chamomile (Matricaria chamomilla L.) is a medicinal herb belonging to Asteraceae family. This study was conducted to investigate the effect of trifluralin on the induction of polyploidy in chamomile. Two independent full factorial experiments on seedlings and 2-leaf stage apical buds were performed.  Following morphological, biochemical and cytogenetic analysis, chromosome numbers of 18 and 36 were detected for diploid and tetraploid types, respectively. Morphological and biochemical examinations revealed that an increase in the number of full chromosome set results in a reduction in stomata number per unit area as well as an increase in stomata size, chloroplast number, and chlorophyll content. Induction of ploidy level increments also reduced plant height and increased the number of lateral branches, leaf size, and diameters of stems, flowers and receptacles. It is concluded that a concentration of 22.5 µM trifluralin in both methods is optimum for the production of tetraploid chamomile with the highest rate of polyploidy induction and the lowest percentage of abnormality.
 
 

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Yersinia pestis, a gram-negative rod belonging to the Enterobacteriaceae family, is the causative agent of plague. Classical methods of detecting the organisms are time-consuming, expensive and dangerous. The aim of the study was to design a Real-time PCR assay on the basis of the pla gene of Yersinia pestis. In this research the Real- time PCR test was optimized by using special primers for targeting pla gene. After preparing 10-fold serial dilutions of the pla and their analysis by the assay, the last dilution showing a fluorescent signal was confirmed as the limit of detection (LOD). A standard curve based on the Ct values was depicted, so the assay was developed to quantify the target gene. The analytical specificity was determined by subjecting the genome of some control negative bacteria to the assay. In this experiment, negative control genomes did not show detectable signals in the assay. The last dilution of pla plasmid which showed a fluorescent signal was 4.5 fg. So, the lower detectable copy numbers of the gene in a 20 μl PCR reaction was calculated as 1×10³.
 

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Pancreatic cancer is one of the most deadly and aggressive cancers; Fluorouracil induces apoptosis and cell cycle arrest in cancer cells. In the present study; the effect of Fluorouracil on different stages of the cell cycle and the expression of genes involved in the internal pathway of apoptosis in the AsPC-1 cell line (human pancreatic cancer) were investigated. In order to do so, MTT assay was used to evaluate the cytotoxic effect of Fluorouracil on AsPC-1 cell proliferation; The type of induced cell death and cell cycle changes were investigated by flow cytometry; changes in the expression level of genes (BAX, Bcl-2, APAF-1, Caspase-3, Caspase-9, p53, p21) were examined by Real-time PCR. Quantitative data were analyzed at the significant level of (p<0.05). The MTT assay results showed that Fluorouracil decreased AsPC-1 cell proliferation in a concentration-dependent manner. The results of flow cytometry analysis showed that increased percentage of apoptotic cells in the treated cells; Fluorouracil induces S phase cell cycle arrest in AsPC-1 cells and reduced distribution in the G1 phase. The Real-time PCR results in treated cells showed an increase in the expression of genes in the mitochondrial apoptotic pathway as well as genes effective in regulating the cell cycle. Fluorouracil reduces cell proliferation and induces apoptosis by increasing the expression of genes involved in the Intrinsic apoptotic pathway in AsPC-1 cells; Fluorouracil also caused cell cycle arrest in these cells by regulating the (p53, p21) genes.