فصلنامه ژنتیک نوین
سال پنجم شماره 4 (پیاپی 23، زمستان 1389)

Abiotic Stresses are one of the most important reasons of the reduction in crop production. As plants are sessile, changes in expression, accumulation and synthesis of proteins along with other cell metabolism modifications help for keeping their stability and establishment of acclimation. Dehydrin proteins (also known as group 2 late embryogenesis abundant (LEA) proteins) are produced in a large group of organisms and in different cell parts in response to low temperature and drought stresses. DHNs are characterized by three highly conserved domains known as the K, Y, and S segments. The number and order of the Y, S and K segments define different DHN subclasses: YnSKn, YnKn, SKn, Kn, and KnS and for everyone is suggested specific function. Although the exact function of dehydrins is still unclear, they function as cryoprotectants proteins, osmoregulators, radical scavengers, chaperones and roller in binding to membrane lipids and metals. Here, we summarize the types and roles of plant dehydrins in response to temperature stresses

Beta-lactaglobolin is the most cheese water protein in ruminant milk. The aim of the present study was to detect the polymorphism in exon and intron 4 region of beta-lactaglobolin gene in Holstein cattle. Blood samples randomly were collected from 48 Holstein cattle from Astan–e Ghods Razavi's farm and transported to the laboratory and stored at -20°c for further analysis. DNA was extracted using modified salting out method. Fragment of 434 base pairs from exon and intron 4 region of LGB gene was amplified by a specific primer pairs using polymerase chain reaction (PCR). The PCR products were digested by HaeIII restriction enzyme and electrophorsed on 12% poly-acryl amid gel. The enzyme digestion of PCR produce resulted A allele with 300, 113 and 21 bp and B allele with 226, 113, 74 and 21 bp for beta-lactoglobulin locus. Frequency of A and B alleles were estimated at 39 and 61%, respectively, and the frequency of AA, AB and BB genotypes was 22.91, 31.25 and 45.84%, respectively, with the of mean heterozygosis of 0.47

This study was carried out to determine quantitative differences and expression pattern of three candidate gene for resistance to Fusarium Head Blight in response to Deoxynevalenol (DON), the main mycotoxin product fo F. graminearum the causal agent of FHB. The results showed that 10 mg/l DON has not significant effect on germination of resistant and susceptible varieties of wheat. But 5-15 mg/l concentration of DON caused significant reduction in fresh and dry weight of resistant, semi resistante and susceptible plantlets. The effect of DON on quantitative expression of three resistance candidate genes including PDR5- NPR1- Xsts3B-138_1 was studied with Real time PCR. The increase in expression of PDR5 was significant after DON treatment in Falat (susceptible) and Frontana (semiresistant). NPR1 expression was reduced significantly after DON treatment in all varieties. Real-time quantitative PCR showed that the relative expression of Xsts3B-138_1 was reduced in Falat and Frontana after DON treatment but not in Wangshuibai

To study the relationship between four species of almond sub genus. The kariosystematic evolution in Amygdalus communis L.,A. Corduchorum Bornm, A. orientalis Duh, and A. eleaegnifolia Spach were done by the karyological methods. The root meristem cells was used for these studies. In each specimen, ten suitable metaphase plate were selected and photographed. The standard chromosome squash was prepared for the species and the population separately and the parameters of the chromosomes including the complete length of the chromosomes, the length of the long arm, the length of the short arm, the relative length of the arms (AR)and the relative length of the chromosomes etc were calculated. There was significant difference between all of the species that can be employed to distinguish the species. All of the studied species were diploid (2n=16). Avarage size of chromosomes in species of this genus was 2.23± 0.04 micrometer. Also according to the measured cytological characters, A.communis L. had the most similarity with the species of A. orientalis Duh and the species of A. Corduchorum Bornm and A. eleaegnifolia Spach had the most similarity with each other. In finally, studied species were classified two groups cytologically.

PEPCK-C gene codes the phosphoenolpytuvate carboxykinase enzyme which has a key role in gloconeogenesis. There are two different types of PEPCK gene: mitochondrial PEPCK (PEPCK-M) and Cytosolic PEPCK (PEOCK-C). In these study 100 random samples from two native populations Khazak and Dashtiari in Sistan and Bluchestan region, namely, Khazak and Dashtiari were analyzed. DNA was extracted from feather pulps and PCR was carried out using primers F1R1, F2R2, F3R3 and F4R4 which amplifies 800 bp, 1000 bp, 1000 bp and 1080 bp fragments from the chicken PEPCK-C gene. The fragment covers from promoter to exon 3 of the PEPCK-C gene. PCR products were then digested by 2 restriction enzymes BstE Π and Aci I. Allelic as well as genotypic frequencies for two populations were determined and analyzed by Popgene software. Haplotype analysis in two population showed that there were three haplotypes B, C and D and their frequencies were 0., 0.84 and 0.02 for Khazak chickens and 0.02, 0.90 and 0.08 for Dashtiari chickens, respectively.

In the present study, drought-induced changes in some antioxidant enzyme activities (catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and superoxide dismutase (SOD)), total soluble protein content, chlorophyll, proline and glycine betaine were investigated in two barley (Hordeum vulgare L.) cultivars differed in drought tolerance condition, namely Kavir (toleran) and Jonub (sensitive) with or without silicon. A factorial experiment was performed in a completely randomized design with three replications for three treatments (Control, Drought, Drought silicon). According to variance analysis, all simple and contrast factors effect were significantly meaningful except treatment × cultivar contrast effect of peroxidase. The results show that application of silicon was induced to increase antioxidant enzymes activities and osmolytes in both cultivars under drought stress condition. The contents of chlorophyll and total soluble protein were significantly decreased by drought on both cultivars, whereas application of silicon approximately compensated such decrease. Generally, all studied activities of treatments were higher in the tolerant cultivar than the sensitive. It might be concluded that silicon is caused to increase antioxidant enzyme activities to elevate drought tolerance in both cultivars. Therefore, silicon may be involved in metabolic or physiological activities in higher plants under stress.

In the process of acclimation, plants show tolerance to low temperature inception by gene activity and cell metabolisms regulation. In this study quantification of Beta galactosidase and Beta glucosidase as genes involved in responses to temperature stresses alongside electrolyte leakage as a cell membrane damage indicator were evaluated in several intervals under cold and freezing stresses in Kabuli and Desi types of chickpea plants. Results indicated differences in the pattern of genes expression in both genotypes. Reduced expression of both studied genes in Jam genotype and unstable changes of genes in 4322 genotype at acclimation temperature indicated that response pattern of these two genes to this condition is down regulation that coincided with less membrane damage of jam genotype. Transfer of acclimated seedlings to freezing temperatures was accompanied by strong increases in electrolyte leakage index in 4322 and no changes in Jam. These alterations showed the relationship between the expression of these genes with responses of Jam genotype to cold stress and lack of acclimation mechanisms in 432. Generally this study showed that more down regulation of Beta galactosidase and Beta glucosidase genes which was parallel with more stable expression of these genes and less membrane damage, in Jam genotype than 4322 in response to short cold acclimation, could be regarded as one of the mechanisms involving in cold tolerance.

The purpose of this study was investigation correlation peroxidase alleles and Simple Sequences Repeats (SSRs) in tissue culture of Eucalyptus microtheca. To this aim, the green twigs of 1- year-old E. microtheca seedling separated and were cultured on modified MS medium (without half-strength KNO3 and NH4NO3) with different levels of hormones α-Naphthalene Acetic Acid (NAA), Kinetin (Kin) and TDZ. As a biochemical marker, the patterns of peroxidase bands were studied in PAGE method. A dimer gene location, a tetramer locus and two epigenetic bands were observed. The genome variations were investigated using SSR molecular marker and used primers shown several polymorphisms on somaclonal plantlets. Nonparametric statistical analysis confirmed SSRs significant effects on the peroxidase alleles. But the correlation two similarity matrix was 0.18 by Mental test.

Bread wheat (Triticum aestivum), with the highest planting area and production in Iran, is encountered with drought as one of the major environmental factor reducing grain yield. Genetic diversity of wheat cultivars is very important in reducing genetic vulnerability during plant breeding efforts. In order to estimate the genetic diversity, molecular markers provide excellent tools. Inter simple sequence repeat (ISSR) markers were used to evaluate genetic variability among 26 bread wheat cultivars (15 tolerant and 11 susceptible). A total of 10 out of 21 tested ISSR primers produced polymorphic scorable banding patterns and were used to amplify wheat genomic DNA. One hundred and thirty three loci were scored, of which ninety two were polymorphic (0.92). The mean polymorphism information content (PIC) value was 0.37. The primers K13 and UBC 840 had the highest PIC value (0.40). Based on Jaccard’s similarity coefficients, the most genetic distances was between cultivars venak (resistant) and marvdasht (susceptible) while genetic distance between omid (resistant) and backcross- roshan (resistant) was the least. Dendrogram produced from minimum ward-based cluster analysis divided studied cultivars into two main groups. Results of the current study demonstrated that ISSR markers could be efficiently used to evaluate wheat genetic diversity.

alinity is one of the most important abiotic stresses which deduced crop yields annually around the world, especially Iran. Most of the crop plants are susceptible to salinity and can not survive under very acute salinity, if survive they have very low products. Based on different studies, several genes with different function are induced in response to salinity and several transcription factors involved in regulation the expression of these genes. In this study, the expression pattern of two genes which their product is essential transcription factors for expression of salinity tolerance genes, were investigated using QRT-PCR. Sampling was done from 8-days seedling of tolerant and susceptible wheat varieties which were grown in -0.25, -0.5, -0.75, -1, -1.25 and -1.5 MPa of salinity treatment induced by NaCl as well as distilled water treatment as control and the expression pattern of TaDBP and TaDREB2 genes were studied. These genes belong to AP2/EREBPs transcription factor family. Results showed that, TaDBP was up-regulated in tolerant variety (Kavir) which means the product of this gene can act as a transcription factor to induce the promoter and transcription of salinity tolerance genes. In contrast, the expression pattern of TaDREB2 gene showed that this gene can be as a repressor transcription factor in expression of genes involved in salinity tolerance in studied variety.