مجله زیست فناوری گیاهان زراعی
پیاپی 17 (بهار 1396)

This study aimed to investigate the effect of drought stress and silver nanoparticles on beta-carotene hydroxylase (bch) gene expression and carotenoid production in saffron. The experiment was implemented in two levels including normal irrigation and full drought stress on nine ecotypes of saffron in three levels: control (distilled water), 55 and 110 ppm of silver nanoparticles levels. This study was conducted in split plot factorial experiment based on randomized complete block design with two replications at research field of Birjand University and biotechnology institute of Zabol University.In order to examine gene expression pattern, after taking leaf samples from all treatments, RNA extraction, cDNA synthesis and determination of temperature gradient, Real time polymerase chain reaction (Real-Time PCR) was used. Then, Data were analyzed using EX and SAS 9.2 software. The main effects of treatments with nine ecotypes of saffron, silver nanoparticle and drought stress and their interaction effects for bch gene expression and amount of carotenoid were significant at 1% probability level. The maximum bch gene expression and the amount of carotenoid was observed in 55 ppm of silver nanoparticles under drought stress in Ghaen ecotype (1478.62 & 21.37 µg.g-1, respectively). Therefore, drought stress and silver Nanoparticles up to 55ppm increased bch gene expression and carotenoid production.

The biosynthesis pathway of fatty acids is one of the important pathways in the body of most organisms that an enzyme Acyl carrier protein (ACP) plays an important role in it. The purpose of this study is phylogenetic and in silico analysis of gene ACP. More analysis indicate that ACP gene has 4 exons, 3 introns and and 2 mRNA in prokaryotes and 13 exons, 12 introns and 9 mRNA in eukaryotes. This protein has target mitochondrial in plant eukaryotes and non-mitochondrial target in prokaryotes and it is not also included of secreted proteins. The results of multiple alignments by T-Coffee server showed that the ACP genes between bacterial species are more protected than plant species. Phylogenetic analysis of ACP proteins in prokaryotes is revealed that except for a cluster, in other case Gram-positive bacteria are in one cluster and gram-negative bacteria are in another cluster. In eukaryotes, different plant species are scattered in different clusters. These results indicated that clustering in eukaryotes are not relate to species. In addition, the study of ACP proteins in eukaryotes and prokaryotes revealed that both eukaryotes and prokaryotes are placed together in some clusters that is due to the similarities of sequences in species. Comparison of the secondary structure of the protein in eukaryotes and prokaryotes showed that the number of alpha and beta sheets in prokaryotes are more than of eukaryotes. Three-dimensional modeling of this protein was done by homology modeling using Swiss Model database in wheat (as representative of eukaryotic) and bacteria Clostridioides difficile 630 (as represented prokaryotes). The best templates were extracted with high similarity from PDB database. To validation of modeled structure and esterochemical analysis, Ramachandran plot was drawn and dihydral angles were calculated. Structural quality evaluation results showed that the proposed models are good quality and stability. The study of protein structure may help to understand protein function and the details of its structure can be useful in studies of the active site of the protein and docking.

Drought is one of the most devastating environmental stresses that adversely affect plant metabolic processes. Many plant genes such as photorespiration ones are involve in response to drought stress. In the present study, the effects of drought stress on the expression level of two peroxisomal (Hydroxy pyruvate reductase (HPR1) and Glycolate oxidase (GO)) and two mitochondrial (Serine hydroxy methyl transferase (SHMT) and Glycine decarboxylase (GDC)) genes were studied in susceptible (Hayola308) and tolerant (SLM046) genotypes of canola (Brassica napus) under stress (irrigation cut at flowering stage) and non-stress conditions. The result of real time-PCR showed that in Hyola308 genotype the expression level of GO gene at 48, 72 and 96 hours after stress was higher than SLM046 genotype. In Hyola308 genotype, the highest expression level of GDC gene observed at 48 hours of stress and then decreased. The highest relative expression level of SHMT gene in both Hyola308 and SLM046 genotypes detected at 24 hours after stress and then in SLM046 genotype, its level decreased at 48 hours after stress, while in Hyola308 genotype, its expression declined over the time of exposure to stress. SLM046 genotype showed highest amount of HPR1 expression level at 48 hours after stress. It seems that the expression of photorespiration genes in SLM046 genotype increased at the initial times of exposure to stress and with continue the stress, it showed more adaptation to stress and control the photorespiration unlike Hyola308.

This study was carried out to evaluate the effect of salicylic acid on the reduction of disease severity of septoria tritici blotch (STB) in three tetraploeid and three hexaploeid wheat cultivars, under controlled conditions at seedling stage. The 10-day-old seedlings were initially treated with 0 (control), 1, 2 and 4 mM of salicylic acid with a handy sprayer. After 24 hrs, the seedlings were inoculated with fungal spore suspensions adjusted at 107 sopres/ml. The disease progress was evaluated 21 days post inoculation based on visual estimation of the percentage of leaf area with necrotic lesions bearing pycnidia. The results showed that there were significant differences on the reduction of disease severity among different concentrations of applied salicylic acid as well as among cultivar/ concentration interactions. In addition, the results showed that application of salicylic acid reduced disease severity of both tetraploid and hexaploid wheat cultivars and 1 mM salicylic acid was the most effective concentration on the reduction of disease severity. Although, the disease severity was significantly reduced by application of 2 and 4 mM salicylic acid, the effectiveness of these concentrations was less than application of 1mM. Overall, these results revealed that activation of plant defense systems through application of salicylic acid could play a significant role in systemic acquired resistance against STB disease.

Environmental conditions lead to biosynthesis of signaling molecules including phytohormones in plants which have important functions as primary messengers in signal transduction and regulating cell metabolism. Jasmonic acid hormone by controlling the transcription factors can play key roles in response to various stresses and developmental processes in plants. Despite numerous studies, plant responses to the hormone are not completely understood. Here, microarray data of Arabidopsis from GEO database was used for analysis of co-expression network. WGCNA (Weighted Gene Co-expression Network Analysis) analysis determines 25 gene groups (modules) that their expression profiles correlated highly significant with each other in response to jasmonic acid. Gene ontology was utilized to investigate each module for statistical significance. This analysis indicated that jasmonic acid controls many processes including photosynthesis, cell programmed death, and response to various stresses. In addition, many of transcription factors such as 11 genes of NAC family and 12 genes of bHLH family play roles in the regulation of jasmonic acid responses and adjust processes including response to biotic and abiotic stresses, flower development and response to light.

Water deficit is the most important abiotic stress limiting crop productivity in most arid and semi-arid areas of the world and Iran. In order to achieve precise experimental comparisons, the response of chickpea genotypes MCC508 and MCC 521 to water deficit was evaluated and then expression of the genes assessed under the same stress situation. Decreasing trend of Relative Water Content (RWC) was significantly less in MCC508 compared with MCC521, especially after 24 hours (p≤0.05). Membrane Stability Index (MSI) was also higher in MCC508 whereas electrolyte leakage and Malondialdehyde (MDA) accumulation were almost stable but increased 1.2-fold relative to control after four days stress. Proline was accumulated up to 16.8 and 9.4 µ mol g-1FW in MCC508 and MCC521 after 4 days, which indicated an increase of 5.1 and 3.8 fold related to the control, respectively. Semi-quantification gene expression analysis for Dehydrin1and CapLEA-1 showed different response to water deficit for each genotype. Both of these genes up-regulated in tolerant genotype MCC508 with the amount of 4 and 2.1 fold compared to their respective control (p≤0.05) so that the up-regulation trend steadily continued under the stress situation. However, CapLEA-1 expression was not significantly regulated in the sensetive genotype; instead, Dehydrin1regulation was significantly evident as much as 1.4 fold increase and then decreased (p≤0.05). It, therefore, seems that stable, high up-regulation of Dehydrin1and CapLEA-1 genes and their function (stability of lipids and cell memebrane, correct protein folding and detoxificaton) might be a possible reason for high tolerancy response to water deficit in MCC508 compared to MCC521.