جستجوی مقالات مرتبط با کلیدواژه "پروتئین های شوک حرارتی" در نشریات گروه "زراعت"

Drought stress is one of the most important environmental factors, which limit the growth of plants. By the end of the 21st century, the incidence of drought stress is expected to increase because of the global warming phenomenon. As a consequence, trees growth and viability in the forests and urban greenspace will reduce. Thus, selection of plants that are more tolerant to severe drought stress and are able to cope with such environmental conditions needs to be considered in future silvicultural strategies. This study was carried out to identify candidate drought-tolerance proteins in Maclura pomifera. Therefore, we aimed to explore the performance of Maclura pomifera under a severe drought stress and analyse the proteome changes of Maclura pomifera leaf in response to drought.

The experiment was carried out on 4-year-old Maclura pomifera saplings genotypes cultivated on a flat field in the Botanical Garden of University of Tehran. Saplings were exposed to irrigation regimes of 100% and 25% field capacity in a completely randomized design. Leaf samples were collected and were frozen immediately in liquid nitrogen and then stored at −80◦C to be used for further analyses. Experiments were performed using the gradient pH 3-10 NL IPG strips for the isoelectric focusing. IEF was carried out using the PROTEAN IEF. Strips were then equilibrated first for 15 min in reducing solution and then 15 min in alkylating solution. Equilibrated IPG strips were then placed and fixed using hot agarose on the top of home-made 12 % SDS- polyacrylamide gels. Separation of proteins in the second dimension was carried out in Protean XL cell. The protein spots were visualized by staining with BioSafe Coomassie gel stains following manufacturer’s instructions.

After doing two-dimensional gel electrophoresis, 25 protein spots that had displayed significant protein level changes were identified. Differentially expressed, proteins were divided in three groups. The first group included stress and defense proteins such as lipoxygenase, two types of heat shock protein, Allergen, Convicilin and legumin A2 precursorm; the second group included oxidative stress proteins such as Catalase, Chloroplast stromal ascorbate Peroxidase, Cytosolic ascorbate peroxidase, Iron superoxide dismutase and Manganese superoxide dismutase. Thethird group included energy and metabolism proteins such as Ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit, Ribulose -1,5- bisphosphate carboxylase /oxygenase small subuni, Translation elongation factor, Aldolase, Hydroxy-acid oxidase, Isopentenyl diphosphate isomerase, Dihydrolipoamide dehydrogenase and glyoxalase. The present results indicate that most proteins have been identified and their changes caused an increase in tolerance and adaptation of Maclura pomifera to drought stress. Also, our data suggest that drought tolerance of M. pomifera might be correlated with diminishing oxidative damage by activation of the antioxidant systems.

The present results indicate that most proteins have been identified and their changes caused an increase in tolerance and adaptation of Maclura pomifera to drought stress. Also, our data suggest that drought tolerance of M. pomifera might be correlated with diminishing oxidative damage by activation of the antioxidant systems.

Heat shock proteins (HSPs) are one of the main stress-responsive genes in plants that highly express in response to variable environmental stresses. Expression of HSP genes is primarily regulated by attaching heat shock transcription factors (HSFs) to binding sites at their promoter region. HSFs and their coding genes have been widely characterized in several plant species, but so far no report is available on the structure, organization, phylogenetic relationships and expression profile of these genes in halophyte species. Identification and characterization of gene family members properties in stress tolerant plant can be useful to understanding their molecular function and biological processes. The present study aimed to identify the HSF transcription factor gene families in halophyte plant Aeluropus littoralis.

The protein sequences of Arabidopsis thaliana HSF gene families were blasted against Aeluropus littoralis genomic sequences by local TblastN tools. After removing repetitive sequences, all sequences were verified by BlastP. In order to identification, annotation and analysis of domain architectures, the identified proteins were analyzed in different protein domain databases including Pfam 32.0, PROSITE and InterProScan. Similarity clustering based on motifs patterns were done by SALAD tool in all AlHSFs. The structure of exon and intron was generated by comparing the predicted CDS against genomic sequences of AlHSFs in gene structure display server (GSDS). The expression pattern analysis of AlHSFs genes was carried in leaf and root tissues under salinity stress and recovery conditions by transcriptome analysis.

In total, 11 non-redundant HSF genes encoding HSF domain-containing proteins were identified in A. littoralis genomes. Aeluropus HSF genes were named based on their identity to Arabidopsis AtHSF homologous proteins. All 11 AlHSFs were divided into three classes (A, B, and C), based on homology with Arabidopsis. Seven genes belonging to the HSFA class and three genes belonging to the HSFB class, and finally HSFC class like Arabidopsis had one gene. The gene structure analysis showed that AlHSF gene family member had distinct gene features, such as the composition and position of exons, introns, and conserved elements. The most AlHSF genes had two exons and one intron, while two genes (AlHSFA6B.1 and AlHSFA1B) contained three exons and two introns. AlHSFA6B.3 had six exons and five introns while AlHSFA6B.2 with one exon was intronless. Based on SALAd tool, 13 conserved motifs were identified from 11 AlHSFs. Motifs of 1, 2, 3, 4 and 5 were presented in most AlHSF proteins, except for AlHSFA6B.2 which lacked the motif 4 and 5. Motif 2 was also absent only in AlHSFA6B.2 and AlHSFB4. Removal of these motifs may have occurred during gene duplication in the evolutionary process of this family, resulting in shorter coding regions. Also, the results revealed that some motifs were present in specific AlHSF proteins. For example, motif 10 only existed in AlHSFA6B.1 and AlHSFB1. Motif 12 was only present in AlHSFA6B.1 and AlHSFA1B. The phylogenetic tree divided the proteins into three groups based on the existence and distribution of different motifs. The expression pattern of AlHSFs genes in leaf and root tissues under salinity and recovery conditions showed that AlHSFA6B.3 gene was not expressed, indicating that this gene was silent in these tissues under corresponding stress. AlHSFB2A gene had the highest expression level (1.11) in leaf tissue under salinity stress. After that, AlHSFA6B.1 gene with expression levels of 0.96 and 0.87 was expressed more in leaf tissue under salinity stress and recovery, respectively. The least expression level was observed in AlHSFC1 and AlHSFA3 genes, respectively, which was four times less than the control. AlHSFC1 gene showed a significant expression decrease in the recovery conditions after a little expression increase in leaf tissue under salinity stress. Significant expression decrease of AlHSFA3 gene was observed in root tissue under salinity stress which indicates its role as a negative regulator in response to salt stress.

Different expression patterns of AlHSF family member suggest distinct modes of positive and negative gene expression regulation. These may also be related to their different molecular functions as well as diverse regulatory mechanisms involved in controlling the activation of these genes. The findings of this study reveal the functional characteristics of the AlHSF genes and provide a foundation for future functional research regarding their biological roles in plant tolerance to stress.

In order to investigate the effects of seed aging and application of polyamines on the germination indices, gene expression and antioxidant enzymes activity in barley, a factorial experiment conducted based on completely randomized design with three replications. Treatments consisted of three aging levels (0, 11 and 14 days) and polyamines (putrescine and spermine). Germination indices, activity of antioxidant enzymes and expression of some genes were studied. Results showed that aging decreased germination percentage (GP) about 24 % in comparison to the control, but putrescine application increased GP about 18%. Germination rate (GR) decreased in the seeds aged for 14 days about 36 % and spermine increased GR about 87.5 %. Plumule and radicle dry weight increased 2 and 3 folds, respectively in putrescine and non-aged treatment rather than control. The highest activity of ascorbate peroxidase, peroxidase, polyphenol oxidase and superoxide dismutase (SOD) observed in the seeds aged over 14 days with putrescine application. Relative expression of genes encoding SOD and glutathione transferase was 8 and 22 folds greater, respectively in putrescine applied seeds aged for 14 days over control. Relative expression rate for HSP90 and PR10 genes was 5 and 8 folds greater than control, respectively in the same treatment. In conclusion, putrescine application invigorated the weak barley seeds and it can be related to improving the oxidative state of cells, greater protein conservation by high activity of HSP90 and increasing in the endogenous levels of seed hormones. Further in depth studies require to prove the role of hormones in seed vigor.