Crop Biotechnology
Year:2016 | Volume:6 | Issue:15|Papers Count:6

Soil salinity is one of the major abiotic stresses that dramatically reducing crop productivity in the world. Recent studies indicate that the application of exogenous salicylic acid (SA) as a key molecule in the signal transduction pathway participates in the signaling of abiotic stresses. The role of salicylic acid in salinity signalling is, however, unclear. In the present study, two barley (Hordeum vulgare L.) varieties (Reyhan and Nosrat) contrasting in their salinity tolerance were used to assess the role of various SA concentrations on the expression of Receptor-like kinases (RLKs) genes. The results demonstrated that that salinity and salicylic have a significant effect on seedling traits of barley cultivars. Salinity stress and salicylic acid increased the expression of Hv3ARK, IdiRLK2 genes in the cultivar Nosrat but in the other cultivar the relative expression of the genes were different. These results suggest the involvement of a number of RLKs in SA-mediated abiotic stress responses.

Desaturase enzymes (EC: 1.14.19.3) catalyze dehydrogenation reactions and creates a double bond in the fatty acid chains. These enzymes classified into two groups, soluble and membrane each with different consensus motifs. Despite the Delta-6 desaturase is a key enzyme in the biosynthesis of unsaturated fatty acids but due to lack of structural information of membrane-bound desaturase, it's three-dimensional and crystal structure has not been determined. Mortierella alpina is a rich source for production of unsaturated fatty acid arachidonic and has an active Delta-6 desaturases enzyme. The aim of this study was obtain encoding sequences of Delta-6 desaturase gene, and determination of functional domains using comparative analysis and molecular model and propose a membrane topology model for this enzyme. Thus, after extraction of total RNA and cDNA synthesis using gene specific primers, PCR product was cloned into pBlueScriptSK+ vector and then sequenced. Based on bioinformatics analysis by Swissmodel, Predict and Phobius servers presence of functional domains cytochrome b5 carrying motif (HPGG), three His-box motifs and transmembrane regions were identified. Then we proposed a membrane topology model for the Delta-6 desaturase enzyme.

Genetic diversity is the best way to use available genetic potential for breeding programs in barley. In this study, genetic diversity of 63 Iranian and non-Iranian genotypes have been described. 29 out of 30 pairs microsatellite markers were polymorphic. A total of 225 alleles for different gene loci with an average of 2.7 per locus were identified. The highest number of alleles for Bmag0323, Hvm54 and EBmac679 (with 13 alleles) and the lowest number for the HVM0003 (with two alleles), respectively. The PIC amount and Shannon index value were variable ranging from 0.89 (for the EBmac679) to 0.21 (for the GBM1176) and from I=2.46 (for the Bmag0323) to I=0.48 (for the GBM1176), respectively. Genotype clustering was done using Neighbor-net and Cluster analysis was performed using Bayesian methods. The best number of subpopulations was identified 4 that were seen in most sub-populations genotypes originating from Iran. The results of clustering of Neighbor-net method showed good agreement with the modelbased approach. The results showed that microsatellite markers well represented different genotypes of barley diversity. Also according to the results, native genotypes showed more diversity.

One of the plant resistant mechanisms to abiotic stresses is production of a compatible solute named glycine betaine. Choline is the precursor of this important metabolite and it is also essential compound for the structural integrity and signaling of cell membrane. In plants, the most important step of choline production is catalyzed by cytoplasmic phosphoethanolamine N-methyltransferase (PEAMT; EC 2.1.1.103) enzyme. In this study, PEAMT gene from spinach (Spinacia oleracea Iranian landrace) was amplified using specific primers and cloned into an intermediate cloning vector (pJET). In order to overexpression of PEAMT gene, the construct of PBI121GUS-9: PEAMT was made and finally was transferred to the Agrobacterium tumefaciens GV3101 (PMP90). Floral dip method was used for transformation and initial analysis of putative transgenic plants was tested in selective medium containing kanamycin. Then resistant seedlings at the molecular level were evaluated using PCR and RT-PCR methods. Results confirmed plant transformation in the level of transcription. Subsequently, The phenotypic analysis under salt stress showed that the main root length of transgenic plants was significantly longer than control nontransgenics. In adition, glycinebetaine contents and peroxidase activity were significantly higher in transgenic compare to non-transgenics control plants.

Drought is one of the major environmental stresses that greatly affects growth and development of plants. The plants reaction against this stress is associated with showing massive changes in complex gene networks. In the present study, the changes of gene expression patterns in two sensitive and tolerant genotypes of rice (as C3 plant) and maize (as C4 plant) were investigated using maize genome arrays containing 17,734 probe sets and the rice genome containing 57.381 probe set. The microarray data were taken from the GEO/NCBI database on both stress and control conditions to identify the genes involved in responses to the stress. The results indicated that 1861 (10.49%) and 1753 (8.9%) genes in the sensitive and tolerant maize, respectively, and 9252 (16%) and 7971 (13.8%) genes in the sensitive and tolerant rice, respectively, changed significantly after drought stress at the level of one percent. From of these genes, 1012 and 175 genes in the sensitive and tolerant genotype leaf of rice and maize, were significantly up-regulated, respectively. The Venn diagram showed that 663 genes of rice and 158 genes of maize, have significantly down-regulated. Rice plant, as a C3 plant, showed five times wider reaction to drought stress in compared with maize plant, as a C4 plant. The functional grouping of the up-regulated genes in two species revealed that functional group of ribosomal proteins and phosphatases in maize plant have the most abundant categories, whereas the functional groups of metal-binding, stress response, response to biological stimuli and signals in rice plant contained the highest percentage of the genes.

Cereal rusts are the most important wheat diseases in Iran and worldwide. One of the most effective control measures of these diseases is deployment of resistant cultivars. The objective of this study was identification of stem rust resistance genes and pyramiding these genes in wheat cultivars Bahar and Pishtaz. For this purpose, initially the virulence of eighteen isolates of stem rust that had been collected from several parts of Iran was studied in cultivars/lines Bahar, Pishtaz, Eagle, AC Cadillac and Tr129. Results showed that cultivars AC Cadillac, Eagle, and Tr129 with Sr42, Sr26 and SrTr6A genes had good levels of resistance to all evaluated isolates. In order to transfer resistance genes to Bahar and Pishtaz cultivars, after initial and complementary crosses the F1 seedling resulted were evaluated for their resistance to stem rust and consequently the progeny of complementary crosses were screened for presence or absence of resistance genes using molecular markers. For Sr26 gene, primers Sr26#43 and BE518379; for Sr42 gene, primer STS (FSD-RSA); and for SrTr6A gene, primers GPW2295 and GPW4032 that showed polymorphism between parents were used to detect presence or absence of resistance genes. Using the seedling test in green house and also detection of molecular markers, it was found that for progeny of complementary crosses in cultivar Bahar transfer of resistance genes Sr26, Sr42 and SrTr6A have been successfully completed, and in Pishtaz based on distinctive ability of markers used, at least transfer of two genes of three genes in progenies was proved.