Crop Biotechnology
Year:2016 | Volume:5 | Issue:13|Papers Count:6

Induced resistance is one the ways by which plants cope with the biotic stresses. Pathogenesis-related proteins (PRs), including chitinase and b-1, 3-glucanase are synthesized by plant in response to pathogenic infection. In present work, we have carried out inoculation experiment in wheat to investigate the effect of salicylic acid (SA) and Pseudomonas flourescens on Septoria tritici Bloch (STB) symptoms. Subsequently, the expression profiles of chitinase and b-1, 3-glucanase were analyzed with semi-quantitative RT-PCR at 0, 4, 14 and 24 days after inoculation in both treated and control plants. Results showed that the expression of both chitinase and b-1, 3-glucanase genes increased in interaction with Z. tritici and the application of SA and P. flourescens. On the other hand, the application together had no significant effect on gene expression. Briefly, it can be concluded that increment of chitinase and β-1, 3-glucanase expression level with the application of SA and P. flourescens would play role induction of plant defense against STB.

The effect of some factors on embryogenesis from isolated microspore and plantlet regeneration from microspore-derived embryos was studied separately in Brassica napus. Experiments carried out in factorial based on completely randomized design. The first factor in all of the experiments was cultivars contained Global, Option and PF7045.91. The microspores were isolated from 3-4 mm buds and cultured on NLN-13 medium. Cultures incubated at 30oC and darkness for 14 days, and then transferred to shaker in the growth chamber at 25oC. In regeneration experiment, embryos with 20-25 days old were transferred to B5 medium and nearly 20-25 days after transferring embryos, normal regenerated plantlets, abnormal regenerated plantlets, rooted embryos and non differentiated embryos were counted. In the first embryogenesis experiments, the effects of medium volume, cultivar and interaction effects of two factors were significant. In Global cultivar, the highest values of embryos (695.5 per Petri) were observed in 12.5 ml medium volume. In the second embryogenesis experiment, the interaction between activated charcoal and cultivar on embryogenesis was significant. In the third embryogenesis experiment, the form of carbohydrate had a significant effect on embryo yield. In the first experiment of plantlet regeneration, GA3 had significant effect on normal regenerated plantlets, abnormal regenerated plantlets, rooted embryos and non differentiated embryos and the interaction between GA3 and cultivar was significant for normal regenerated plantlets. In the second experiment of plantlet regeneration, the interaction between gelling agent and cultivar was significant on normal regenerated plantlets.

Deciphering of network correlation operating in the plant biomass accumulation and yield production is a pre-requisite for understanding the relationships between omics data and growth rate in plants. To investigate the relationship among transcripts and their regulation for lignocellulose biomass formation at the generative stage of barley, transcript profiling was applied on three contrasting spring barley lines two weeks after flowering. A custom barley cDNA Microarray (Agilent Technologies, Germany) containing 56000 barley oligonucleotides was used for transcriptome analysis on flag leaves of spring barley. The network correlation of transcripts involved in secondary and RNA metabolism revealed a higher number of positive than negative correlations, of which a signal molecule, ABH1-Cap binding protein showed the highest connectivity to other transcripts. Statistical test showed a strong positive interrelation between ABH1-Cap binding protein and a key gene of phenylpropanoid pathway, Cinnamoyl-CoA reductase. The integrated data suggested Cinnamoyl-CoA reductase (CCR) might be used as putative biomarker for engineering of lignocellulose biomass improvement at the generative stage in barley.

Salinity is one of the main osmotic stresses that limit plants growth and development through changes in osmotic and ionic balances. In order to mapping of genomic regions of controlling quantitative trait locus (QTLs), related to salinity tolerance in grain barley and assessment of associated indices, an experiment was conducted during 2015 using 72 double haploid lines of barley along with their parents (Stepto and Morex) in randomized complete block design (RCBD) with two replications, at three conditions including normal and two salinity levels of NaCl (100 and 200 mM NaCl). Investigated traits in this study were coefficient of velocity of germination, final germination percentage, mean germination time, germination rate index and average germination speed. QTL analysis using composite interval mapping (CIM) was performed based on mean of three environments. Overall, for different traits 47 QTL with LOD≥2.5 was identified and 7 additive-by-additive significant epistatic effects were observed. Total phenotypic variance explained by the QTLs varied from 29.97 to 77.15 percent, which the lowest related to germination rate index under stress conditions of 200 mM and the highest related to coefficient of velocity of germination in normal conditions. The highest LOD (8.27) was obtained for coefficient of velocity of germination on chromosome of 4Hb under 100 mM stress conditions. Stable QTLs in three environments as well as linked markers could be used in the marker assisted selection (MAS) to improve germination characteristics under salinity conditions at different trials replicated over years.

Soil microorganisms with potential for alleviation of salt stress in combination with plant growth promotion would be a promising approach in sustainable agriculture. In the present study, interaction of two varieties of bread wheat (Triticum aestivum L.), Pishtaz and Zarrin and three salt tolerant ectoines producing bacteria including S. Cellulosae, S. rimosus C-2012 and Streptomyces Strain S2 was undertaken in normal and salt conditions. Diversity and distribution of 16S rRNA gene of rhizospheric bacteria in soil inoculated with Streptomyces in salt and normal conditions were studied by denaturing gradient gel electrophoresis (PCR-DGGE) method. Results showed that bacterial cell free extract of all strains reduced root length but S2 and C-2012 increased plant dry weight related to control. Soil treatment with strain C-2012 increased Pishtaz root and shoot fresh and dry weight and Zarrin root fresh and dry weight in normal conditions. At salt conditions, plant growth promotion of C-2012 limited to increase Pishtaz root fresh and dry weight and Zarrin leaf area. Root extract of wheat plantlets increased C- 2012 population (cfu) and decreased mycellial aggregation. The effect of Pishtaz root extract on bacterial cfu was more than Zarrin. Based on PCRDGGE data, the diversity of 16S rRNA gene in rhizosphere changed when Streptomyces or salt was added to soil. PCR-DGGE profiles of 16S rRNA gene in rhizosphere of wheat varieties were also different. Our observations certify that beneficial role of salt tolerant Streptomyces for wheat growth promotion at normal or saline conditions is plant variety dependent.

Defects in pollen carbohydrate metabolism plays an important role in inducing male sterility in wheat plants under drought stress. In order to examine the expression of four genes (Inv1, Inv3, Raftin a and AGP) involved in carbohydrate metabolism under drought condition in two contrasting cultivars, a factorial experiment was established via randomized complete block design. Cultivars (Dezful 10/ Shiraz) were selected as the first factor and drought at meiosis stage (control/stress) as the second factor. After preparation of anther samples at meiosis stage, expression of genes was analyzed through real-time PCR. Expression of Inv, Inv3 Raftin a and AGP genes under drought stress showed no significant change compared to wellwatered (control) condition at drought sensitive cultivar (Shiraz) while they significantly increased at the tolerant one (Dezful 10), by 35, 22, 65 and 9.8 fold change respectively. On the other hand, the percentage of decrease in the fertile florets under drought stress in the tolerant cultivar was significantly less than the sensitive one. Based on the achieved results, the tolerance of Dezful 10 to drought stress can be partially due to the induction of starch accumulation related genes. Also, induction of these genes in sensitive cultivars may reduce their male sterility under drought stress, through compensating a normal level of starch accumulation at pollens.