Potential role of the regulatory miR1119-MYC2 module in wheat (Triticum aestivum L.) drought tolerance.

MicroRNA (miRNA)-target gene modules are essential components of plants' abiotic stress signalling pathways Little is known about the drought-responsive miRNA-target modules in wheat, but systems biology approaches have enabled the prediction of these regulatory modules and systematic study of their roles in responses to abiotic stresses. Using such an approach, we sought miRNA-target module(s) that may be differentially expressed under drought and non-stressed conditions by mining Expressed Sequence Tag (EST) libraries of wheat roots and identified a strong candidate (miR1119-MYC2). We then assessed molecular and physiochemical differences between two wheat genotypes with contrasting drought tolerance in a controlled drought experiment and assessed possible relationships between their tolerance and evaluated traits. We found that the miR1119-MYC2 module significantly responds to drought stress in wheat roots. It is differentially expressed between the contrasting wheat genotypes and under drought versus non-stressed conditions. We also found significant associations between the module's expression profiles and ABA hormone content, water relations, photosynthetic activities, H2O2 levels, plasma membrane damage, and antioxidant enzyme activities in wheat. Collectively, our results suggest that a regulatory module consisting of miR1119 and MYC2 may play an important role in wheat's drought tolerance.

Integrative System Biology Analysis of Transcriptomic Responses to Drought Stress in Soybean (Glycine max L.).

Drought is a major abiotic stressor that causes yield losses and limits the growing area for most crops. Soybeans are an important legume crop that is sensitive to water-deficit conditions and suffers heavy yield losses from drought stress. To improve drought-tolerant soybean cultivars through breeding, it is necessary to understand the mechanisms of drought tolerance in soybeans. In this study, we applied several transcriptome datasets obtained from soybean plants under drought stress in comparison to those grown under normal conditions to identify novel drought-responsive genes and their underlying molecular mechanisms. We found 2168 significant up/downregulated differentially expressed genes (DEGs) and 8 core modules using gene co-expression analysis to predict their biological roles in drought tolerance. Gene Ontology and KEGG analyses revealed key biological processes and metabolic pathways involved in drought tolerance, such as photosynthesis, glyceraldehyde-3-phosphate dehydrogenase and cytokinin dehydrogenase activity, and regulation of systemic acquired resistance. Genome-wide analysis of plants' cis-acting regulatory elements (CREs) and transcription factors (TFs) was performed for all of the identified DEG promoters in soybeans. Furthermore, the PPI network analysis revealed significant hub genes and the main transcription factors regulating the expression of drought-responsive genes in each module. Among the four modules associated with responses to drought stress, the results indicated that GLYMA_04G209700, GLYMA_02G204700, GLYMA_06G030500, GLYMA_01G215400, and GLYMA_09G225400 have high degrees of interconnection and, thus, could be considered as potential candidates for improving drought tolerance in soybeans. Taken together, these findings could lead to a better understanding of the mechanisms underlying drought responses in soybeans, which may useful for engineering drought tolerance in plants.

Transient expression of fusion and hemagglutinin-neuraminidase epitopes of Newcastle disease virus in maize as a potent candidate vaccine.

PURPOSE: Newcastle disease (ND) represents a major viral disease across the world which imposes high costs to poultry producers for vaccination. Hemagglutinin-neuraminidase (HN) and fusion (F) proteins are the major immunogenic epitopes of Newcastle disease virus and hence, have been the main targets for development of anti-ND vaccines. This paper reports transient expression of a synthetic gene composing of four tandem repeats of HN and three tandem repeats of F epitopes in maize leaves as initial step toward production of recombinant vaccine against ND. MATERIALS AND METHODS: The synthetic gene was cloned in pBI121 plasmid to yield an expression vector. The vector was sophisticated by the addition of AUG codon, polyhistidine-tag, tobacco mosaic virus omega sequence, stop codon, and restriction sites. Leaf transformation was conducted by the agroinfiltration method. Molecular detection assays including polymerase chain reaction, reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA) were carried out to evaluate transgene expression in infiltrated leaves of the corn plant. RESULTS: The result obtained in this research revealed that the transgene was transcribed and translated in maize leaves only 48 hours after infiltration. In the second phase of the experiment, the expressed protein was injected into rabbits. The result of the ELISA assay indicated induction of immune response in the rabbits after injection with the heterologous protein. CONCLUSION: These results confirm the feasibility of agroinfiltration for transient gene expression of viral epitopes in monocot plants which naturally resist stable transformation by Agrobacterium tumefaciens. Practical implications of this finding are discussed in detail and some recommendations for future studies are proposed.

Induction of Immune Response in Animal Model Using Recombinant Anti-NDV Vaccine.

BACKGROUND: Newcastle disease is a major avian disease that causes enormous economic loss in poultry industry. There have been a number of reports on the suitability of plant-based recombinant vaccine against this disease. Fusion (F) and hemagglutinin-neuraminidase (HN) epitopes of the Newcastle disease virus (NDV) represent the major immunogenic sites for development of recombinant anti-ND vaccines in plant hosts. OBJECTIVES: The main objective of this research was to evaluate the ability of a recombinant anti-ND vaccine in induction of immune responses in animal model. MATERIALS AND METHODS: In this study, immunogenicity of recombinant fusion (F) and hemagglutinin-neuraminidase (HN) epitopes of the Newcastle disease virus (NDV) is investigated in an animal model. The corresponding genes encoding amino acids 65-81 of the F protein and 346-353 amino acids of HN were expressed in tobacco seedling using agrobacterium-mediated transformation. Expression of the foreign gene in the tobacco seedlings was investigated by a number of molecular assays including Real-Time PCR and ELISA. Transgenic plant extract was used to induce immunogenic response in animal model. RESULTS: Integration of the foreign gene in plant host genome was confirmed by polymerase chain reaction (PCR). Expression of the foreign recombinant protein was confirmed by Real-Time PCR and ELISA assays. Immunogenicity of the recombinant protein was investigated in rabbit by subcutaneous injection. Results indicated that the transgenic plant extract can induce immune responses in the host as confirmed by presence of specific antibodies in the sera in ELISA assay. Western blot assays showed that the foreign gene was actually expressed in transgenic seedlings. CONCLUSIONS: The results obtained in this research provide further evidence on applicability of plant-based recombinant vaccines for protection of poultry against Newcastle disease.

Integrative meta-analysis of transcriptomic responses to abiotic stress in cotton.

Abiotic environmental stresses are important factors that limit the growth, fiber yield, and quality of cotton. In this study, an integrative meta-analysis and a system-biology analysis were performed to explore the underlying transcriptomic mechanisms that are critical for response to stresses. From the meta-analysis, it was observed that a total of 1465 differentially expressed genes (DEGs) between normal and stress conditions. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that DEGs were significantly enriched in the ubiquitin-dependent process, biosynthesis of secondary metabolites, plant hormone, and signaled transduction. The results also indicated that some of DEGs were assigned to transcription factors (TFs). A total of 148 TFs belonged to 25 conserved families were identified that among them S1Fa-like, ERF, NAC, bZIP families, were the most abundant groups. Moreover, we searched in upstream regions of DEGs for over-represented DNA motifs and were able to identify 11 conserved sequence motifs. The functional analysis of these motifs revealed that they were involved in regulation of transcription, DNA replication, cytoskeleton organization, and translation. Weighted gene co-expression network analysis (WGCNA) uncovered 12 distinct co-expression modules. Four modules were significantly associated with genes involved in response to stress and cell wall organization. The network analysis also identified hub genes such as RTNLB5 and PRA1, which may be involved in regulating stress response. The findings could help to understand the mechanisms of response to abiotic stress and introduce candidate genes that may be beneficial to cotton plant breeding programs.