- Interactive Effects of Elevated [CO2] and Water Stress on Physiological Traits and Gene Expression during Vegetative Growth in Four Durum Wheat Genotypes. [Journal Article]
- FPFront Plant Sci 2016; 7:1738
- The interaction of elevated [CO2] and water stress will have an effect on the adaptation of durum wheat to future climate scenarios. For the Mediterranean basin these scenarios include the rising occ...
The interaction of elevated [CO2] and water stress will have an effect on the adaptation of durum wheat to future climate scenarios. For the Mediterranean basin these scenarios include the rising occurrence of water stress during the first part of the crop cycle. In this study, we evaluated the interactive effects of elevated [CO2] and moderate to severe water stress during the first part of the growth cycle on physiological traits and gene expression in four modern durum wheat genotypes. Physiological data showed that elevated [CO2] promoted plant growth but reduced N content. This was related to a down-regulation of Rubisco and N assimilation genes and up-regulation of genes that take part in C-N remobilization, which might suggest a higher N efficiency. Water restriction limited the stimulation of plant biomass under elevated [CO2], especially at severe water stress, while stomatal conductance and carbon isotope signature revealed a water saving strategy. Transcript profiles under water stress suggested an inhibition of primary C fixation and N assimilation. Nevertheless, the interactive effects of elevated [CO2] and water stress depended on the genotype and the severity of the water stress, especially for the expression of drought stress-responsive genes such as dehydrins, catalase, and superoxide dismutase. The network analysis of physiological traits and transcript levels showed coordinated shifts between both categories of parameters and between C and N metabolism at the transcript level, indicating potential genes and traits that could be used as markers for early vigor in durum wheat under future climate change scenarios. Overall the results showed that greater plant growth was linked to an increase in N content and expression of N metabolism-related genes and down-regulation of genes related to the antioxidant system. The combination of elevated [CO2] and severe water stress was highly dependent on the genotypic variability, suggesting specific genotypic adaptation strategies to environmental conditions.
- The role of the nifB1 and nifB2 promoters in cell-type-specific expression of two Mo-nitrogenases in the cyanobacterium Anabaena variabilis ATCC 29413. [Journal Article]
- JBJ Bacteriol 2016 Dec 05
- Anabaena variabilis ATCC 29413 has one Mo-nitrogenase that is made under oxic growth conditions in specialized cells called heterocysts and a second Mo-nitrogenase that is made only under anoxic cond...
Anabaena variabilis ATCC 29413 has one Mo-nitrogenase that is made under oxic growth conditions in specialized cells called heterocysts and a second Mo-nitrogenase that is made only under anoxic conditions in vegetative cells. The two large nif gene clusters responsible for these two nitrogenases are under the control of the promoter of the first gene, nifB1 or nifB2, in the operon. Despite differences in expression patterns of nifB1 and nifB2 related to oxygen and cell type, the regions upstream of their transcription start sites (tss) show striking homology, including three highly conserved sequences (CS). CS1 and CS2 and the region just upstream from the tss were required for optimal expression from the nifB1 promoter, but CS3 and the 5' untranslated region (UTR) were not. Hybrid fusions of the nifB1 and nifB2 upstream regions revealed that the region including CS1, CS2, and CS3 of nifB2 could substitute for the similar region of nifB1; however, the converse was not true. Expression from the nifB2 promoter region required the CS1, CS2, and CS3 regions of nifB2 and also required the nifB2 5' UTR. A hybrid promoter that was mostly nifB2, but with the region from about -40 to the tss of nifB1, was expressed in heterocysts and in anoxic vegetative cells. Thus, addition of the nifB1 promoter region (from about -40 to the tss of nifB1) in the nifB hybrid promoter supported expression in heterocysts, but did not prevent the mostly nifB2 promoter from also functioning in anoxic vegetative cells.
- The Core Subunit of A Chromatin-Remodeling Complex, ZmCHB101, Plays Essential Roles in Maize Growth and Development. [Journal Article]
- SRSci Rep 2016 Dec 05; 6:38504
- ATP-dependent chromatin remodeling complexes play essential roles in the regulation of diverse biological processes by formulating a DNA template that is accessible to the general transcription appar...
ATP-dependent chromatin remodeling complexes play essential roles in the regulation of diverse biological processes by formulating a DNA template that is accessible to the general transcription apparatus. Although the function of chromatin remodelers in plant development has been studied in A. thaliana, how it affects growth and development of major crops (e.g., maize) remains uninvestigated. Combining genetic, genomic and bioinformatic analyses, we show here that the maize core subunit of chromatin remodeling complex, ZmCHB101, plays essential roles in growth and development of maize at both vegetative and reproductive stages. Independent ZmCHB101 RNA interference plant lines displayed abaxially curling leaf phenotype due to increase of bulliform cell numbers, and showed impaired development of tassel and cob. RNA-seq-based transcriptome profiling revealed that ZmCHB101 dictated transcriptional reprogramming of a significant set of genes involved in plant development, photosynthesis, metabolic regulation, stress response and gene expressional regulation. Intriguingly, we found that ZmCHB101 was required for maintaining normal nucleosome density and 45 S rDNA compaction. Our findings suggest that the SWI3 protein, ZmCHB101, plays pivotal roles in maize normal growth and development via regulation of chromatin structure.
- Multiple evolutionary trajectories have led to the emergence of races in Fusarium oxysporum f. sp. lycopersici. [Journal Article]
- AEAppl Environ Microbiol 2016 Dec 02
- Race 1 isolates of Fusarium oxysporum f. sp. lycopersici (Fol) are characterized by the presence of AVR1 in their genome. The product of this gene, Avr1, triggers resistance in tomato cultivars carry...
Race 1 isolates of Fusarium oxysporum f. sp. lycopersici (Fol) are characterized by the presence of AVR1 in their genome. The product of this gene, Avr1, triggers resistance in tomato cultivars carrying resistance gene I In Fol race 2 and race 3 isolates, AVR1 is absent and hence they are virulent on tomato cultivars carrying I In this study, we analyze an approximately 100 kb genomic fragment containing the AVR1 locus of race 1 isolate Fol004, and compare it to the sequenced genome of Fol race 2 isolate 4287 (Fol4287). A genomic fragment of 31 kb containing AVR1 was found to be missing in Fol4287. Further analysis suggests that race 2 evolved from race 1 by deletion of this 31 kb fragment due to a recombination event between two transposable elements bordering the fragment. A worldwide collection of 71 Fol isolates representing races 1, 2 and 3, all known vegetative compatibility groups (VCGs) and five continents was subjected to PCR analysis of the AVR1 locus, including the two bordering transposable elements. Based on phylogenetic analysis using EF1-α, five evolutionary lineages for Fol were identified that correlate well with VCGs. More importantly, we show that Fol races evolved in a stepwise manner within each VCG by the loss of function of avirulence genes in a number of alternative ways.
- WD40-repeat protein MoCreC is essential for carbon repression and is involved in conidiation, growth and pathogenicity of Magnaporthe oryzae. [Journal Article]
- CGCurr Genet 2016 Dec 01
- Carbon catabolite repression (CCR) is a common regulatory mechanism used by microorganisms to prioritize use of a preferred carbon source (usually glucose). The CreC WD40-repeat protein is a major co...
Carbon catabolite repression (CCR) is a common regulatory mechanism used by microorganisms to prioritize use of a preferred carbon source (usually glucose). The CreC WD40-repeat protein is a major component of the CCR pathway in Aspergillus nidulans. To clarify the function of the CreC ortholog from Magnaporthe oryzae in regulating gene expression important for pathogenesis, MoCreC was identified and genetically characterized. The vegetative growth rate of the MoCreC deletion mutant on various carbon sources was reduced. The MoCreC mutant produced fewer conidia and with about 60% of conidia having septation defects. Appressorium formation was impaired in the MoCreC mutant. Although some appressoria of the mutant could penetrate the leaf surface successfully, the efficiency of penetration and invasive growth of infection hyphae was reduced, resulting in attenuated virulence toward host plants. The CCR was defective as the mutant was more sensitive to allyl alcohol in the presence of glucose, and 2-deoxyglucose was unable to fully repress utilization of secondary carbon sources. qRT-PCR results indicated that the genes encoding cell wall degradation enzymes, such as β-glucosidase, feruloyl esterase and exoglucanase, were upregulated in MoCreC mutant. Taken together, we conclude that MoCreC is a major regulator of CCR and plays significant roles in regulating growth, conidiation, and pathogenicity of M. oryzae.
- A comprehensively curated genome-scale two-cell model for the cyanobacterium Anabaena sp. PCC 7120. [Journal Article]
- PPPlant Physiol 2016 Nov 29
- Anabaena sp. PCC 7120 is a nitrogen-fixing filamentous cyanobacterium. Under nitrogen limiting conditions, a fraction of the vegetative cells in each filament terminally differentiate to non-growing ...
Anabaena sp. PCC 7120 is a nitrogen-fixing filamentous cyanobacterium. Under nitrogen limiting conditions, a fraction of the vegetative cells in each filament terminally differentiate to non-growing heterocysts. Heterocysts are metabolically and structurally specialized to enable O2-sensitive nitrogen fixation. The functionality of the filament, as an association of vegetative cells and heterocysts, is postulated to depend on metabolic exchange of electrons, carbon and fixed nitrogen. In the present work, we compile and evaluate a comprehensive curated stoichiometric model of this two-cell system, with the objective function based on the growth of the filament under diazotrophic conditions. The predicted growth rate under nitrogen replete and deplete conditions, as well as the effect of external carbon and nitrogen sources, was thereafter verified. Furthermore, the model was utilized to comprehensively evaluate the optimality of putative metabolic exchange reactions between heterocysts and vegetative cells. The model suggested that optimal growth requires at least four exchange metabolites. Several combinations of exchange metabolites resulted in predicted growth rates that are higher than growth rates achieved by only considering exchange of metabolites previously suggested in the literature. The curated model of the metabolic network of Anabaena sp. PCC 7120 enhances our ability to understand the metabolic organization of multi-cellular cyanobacteria and provides a platform for further study and engineering of their metabolism.
- Overexpression of a Hevea brasiliensis ErbB-3 Binding protein 1 Gene Increases Drought Tolerance and Organ Size in Arabidopsis. [Journal Article]
- FPFront Plant Sci 2016; 7:1703
- Rubber trees are economically important tropical tree species and the major source of natural rubber, which is an essential industrial material. This tropical perennial tree is susceptible to cold st...
Rubber trees are economically important tropical tree species and the major source of natural rubber, which is an essential industrial material. This tropical perennial tree is susceptible to cold stress and other abiotic stresses, especially in the marginal northern tropics. Recent years, the genome sequencing and RNA-seq projects produced huge amount of sequence data, which greatly facilitated the functional genomics study. However, the characterization of individual functional gene is in urgent demands, especially for those involved in stress resistance. Here we identified and characterized the rubber tree gene ErbB-3 binding protein 1, which undergoes changes in expression in response to cold, drought stress and ABA treatment. HbEBP1 overexpression (OE) in Arabidopsis increased organ size, facilitated root growth and increased adult leaf number by delaying the vegetative-to-reproductive transition. In addition, HbEBP1 OE enhanced the resistance of the Arabidopsis plants to freezing and drought stress, demonstrating that this gene participates in the regulation of abiotic stress resistance. RD29a, RD22 and CYCD3;1 expression was also greatly enhanced by HbEBP1 OE, which explains its regulatory roles in organ size and stress resistance. The regulation of drought stress resistance is a novel function identified in plant EBP1 genes, which expands our understanding of the roles of EBP1 gene in response to the environment. Our results provide information that may lead to the use of HbEBP1 in genetically engineered crops to increase both biomass and abiotic stress resistance.
- Systematic deletion of the ER lectin chaperone genes reveals their roles in vegetative growth and male gametophyte development in Arabidopsis. [Journal Article]
- PJPlant J 2016 Nov 26
- Calnexin (CNX) and calreticulin (CRT) are homologous lectin chaperones in the endoplasmic reticulum (ER) that facilitate glycoprotein folding and retain folding intermediates to prevent their transit...
Calnexin (CNX) and calreticulin (CRT) are homologous lectin chaperones in the endoplasmic reticulum (ER) that facilitate glycoprotein folding and retain folding intermediates to prevent their transit via the secretary pathway. The Arabidopsis genome has two CNX (CNX1 and CNX2) and three CRT homologs (CRT1, CRT2, and CRT3). Despite growing evidence of the biological roles of CNXs and CRTs, little is understood about their function in Arabidopsis growth and development under normal conditions. Here, we report that deletion of CNX1, but not of CNX2, in the crt1 crt2 crt3 triple mutation background had adverse effect on pollen viability and pollen tube growth, leading to significant reduction in fertility. The cnx1 crt1 crt2 crt3 quadruple mutation also conferred severe defects in growth and development, including a shortened primary root, increased root hair length and density, and reduced plant height. Disruption of all five members of the CNX/CRT family was revealed to be lethal. Finally, the abnormal phenotype of the cnx1 crt1 crt2 crt3 quadruple mutants was completely rescued by either the CNX1 or CNX2 cDNA under the control of the CNX1 promoter, suggesting functional redundancy between CNX1 and CNX2. Taken together, these results provide genetic evidence that CNX and CRT play essential and overlapping roles during vegetative growth and male gametophyte development in Arabidopsis. This article is protected by copyright. All rights reserved.
- The calmodulin gene in Neurospora crassa is required for normal vegetative growth, ultraviolet survival, and sexual development. [Journal Article]
- AMArch Microbiol 2016 Nov 25
- We isolated a Neurospora crassa mutant of the calmodulin (cmd) gene using repeat-induced point mutation and studied its phenotypes. The cmd (RIP) mutant showed a defect in growth, reduced aerial hyph...
We isolated a Neurospora crassa mutant of the calmodulin (cmd) gene using repeat-induced point mutation and studied its phenotypes. The cmd (RIP) mutant showed a defect in growth, reduced aerial hyphae, decreased carotenoid accumulation, a severe reduction in viability upon ultraviolet (UV) irradiation, and a fertility defect. Moreover, meiotic silencing of the cmd gene resulted in a barren phenotype. In addition, we also performed site-directed mutational analysis of the calcium/calmodulin-dependent kinase-2 (Ca(2+)/CaMK-2), a target of the CaM protein encoded by the cmd gene. The camk-2 (S247A) and the camk-2 (T267A) mutants in a homozygous cross, or in a cross with a Δcamk-2 mutant, displayed an intermediate phenotype, suggesting that serine 247 and threonine 267 phosphorylation sites of the Ca(2+)/CaMK-2 are essential for full fertility in N. crassa. Therefore, CaM in N. crassa is required for normal vegetative growth, UV survival, and sexual development. Additionally, serine 247 and threonine 267 phosphorylation sites are important for the Ca(2+)/CaMK-2 function.
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- Evaluation of stability and validation of reference genes for RT-qPCR expression studies in rice plants under water deficit. [Journal Article]
- JAJ Appl Genet 2016 Nov 23
- Many studies use strategies that allow for the identification of a large number of genes expressed in response to different stress conditions to which the plant is subjected throughout its cycle. In ...
Many studies use strategies that allow for the identification of a large number of genes expressed in response to different stress conditions to which the plant is subjected throughout its cycle. In order to obtain accurate and reliable results in gene expression studies, it is necessary to use reference genes, which must have uniform expression in the majority of cells in the organism studied. RNA isolation of leaves and expression analysis in real-time quantitative polymerase chain reaction (RT-qPCR) were carried out. In this study, nine candidate reference genes were tested, actin 11 (ACT11), ubiquitin conjugated to E2 enzyme (UBC-E2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta tubulin (β-tubulin), eukaryotic initiation factor 4α (eIF-4α), ubiquitin 10 (UBQ10), ubiquitin 5 (UBQ5), aquaporin TIP41 (TIP41-Like) and cyclophilin, in two genotypes of rice, AN Cambará and BRS Querência, with different levels of soil moisture (20%, 10% and recovery) in the vegetative (V5) and reproductive stages (period preceding flowering). Currently, there are different softwares that perform stability analyses and define the most suitable reference genes for a particular study. In this study, we used five different methods: geNorm, BestKeeper, ΔCt method, NormFinder and RefFinder. The results indicate that UBC-E2 and UBQ5 can be used as reference genes in all samples and softwares evaluated. The genes β-tubulin and eIF-4α, traditionally used as reference genes, along with GAPDH, presented lower stability values. The gene expression of basic leucine zipper (bZIP23 and bZIP72) was used to validate the selected reference genes, demonstrating that the use of an inappropriate reference can induce erroneous results.