Project description:Growth retardation and stress-induced premature plant senescence are accompanied by a severe yield reduction and raise a major agro-economic concern. To improve biomass and yield in agricultural crops under mild stress conditions, the survival must be changed to productivity mode. Our previous successful attempts to delay premature senescence and growth inhibition under abiotic stress conditions by autoregulation of cytokinins (CKs) levels constitute a generic technology toward the development of highly productive plants. Since this technology is based on the induction of CKs synthesis during the age-dependent senescence phase by a senescence-specific promoter (SARK), which is not necessarily regulated by abiotic stress conditions, we developed autoregulating transgenic plants expressing the IPT gene specifically under abiotic stress conditions. The Arabidopsis promoter of the stress-induced metallothionein gene (AtMT) was isolated, fused to the IPT gene and transformed into tobacco plants. The MT::IPT transgenic tobacco plants displayed comparable elevated biomass productivity and maintained growth under drought conditions. To decipher the role and the molecular mechanisms of CKs in reverting the survival transcriptional program to a sustainable plant growth program, we performed gene expression analysis of candidate stress-related genes and found unexpectedly clear downregulation in the CK-overproducing plants. We also investigated kinase activity after applying exogenous CKs to tobacco cell suspensions that were grown in salinity stress. In-gel kinase activity analysis demonstrated CK-dependent deactivation of several stress-related kinases including two of the MAPK components, SIPK and WIPK and the NtOSAK, a member of SnRK2 kinase family, a key component of the ABA signaling cascade. A comprehensive phosphoproteomics analysis of tobacco cells, treated with exogenous CKs under salinity-stress conditions indicated that >50% of the identified phosphoproteins involved in stress responses were dephosphorylated by CKs. We hypothesize that upregulation of CK levels under stress conditions desensitize stress signaling cues through deactivation of kinases that are normally activated under stress conditions. CK-dependent desensitization of environmental stimuli is suggested to attenuate various pathways of the avoidance syndrome including the characteristic growth arrest and the premature senescence while allowing normal growth and metabolic maintenance.

Project description:Purpose: Trichomes, developing from the epidermis of nearly all terrestrial plants, provide good structural resistance against insect herbivores and an excellent model for studying the molecular mechanisms underlying cell fate determination. Regulation of trichomes in Rosids has been well characterized. However, little is known about the cell proliferation molecular processes during multicellular trichome formation in Asterids. Methods: The transcriptomes of between Wov transgenic and wild-type tobacco by RNA-seq analysis were evaluated using the Illumina HiSeq™ 2000 sequencing platform. Raw sequences were filtered and the resulting sets of clean reads were used for the following analysis by Tophat and DEGseq software. qRT–PCR validation was performed using SYBR Green assays. Results: In this study, we identified two point mutations in a novel allele (Wov) at Wo locus. Ectopic expression of Wov in tobacco and potato induces much more trichome formation than wild type. To gain new insights into the underlying mechanisms during the processes of these trichomes formation, we compared the gene expression profiles between Wov transgenic and wild-type tobacco by RNA-seq analysis. A total of 544 co-DEGs were detected between transgenic and wild-type tobacco. Functional assignments of the co-DEGs indicated that 33 reliable pathways are altered in transgenic tobacco plants. The most noticeable pathways are fatty acid metabolism, amino acid biosynthesis and metabolism, and plant hormone signal transduction. Results suggest that these enhanced processes are critical for the cell proliferation during multicellular trichome formation in transgenic plants. In addition, the transcriptional levels of homologues of trichome regulators in Rosids were not significantly changed, whereas homologues of genes (Wo and SlCycB2) in Asterids were significantly upregulated in Wov transgenic tobacco plants. Conclusions: This study presents a global picture of the gene expression changes induced by Wov- gene in tobacco. And the results provided us new insight into the molecular processes controlling multicellular formation in tobacco. Furthermore, we inferred that trichomes in solanaceous species might share a common network.

Project description:Purpose: Trichomes, developing from the epidermis of nearly all terrestrial plants, provide good structural resistance against insect herbivores and an excellent model for studying the molecular mechanisms underlying cell fate determination. Regulation of trichomes in Rosids has been well characterized. However, little is known about the cell proliferation molecular processes during multicellular trichome formation in Asterids. Methods: The transcriptomes of between Wov transgenic and wild-type tobacco by RNA-seq analysis were evaluated using the Illumina HiSeq™ 2000 sequencing platform. Raw sequences were filtered and the resulting sets of clean reads were used for the following analysis by Tophat and DEGseq software. qRT–PCR validation was performed using SYBR Green assays. Results: In this study, we identified two point mutations in a novel allele (Wov) at Wo locus. Ectopic expression of Wov in tobacco and potato induces much more trichome formation than wild type. To gain new insights into the underlying mechanisms during the processes of these trichomes formation, we compared the gene expression profiles between Wov transgenic and wild-type tobacco by RNA-seq analysis. A total of 544 co-DEGs were detected between transgenic and wild-type tobacco. Functional assignments of the co-DEGs indicated that 33 reliable pathways are altered in transgenic tobacco plants. The most noticeable pathways are fatty acid metabolism, amino acid biosynthesis and metabolism, and plant hormone signal transduction. Results suggest that these enhanced processes are critical for the cell proliferation during multicellular trichome formation in transgenic plants. In addition, the transcriptional levels of homologues of trichome regulators in Rosids were not significantly changed, whereas homologues of genes (Wo and SlCycB2) in Asterids were significantly upregulated in Wov transgenic tobacco plants. Conclusions: This study presents a global picture of the gene expression changes induced by Wov- gene in tobacco. And the results provided us new insight into the molecular processes controlling multicellular formation in tobacco. Furthermore, we inferred that trichomes in solanaceous species might share a common network. The transcriptomes of between Wov transgenic and wild-type tobacco by RNA-seq analysis were evaluated, in duplicate, using the Illumina sequencing platform.

Project description:Nitric oxide (NO) is involved in all major environmental stresses. However, most of these understandings were mainly based on pharmacological study using NO modulator compounds. Recently, our studies together with others provided a new class of plant experimental system with specific in vivo NO release through constitutively overexpressing rat neuronal NO synthase (nNOS) in plants. In this study, we found that the nNOS transgenic Arabidopsis plants displayed lower level of H2O2 content, but higher levels of antioxidant enzyme activities and osmolytes under drought stress conditions. Transcriptomic analysis identified 490 and 20 genes that were differentially expressed in wild type (WT) and nNOS transgenic plants under control and drought stress conditions, respectively. Pathway analysis revealed that many genes involved in photosynthesis, cell, misc, co-factor and vitamin metabolism, major CHO metabolism, OPP and secondary metabolism were largely changed in nNOS vs. WT under control or drought stress conditions. Interestingly, CBF1/2 and 13 zinc finger family proteins, known as important family of transcription regulators in modulating several stress-responsive genes, were differentially expressed by nNOS transgenic effect. Additionally, some genes were commonly regulated by nNOS transgenic and abscisic acid (ABA) effects, indicating new insights to cross-talk between ABA and NO. Taken together, in vivo NO modulated antioxidant enzyme activities, osmolyte level, and the expression of genes involved in several pathways, thereby resulting in enhanced stress tolerance in nNOS transgenic plants. These observations might provide some insights to understand the physiological and molecular mechanisms of NO in response to drought stress in Arabidopsis. Two transgenic Arabidopsis lines (nNOS-2 and nNOS-25) with the nNOS gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter, as well as Col-0 (WT), were used in this research. RNA samples from two nNOS transgenic lines were pooled for cRNA labelling and chip hybridization.

Project description:Comparative analysis of tobacco leaves transcriptomes unveils carotenoid pathway potentially determined the characteristics of aroma compounds in different environmental regions. Tobacco (Nicotiana tabacum) is a sensitive crop to environmental changes, and a tobacco with unique volatile aroma fractions always formed in specific ecological conditions. In order to investigate the differential expressed genes caused by environmental changes and reveal the formation mechanism of characteristics of tobacco in three different aroma tobacco regions of Guizhou Province, Agilent tobacco microarray was adapted for transcriptome comparison of tobacco leaves in medium aroma tobacco region Kaiyang and light aroma tobacco regions Weining and Tianzhu. Results showed that there was big difference among the gene expression profiles of tobacco leaves in different environmental conditions. A total of 517 differential expressed genes (DEGs) between Weining and Tianzhu were identified, while 733 and 1,005 genes differentially expressed between Longgang and another two tobacco regions Weining and Tianzhu, respectively. Compared with Longgang, up-regulated genes in Weining and Tianzhu were likely involved in secondary metabolism pathways, especially carotenoid pathway, including PHYTOENE SYNTHASE, PHYTOENE DEHYDROGENASE, LYCOPENE ε-CYCLASE, CAROTENOID β-HYDROXYLASE and CAROTENOID CLEAVAGE DIOXYGENASE 1 genes, while most down-regulated genes played important roles in response to temperature and light radiation, such as heat shock proteins. Gene Ontology and MapMan analyses demonstrated that the DEGs among different environmental regions were significantly enriched in light reaction of photosystem II, response of stimulus and secondary metabolism, suggesting they played crucial roles in environmental adaptation and accumulation of aroma compounds in tobacco plants. Through comprehensive transcriptome comparison, we not only identified several stress response genes in tobacco leaves from different environmental regions but also highlighted the importance of carotenoid pathway genes for characteristics of aroma compounds in specific growing regions. Our study primarily laid the foundation for further understanding the molecular mechanism of environmental adaptation of tobacco plants and molecular regulation of aroma substances in tobacco leaves.

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Dataset Information

A multi-OMICs approach sheds light on the higher yield phenotype and enhanced abiotic stress tolerance in tobacco lines expressing the carrot lycopene β-cyclase1 gene

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A Multi-OMICs Approach Sheds Light on the Higher Yield Phenotype and Enhanced Abiotic Stress Tolerance in Tobacco Lines Expressing the Carrot <i>lycopene</i> β<i>-cyclase1</i> Gene.

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