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Beijing Forestry University (2013)

Genome-wide Transcriptional Response and Expressed NF-YB Genes of Populus Puphratica to Drought Stress

Yan Dong Hui

Titre : Genome-wide Transcriptional Response and Expressed NF-YB Genes of Populus Puphratica to Drought Stress

Auteur : Yan Dong Hui

Grade : Doctoral Dissertation 2013

Université : Beijing Forestry University

Résumé
Populus euphratica is native to semi-arid regions of the Xinjiang Uyghur Autonomous Region of China, and studying its drought responses will greatly increase the understanding of how trees acclimate to drought. Water was withheld for seven weeks in four different drought stress treatments, with regime1being the least drought stressed and regime4being the most, and the poplar’s transcriptional profiles examined with Affymetrix Poplar GeneChip microarrays. The number of significantly up or down transcriptional changes increased with the severity of drought stress, with regime1,2,3and4showing952,1354,2138and2360altered transcripts, respectively. Only277of these were found in common across all four regimes, while1938transcripts were found to be unique to the individual treatments. Genes with altered transcript abundance included members of the transcription factor families AP2/EREPB, bZIP, NAC, NF-Y, WRKY, MYB and Homeobox, as well as genes for the small HSP, HSP70and HSP90heat shock protein families. Analysis of the transcript data from these experiments indicated that P. euphratica activates specific regulatory pathways according to the degree of drought stress it receives. These results provide important insights into the molecular mechanisms underpinning the drought stress responses of poplar, as well as providing candidates for future experimentation. In addition, to identify and characterize the NF-YB genes in the model tree Populus trichocarpa, with the expectation of determining which orthologs in P. euphratica, were involved in drought response, a total of20NF-YB genes in the P. trichocarpa genome were identified and annotated by bioinformatics procedures. The examination on their phylogenetic relationships and ortholog predictions showed that Populus has an expanded set of NF-YB genes within unknown functional groups in comparison to Arabidopsis. A target sequence with543bp in length, named PeNF-YB7, from leave issues of Populus euphractica via reverse transcription approach, with the NF-YB homologue sequence in the genome of P. trichocarpa as reference. The gene was observed to be expressed in unclear field with GFP subcellular localization method. Four members of the PeNF-YB gene family in P. euphratica were observed to be up-regulated in expression during PEG-6000(polyethylene glycol6000) drought treatment based on RT-qPCR analyses. The results of this study could not only verify the role of20NF-YB genes in poplar resistance to drought, but also provide a basic clue for elucidating regulation mechanism of tree resistance to drought. The increased knowledge on the phylogenetic relationships, predicted orthologs, and expression patterns of the poplar NFYB genes during drought stress can be expected to promote the future study of woody plants.

Mots clés : NF-YB Populus Drought Gene expression profile Microarray

Présentation (Dissertation topics)

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