title: A transcriptional timetable of autumn senescence.
abstract: BACKGROUND
  We have developed genomic tools to allow the genus Populus (aspens and cottonwoods) to be exploited as a full-featured model for investigating fundamental aspects of tree biology. We have undertaken large-scale expressed sequence tag (EST) sequencing programs and created Populus microarrays with significant gene coverage. One of the important aspects of plant biology that cannot be studied in annual plants is the gene activity involved in the induction of autumn leaf senescence.
  
  
  RESULTS
  On the basis of 36,354 Populus ESTs, obtained from seven cDNA libraries, we have created a DNA microarray consisting of 13,490 clones, spotted in duplicate. Of these clones, 12,376 (92%) were confirmed by resequencing and all sequences were annotated and functionally classified. Here we have used the microarray to study transcript abundance in leaves of a free-growing aspen tree (Populus tremula) in northern Sweden during natural autumn senescence. Of the 13,490 spotted clones, 3,792 represented genes with significant expression in all leaf samples from the seven studied dates.
  
  
  CONCLUSIONS
  We observed a major shift in gene expression, coinciding with massive chlorophyll degradation, that reflected a shift from photosynthetic competence to energy generation by mitochondrial respiration, oxidation of fatty acids and nutrient mobilization. Autumn senescence had much in common with senescence in annual plants; for example many proteases were induced. We also found evidence for increased transcriptional activity before the appearance of visible signs of senescence, presumably preparing the leaf for degradation of its components.
authors.affiliation: Department of Biotechnology, KTH - Royal Institute of Technology, AlbaNova University Center, SE-106 91 Stockholm, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Andersson
authors.forename: Johanna
authors.initials: J
authors.lastname: Keskitalo
authors.forename: Andreas
authors.initials: A
authors.lastname: Sjödin
authors.forename: Rupali
authors.initials: R
authors.lastname: Bhalerao
authors.forename: Fredrik
authors.initials: F
authors.lastname: Sterky
authors.forename: Kirsten
authors.initials: K
authors.lastname: Wissel
authors.forename: Karolina
authors.initials: K
authors.lastname: Tandre
authors.forename: Henrik
authors.initials: H
authors.lastname: Aspeborg
authors.forename: Richard
authors.initials: R
authors.lastname: Moyle
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Ohmiya
authors.forename: Rishikesh
authors.initials: R
authors.lastname: Bhalerao
authors.forename: Amy
authors.initials: A
authors.lastname: Brunner
authors.forename: Petter
authors.initials: P
authors.lastname: Gustafsson
authors.forename: Jan
authors.initials: J
authors.lastname: Karlsson
authors.forename: Joakim
authors.initials: J
authors.lastname: Lundeberg
authors.forename: Ove
authors.initials: O
authors.lastname: Nilsson
authors.forename: Göran
authors.initials: G
authors.lastname: Sandberg
authors.forename: Steven
authors.initials: S
authors.lastname: Strauss
authors.forename: Björn
authors.initials: B
authors.lastname: Sundberg
authors.forename: Mathias
authors.initials: M
authors.lastname: Uhlen
authors.forename: Stefan
authors.initials: S
authors.lastname: Jansson
authors.forename: Peter
authors.initials: P
authors.lastname: Nilsson
mesh_terms: D000375:Aging / Q000235:genetics*; D016923:Cell Death / Q000235:genetics; D002909:Chronobiology Phenomena / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling / Q000379:methods; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D015723:Gene Library; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D018515:Plant Leaves / Q000235:genetics; D032107:Populus / Q000166:cytology / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D012621:Seasons; D017422:Sequence Analysis, DNA / Q000379:methods; D014158:Transcription, Genetic / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D018744:DNA, Plant; D018749:RNA, Plant