title: Global expression profiling in leaves of free-growing aspen.
abstract: BACKGROUND
  Genomic studies are routinely performed on young plants in controlled environments which is very different from natural conditions. In reality plants in temperate countries are exposed to large fluctuations in environmental conditions, in the case of perennials over several years. We have studied gene expression in leaves of a free-growing aspen (Populus tremula) throughout multiple growing seasons
  
  
  RESULTS
  We show that gene expression during the first month of leaf development was largely determined by a developmental program although leaf expansion, chlorophyll accumulation and the speed of progression through this program was regulated by the temperature. We were also able to define "transcriptional signatures" for four different substages of leaf development. In mature leaves, weather factors were important for gene regulation.
  
  
  CONCLUSIONS
  This study shows that multivariate methods together with high throughput transcriptional methods in the field can provide additional, novel information as to plant status under changing environmental conditions that is impossible to mimic in laboratory conditions. We have generated a dataset that could be used to e.g. identify marker genes for certain developmental stages or treatments, as well as to assess natural variation in gene expression.
authors.affiliation: Um eå Plant Science Centre, Department of Plant Physiology, Um eå University, SE-901 87 Um eå, Sweden. andreas.sjodin@plantphys.umu.se
authors.forename: Andreas
authors.initials: A
authors.lastname: Sjödin
authors.forename: Kirsten
authors.initials: K
authors.lastname: Wissel
authors.forename: Max
authors.initials: M
authors.lastname: Bylesjö
authors.forename: Johan
authors.initials: J
authors.lastname: Trygg
authors.forename: Stefan
authors.initials: S
authors.lastname: Jansson
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods*; D018506:Gene Expression Regulation, Plant; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D018515:Plant Leaves / Q000235:genetics*; D032107:Populus / Q000235:genetics*; D025341:Principal Component Analysis; D012621:Seasons; D013696:Temperature
chemical_list: D002734:Chlorophyll