title: Gene expression in autumn leaves.
abstract: Two cDNA libraries were prepared, one from leaves of a field-grown aspen (Populus tremula) tree, harvested just before any visible sign of leaf senescence in the autumn, and one from young but fully expanded leaves of greenhouse-grown aspen (Populus tremula x tremuloides). Expressed sequence tags (ESTs; 5,128 and 4,841, respectively) were obtained from the two libraries. A semiautomatic method of annotation and functional classification of the ESTs, according to a modified Munich Institute of Protein Sequences classification scheme, was developed, utilizing information from three different databases. The patterns of gene expression in the two libraries were strikingly different. In the autumn leaf library, ESTs encoding metallothionein, early light-inducible proteins, and cysteine proteases were most abundant. Clones encoding other proteases and proteins involved in respiration and breakdown of lipids and pigments, as well as stress-related genes, were also well represented. We identified homologs to many known senescence-associated genes, as well as seven different genes encoding cysteine proteases, two encoding aspartic proteases, five encoding metallothioneins, and 35 additional genes that were up-regulated in autumn leaves. We also indirectly estimated the rate of plastid protein synthesis in the autumn leaves to be less that 10% of that in young leaves.
authors.affiliation: Umea Plant Science Center, Department of Plant Physiology, Umea University, 901 87 Umea, Sweden.
authors.forename: Rupali
authors.initials: R
authors.lastname: Bhalerao
authors.forename: Johanna
authors.initials: J
authors.lastname: Keskitalo
authors.forename: Fredrik
authors.initials: F
authors.lastname: Sterky
authors.forename: Rikard
authors.initials: R
authors.lastname: Erlandsson
authors.forename: Harry
authors.initials: H
authors.lastname: Björkbacka
authors.forename: Simon Jonsson
authors.initials: SJ
authors.lastname: Birve
authors.forename: Jan
authors.initials: J
authors.lastname: Karlsson
authors.forename: Per
authors.initials: P
authors.lastname: Gardeström
authors.forename: Petter
authors.initials: P
authors.lastname: Gustafsson
authors.forename: Joakim
authors.initials: J
authors.lastname: Lundeberg
authors.forename: Stefan
authors.initials: S
authors.lastname: Jansson
mesh_terms: D029681:Arabidopsis Proteins; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism; D019069:Cell Respiration / Q000235:genetics / Q000502:physiology; D019295:Computational Biology; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D030541:Databases, Genetic; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling / Q000379:methods; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D050356:Lipid Metabolism; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics; D018515:Plant Leaves / Q000235:genetics* / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D032107:Populus / Q000235:genetics / Q000254:growth & development; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012621:Seasons
chemical_list: D029681:Arabidopsis Proteins; C078410:ELIP protein, Arabidopsis; D010940:Plant Proteins; D018749:RNA, Plant; D008668:Metallothionein; D003546:Cysteine Endopeptidases; D016282:Aspartic Acid Endopeptidases