title: Transcriptome profiling uncovers metabolic and regulatory processes occurring during the transition from desiccation-sensitive to desiccation-tolerant stages in Medicago truncatula seeds.
abstract: To investigate regulatory processes and protective mechanisms leading to desiccation tolerance (DT) in seeds, 16086-element microarrays were used to monitor changes in the transcriptome of desiccation-sensitive 3-mm-long radicles of Medicago truncatula seeds at different time points during incubation in a polyethylene glycol (PEG) solution at -1.7 MPa, resulting in a gradual re-establishment of DT. Gene profiling was also performed on embryos before and after the acquisition of DT during maturation. More than 1300 genes were differentially expressed during the PEG incubation. A large number of genes involved in C metabolism are expressed during the re-establishment of DT. Quantification of C reserves confirms that lipids, starch and oligosaccharides were mobilised, coinciding with the production of sucrose during the early osmotic adjustment. Several clusters of gene profiles were identified with different time-scales. Genes expressed early during the PEG incubation belonged to classes involved in early stress and adaptation responses. Interestingly, several regulatory genes typically expressed during abiotic/drought stresses were also upregulated during maturation, arguing for the partial overlap of ABA-dependent and -independent regulatory pathways involved in both drought and DT. At later time points, in parallel to the re-establishment of DT, upregulated genes are comparable with those involved in late seed maturation. Concomitantly, a massive repression of genes belonging to numerous classes occurred, including cell cycle, biogenesis, primary and energy metabolism. The re-establishment of DT in the germinated radicles appears to concur with a partial return to the quiescent state prior to germination.
authors.affiliation: Unité Mixte de Recherche 1191 Physiologie Moléculaire des Semences, Université d'Angers/INH/INRA, 16 Bd Lavoisier, 49045 Angers, France.
authors.forename: Julia
authors.initials: J
authors.lastname: Buitink
authors.forename: Jean J
authors.initials: JJ
authors.lastname: Leger
authors.forename: Isabelle
authors.initials: I
authors.lastname: Guisle
authors.forename: Benoit Ly
authors.initials: BL
authors.lastname: Vu
authors.forename: Sylvie
authors.initials: S
authors.lastname: Wuillème
authors.forename: Guillaume
authors.initials: G
authors.lastname: Lamirault
authors.forename: Alice
authors.initials: A
authors.lastname: Le Bars
authors.forename: Nolwenn
authors.initials: N
authors.lastname: Le Meur
authors.forename: Anke
authors.initials: A
authors.lastname: Becker
authors.forename: Helge
authors.initials: H
authors.lastname: Küster
authors.forename: Olivier
authors.initials: O
authors.lastname: Leprince
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D016000:Cluster Analysis; D003890:Desiccation; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018525:Germination; D007700:Kinetics; D046913:Medicago truncatula / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D011092:Polyethylene Glycols; D013395:Sucrose; D000040:Abscisic Acid; D002244:Carbon