title: Temporal expression patterns of hormone metabolism genes during imbibition of Arabidopsis thaliana seeds: a comparative study on dormant and non-dormant accessions.
abstract: Seed imbibition is a prerequisite for subsequent dormancy and germination control. Here, we investigated imbibition responses of Arabidopsis seeds by transcriptomic and hormone profile analyses using dormant [Cape Verde Islands (Cvi)] and non-dormant [Columbia (Col)] accessions. Once imbibed, seeds of both accessions swelled most up to 3 h, reflecting water uptake. Microarray analysis showed that in both accessions, seeds imbibed for 15 min, 30 min and 1 h were less active in gene expression than at 3 h. More than 2,000 genes were either up-regulated or down-regulated in seeds imbibed for 3 h. Some genes up-regulated at 3 h were already induced in seeds imbibed for 1 h, suggestive of genome reprogramming early after the onset of imbibition. Imbibition-induced genes in seeds imbibed for 3 h included those up-regulated in both Col and Cvi (common) or unique to either accession (accession specific). Up-regulated genes that were both common and Cvi-specific were over-represented for sugar metabolism and the pentose phosphate pathway, whereas Col-specific genes were over-represented for ribosomal protein genes. Quantification of plant hormones showed that ABA and salicylic acid (SA) contents were higher, but gibberellin A(4) (GA(4)), N(6)-(Delta(2)-isopentenyl)adenine (iP), jasmonic acid (JA), JA-isoleucine (JA-Ile) and IAA were lower in imbibed seeds of Cvi compared with Col. In addition, changes in IAA and JA were initiated before 1 h, whereas ABA and JA-Ile declined 3 h after the onset of imbibition. An increase in GA(4) and iP appeared to be correlated temporally with the initiation of secondary water uptake, which marks the completion of germination.
authors.affiliation: Growth Regulation Research Group, RIKEN Plant Science Center, 1-7-22, Suehiro-cho, Tsurumi, Yokohama, 230-0045, Japan.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Preston
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Tatematsu
authors.forename: Yuri
authors.initials: Y
authors.lastname: Kanno
authors.forename: Tokunori
authors.initials: T
authors.lastname: Hobo
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kimura
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Yano
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Eiji
authors.initials: E
authors.lastname: Nambara
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018525:Germination; D020411:Oligonucleotide Array Sequence Analysis; D010937:Plant Growth Regulators / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics; D012639:Seeds / Q000235:genetics / Q000502:physiology*; D013997:Time Factors; D015854:Up-Regulation; D014867:Water / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D018749:RNA, Plant; D014867:Water