title: Mechanisms of hormonal regulation of endosperm cap-specific gene expression in tomato seeds.
abstract: The micropylar region of endosperm in a seed, which is adjacent to the radicle tip, is called the 'endosperm cap', and is specifically activated before radicle emergence. This activation of the endosperm cap is a widespread phenomenon among species and is a prerequisite for the completion of germination. To understand the mechanisms of endosperm cap-specific gene expression in tomato seeds, GeneChip analysis was performed. The major groups of endosperm cap-enriched genes were pathogenesis-, cell wall-, and hormone-associated genes. The promoter regions of endosperm cap-enriched genes contained DNA motifs recognized by ethylene response factors (ERFs). The tomato ERF1 (TERF1) and its experimentally verified targets were enriched in the endosperm cap, suggesting an involvement of the ethylene response cascade in this process. The known endosperm cap enzyme endo-β-mannanase is induced by gibberellin (GA), which is thought to be the major hormone inducing endosperm cap-specific genes. The mechanism of endo-β-mannanase induction by GA was also investigated using isolated, embryoless seeds. Results suggested that GA might act indirectly on the endosperm cap. We propose that endosperm cap activation is caused by the ethylene response of this tissue, as a consequence of mechanosensing of the increase in embryonic growth potential by GA action.
authors.affiliation: Department of Horticulture, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Cristina
authors.initials: C
authors.lastname: Martínez-Andújar
authors.forename: Wioletta E
authors.initials: WE
authors.lastname: Pluskota
authors.forename: George W
authors.initials: GW
authors.lastname: Bassel
authors.forename: Masashi
authors.initials: M
authors.lastname: Asahina
authors.forename: Piotr
authors.initials: P
authors.lastname: Pupel
authors.forename: Theresa T
authors.initials: TT
authors.lastname: Nguyen
authors.forename: Noriko
authors.initials: N
authors.lastname: Takeda-Kamiya
authors.forename: David
authors.initials: D
authors.lastname: Toubiana
authors.forename: Bing
authors.initials: B
authors.lastname: Bai
authors.forename: Ryszard J
authors.initials: RJ
authors.lastname: Górecki
authors.forename: Aaron
authors.initials: A
authors.lastname: Fait
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nonogaki
mesh_terms: D001483:Base Sequence; D002473:Cell Wall / Q000235:genetics; D056625:Endosperm / Q000187:drug effects / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018525:Germination; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics*; D008969:Molecular Sequence Data; D059372:Nucleotide Motifs; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D012639:Seeds / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D044902:beta-Mannosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D005030:Ethylenes; D005875:Gibberellins; C036216:ethylene; D044902:beta-Mannosidase