title: The role of ethylene in the regulation of ovary senescence and fruit set in tomato (Solanum lycopersicum).
abstract: Fruit set is the developmental transition from ovary to young fruit, and generally requires pollination and fertilization. Although the mechanism for fruit set remains elusive, several lines of evidence have demonstrated that fruit set is triggered by activated metabolism of or increased sensitivity to the plant hormones auxin or gibberellins (GAs), which stimulate cell division and expansion within the ovary. Our recent study with tomato (Solanum lycopersicum) suggested that the gaseous hormone ethylene connects auxin and GA, suppressing initiation of fruit set by down-regulating GA accumulation. By contrast, reduced sensitivity to ethylene triggers accumulation of GA, but not auxin, through increasing bioactive GA biosynthesis and decreasing GA inactivation. These changes induce parthenocarpy accompanied by pollination-independent cell expansion in the ovary. Here, we provide evidence that ethylene likely promotes mRNA expression of the senescence-associated genes SlSAG12 and SlNAP in unpollinated ovaries. These results suggest that ethylene acts downstream of auxin and upstream of GA, and also suggest that ethylene promotes senescence of ovary that fail to set fruit in tomato.
authors.affiliation: a Graduate School of Environmental Sciences, Gene Research Center, University of Tsukuba , Tsukuba , Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Shinozaki
authors.affiliation: a Graduate School of Environmental Sciences, Gene Research Center, University of Tsukuba , Tsukuba , Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ezura
authors.affiliation: a Graduate School of Environmental Sciences, Gene Research Center, University of Tsukuba , Tsukuba , Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Ariizumi
mesh_terms: D005030:Ethylenes / Q000378:metabolism*; D035264:Flowers / Q000378:metabolism* / Q000502:physiology*; D005638:Fruit / Q000378:metabolism* / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D018551:Solanum lycopersicum / Q000378:metabolism* / Q000502:physiology*; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism
chemical_list: D005030:Ethylenes; D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; C036216:ethylene
keywords: Auxin; Solanum lycopersicum; ethylene; fruit set; gibberellin; parthenocarpy