title: Overexpression of a gibberellin inactivation gene alters seed development, KNOX gene expression, and plant development in Arabidopsis.
abstract: We have examined the role of gibberellins (GAs) in plant development by expression of the pea GA 2-oxidase2 (PsGA2ox2) cDNA, which encodes a GA inactivating enzyme, under the control of the MEDEA (MEA) promoter. Expression of MEA:PsGA2ox2 in Arabidopsis caused seed abortion, demonstrating that active GAs in the endosperm are essential for normal seed development. MEA:PsGA2ox2 plants had reduced ovule number per ovary and exhibited defects in phyllotaxy and leaf morphology which were partly suppressed by GA treatment. The leaf architecture and phyllotaxy defects of MEA:PsGA2ox2 plants were also restored by sly1-d which reduces DELLA protein stability to increase GA response. MEA:PsGA2ox2 seedlings had increased expression of the KNOTTED1-like homeobox (KNOX) genes, BP, KNAT2 and KNAT6, which are known to control plant architecture. The expression of KNOX genes is also altered in wild-type plants treated with GA. These results support the conclusion that GAs can suppress the effects of elevated KNOX gene expression, and raise the possibility that localized changes in GA levels caused by PsGA2ox2 alter the expression of KNOX genes to modify plant architecture.
authors.affiliation: CSIRO, Plant Industry, PMB, Merbein, VIC, Australia. dp.singh@csiro.au
authors.forename: Davinder Pal
authors.initials: DP
authors.lastname: Singh
authors.forename: Fiona F
authors.initials: FF
authors.lastname: Filardo
authors.forename: Richard
authors.initials: R
authors.lastname: Storey
authors.forename: Angelica M
authors.initials: AM
authors.lastname: Jermakow
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Swain
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D018532:Pisum sativum / Q000201:enzymology* / Q000235:genetics; D018515:Plant Leaves / Q000254:growth & development / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012639:Seeds / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D005875:Gibberellins; D018398:Homeodomain Proteins; C405985:Knox1 protein, plant; D010940:Plant Proteins; D006899:Mixed Function Oxygenases; C121463:gibberellin 2-dioxygenase