AUXIN RESPONSE FACTOR8 is a negative regulator of fruit initiation in Arabidopsis.
Fruit and seed formation in plants is normally initiated after pollination and fertilization, and, in the absence of fertilization, flowers senesce. In the Arabidopsis thaliana mutant fruit without fertilization, a mutation in AUXIN RESPONSE FACTOR8 (ARF8) results in the uncoupling of fruit development from pollination and fertilization and gives rise to seedless (parthenocarpic) fruit. Parthenocarpy was confirmed in two additional recessive alleles and was caused by mutations within the coding region of ARF8. Genetic experiments indicate that ARF8 acts as an inhibitor to stop further carpel development in the absence of fertilization and the generation of signals required to initiate fruit and seed development. Expression of ARF8 was found to be regulated at multiple levels, and transcriptional autoregulation of ARF8 was observed. Analysis of plants transformed with a transcriptional P(ARF8):beta-glucuronidase (GUS) construct or a translational ARF8:GUS fusion construct displayed distinct developmental regulation of the reporter in floral tissues involved in pollination and fertilization and in the carpel wall. After fertilization, the level of GUS activity declined in the developing seed, while in unfertilized ovules that are destined to senesce, ARF8:GUS expression spread throughout the ovule. This is consistent with a proposed role for ARF8 in restricting signal transduction processes in ovules and growth in pistils until the fruit initiation cue.
Goetz
Marc
M
Commonwealth Scientific and Industrial Research Organization, Division of Plant Industry, Horticulture Unit, Glen Osmond, SA 5064, Australia.
Vivian-Smith
Adam
A
Johnson
Susan D
SD
Koltunow
Anna M
AM
D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005306:Fertilization; D035264:Flowers / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D005638:Fruit / Q000033:anatomy & histology / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000032:analysis; D009154:Mutation; D010641:Phenotype; D020161:Physical Chromosome Mapping; D030821:Plants, Genetically Modified / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012639:Seeds / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C495666:auxin response factor 8, Arabidopsis; D005966:Glucuronidase