Molecular cloning of ABNORMAL FLORAL ORGANS: a gene required for flower development in Arabidopsis

We report the cloning and characterization of the gene ABNORMAL FLORAL ORGA NS (AFO), which is required for normal flower development in Arabidopsis. a fo mutant flowers show defects in all four floral whorls. The number of org ans in each whorl varies. Most flowers consist of reduced numbers of petals and stamens, even though supernumerary sepals and carpels may be observed. Abnormal organ structure is evident from an early stage. Mosaic first whor l organs are common, with some sepals taking on petaloid or staminoid chara cteristics. Stamens are often deformed, having thin filaments and reduced a nthers, yet occasionally producing viable pollen. Partial fertility is indi cated by some seed setting. The afo-1 mutation is caused by insertion of a gene trap Ds transposable element. The AFO gene was cloned and is predicted to encode a novel protein of 229 amino acids. The expression of AFO mRNA b y northern blot analysis in combination with mutant phenotype suggests that the AFO gene product plays an important role in Arabidopsis flower develop ment. We also report that antherless, a previously described male-sterile m utation, is allelic to afo-1.