title: The Arabidopsis ABORTED MICROSPORES (AMS) gene encodes a MYC class transcription factor.
abstract: Visual screening of a T-DNA mutagenised population of Arabidopsis thaliana for an absence of silique elongation lead to the isolation of the aborted microspores (ams) mutant that shows a sporophytic recessive male sterile phenotype. Homozygous mutant plants are completely devoid of mature pollen. Pollen degeneration occurs shortly after release of the microspores from the tetrad, prior to pollen mitosis I. Premature tapetum and microspore degeneration are the primary defects caused by this lesion, while a secondary effect is visualised in the stamen filaments, which are reduced in length and lie beneath the receptive stigma at flower opening. The disrupted gene was isolated and revealed a T-DNA element to be inserted into the eighth exon of a basic helix-loop-helix (bHLH) gene located on chromosome II. This protein sequence contains a basic DNA binding domain and two alpha helices separated by a loop, typical of a transcription factor belonging to the MYC sub family of bHLH genes. Therefore, AMS plays a crucial role in tapetal cell development and the post-meiotic transcriptional regulation of microspore development within the developing anther.
authors.affiliation: Department of Molecular Plant Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany. sorensen@mpiz-koeln.mpg.de
authors.forename: Anna-Marie
authors.initials: AM
authors.lastname: Sorensen
authors.forename: Sandra
authors.initials: S
authors.lastname: Kröber
authors.forename: Ulrike S
authors.initials: US
authors.lastname: Unte
authors.forename: Peter
authors.initials: P
authors.lastname: Huijser
authors.forename: Koen
authors.initials: K
authors.lastname: Dekker
authors.forename: Heinz
authors.initials: H
authors.lastname: Saedler
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000235:genetics; D005091:Exons / Q000235:genetics; D020869:Gene Expression Profiling; D005816:Genetic Complementation Test; D018257:Helix-Loop-Helix Motifs; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000737:chemistry*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004269:DNA, Bacterial; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D014157:Transcription Factors; C480845:AMS protein, Arabidopsis; C036483:T-DNA