The Arabidopsis ABORTED MICROSPORES (AMS) gene encodes a MYC class transcription factor

• Published in: The Plant journal : for cell and molecular biology 2003-01, Vol.33 (2), p.413-423
• Main Authors: Sorensen, Anna‐Marie, Kröber, Sandra, Unte, Ulrike S., Huijser, Peter, Dekker, Koen, Saedler, Heinz
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arabidopsis - genetics; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Base Sequence; Basic Helix-Loop-Helix Transcription Factors; basic helix‐loop‐helix motif; Biological and medical sciences; Biology and morphogenesis of the reproductive apparatus. Photoperiodism, vernalisation; Chromosome Mapping; DNA, Bacterial - genetics; Exons - genetics; Fundamental and applied biological sciences. Psychology; gametogenesis; Gene Expression Profiling; Genetic Complementation Test; Helix-Loop-Helix Motifs; male sterility; microspore development; Molecular Sequence Data; Mutation - genetics; MYC family; Phenotype; Plant physiology and development; Plants, Genetically Modified; Promoter Regions, Genetic - genetics; Proto-Oncogene Proteins c-myc - chemistry; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Transcription Factors - chemistry; Transcription Factors - classification; Transcription Factors - genetics; Transcription Factors - metabolism; Vegetative and sexual reproduction, floral biology, fructification
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.2003.01644.x

Summary 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.