Arabidopsis MALE STERILITY1 Encodes a PHD-Type Transcription Factor and Regulates Pollen and Tapetum Development

Abstract

The Arabidopsis thaliana MALE STERILITY1 (MS1) gene encodes a nuclear protein with Leu zipper-like and PHD-finger motifs and is important for postmeiotic pollen development. Here, we examined MS1 function using both cell biological and molecular biological approaches. We introduced a fusion construct of MS1 and a transcriptional repression domain (MS1-SRDX) into wildtype Arabidopsis, and the transgenic plants showed a semisterile phenotype similar to that of ms1. Since the repression domain can convert various kinds of transcriptional activators to dominant repressors, this suggested that MS1 functioned as a transcriptional activator. The Leu zipper-like region and the PHD motif were required for the MS1 function. Phenotypic analysis of the ms1 mutant and the MS1-SRDX transgenic Arabidopsis indicated that MS1 was involved in formation of pollen exine and pollen cytosolic components as well as tapetum development. Next, we searched for MS1 downstream genes by analyzing publicly available microarray data and identified 95 genes affected by MS1. Using a transgenic ms1 plant showing dexamethasoneinducible recovery of fertility, we further examined whether these genes were immediately downstream of MS1. From these results, we discuss a role of MS1 in pollen and tapetum development and the conservation of MS1 function in flowering plants.

PERSISTENT TAPETAL CELL1Encodes a PHD-Finger Protein That Is Required for Tapetal Cell Death and Pollen Development in Rice

“…Phylogenetic analysis indicates that Arabidopsis MS1, poplar PtMS1, and rice PTC1 form a separate group within the entire family (Ito et al, 2007), suggesting that PTC1 and its close homologs may have a conserved role in plant reproductive development. Consistent with this hypothesis, PTC1 driven by the MS1 promoter is able to rescue pollen wall development and pollen fertility of the homozygous ms1 mutant, suggesting a conserved role regulating programmed anther development in monocot and dicot species (Fig.…”

“…Also, neither ms1 (Ito et al, 2007) nor ptc1 could be rescued using the equivalent wild-type gene driven by the cauliflower mosaic virus 35S promoter, suggesting that the precise control of MS1/PTC1 expression is critical for pollen development. MS1 expression in the ms1 mutant shows increased expression (Wilson et al, 2001;Yang et al, 2007), suggesting that MS1 is able to negatively regulate its own expression.…”

Analysis of TETRAKETIDE α-PYRONE REDUCTASE Function in Arabidopsis thaliana Reveals a Previously Unknown, but Conserved, Biochemical Pathway in Sporopollenin Monomer Biosynthesis

“…Pollen wall formation requires exquisite and coordinated spatiotemporal regulation of numerous biosynthetic genes by specific transcriptional regulators (Alves-Ferreira et al, 2007;Ito et al, 2007;Yang et al, 2007). In particular, many genes involved in exine biosynthesis in Arabidopsis have been shown to be repressed by the MS1 transcription factor in wild-type plants and to be overexpressed in the ms1 mutant (Ito et al, 2007;Yang et al, 2007).…”

“…In particular, many genes involved in exine biosynthesis in Arabidopsis have been shown to be repressed by the MS1 transcription factor in wild-type plants and to be overexpressed in the ms1 mutant (Ito et al, 2007;Yang et al, 2007). Examination of Arabidopsis microarray data showed that, during development of wild-type and ms1 anthers, several uncharacterized genes are coregulated with genes involved in exine formation.…”

“…Significant progress in our understanding of exine formation processes has been made recently, thanks to genetic and molecular studies of Arabidopsis mutants exhibiting defects in exine structure and deposition (Aarts et al, 1997;PaxsonSowders et al, 2001;Ariizumi et al, 2003Ariizumi et al, , 2004Ito et al, 2007;Morant et al, 2007;Yang et al, 2007;Guan et al, 2008;Suzuki et al, 2008;de Azevedo Souza et al, 2009;Dobritsa et al, 2009a;Tang et al, 2009). Unfortunately, in most cases, annotations of the mutated Arabidopsis genes found to be responsible for pollen phenotypes are primarily based on sequence similarity, and the exact functions of the corresponding proteins in pollen development remain unknown.…”