The Arabidopsis MALE STERILITY1 (MS1) gene is a transcriptional regulator of male gametogenesis, with homology to the PHD‐finger family of transcription factors

Abstract

SummaryWe report here the molecular characterisation of the Arabidopsis MALE STERILITY1 gene, which is a critical sporophytic controlling factor for anther and pollen development. Homozygous ms1 mutants do not produce viable pollen, but are otherwise phenotypically normal. Degeneration of pollen occurs soon after microspore release from the tetrads, at which time the tapetum also appears abnormally vacuolated. The MS1 gene is expressed at low levels in anthers from closed buds, with expression in the tapetum at the stage of microspore release. No expression is seen in open¯owers. The deduced MS1 protein sequence shows strong homology to the PHD-®nger motif found in known transcription factors from humans, yeast and higher plants. Six alleles of ms1 have been identi®ed; all result in premature termination of the MS1 protein and loss of the PHD-®nger motif. MS1 is likely to play a key role in regulating transcription during speci®c stages of male gametogenesis and anther development. As such, MS1 provides a valuable tool for the manipulation of male sterility in higher plants.

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

“…9; Supplemental Data Set S2). PTC1 was located in the same clade with Arabidopsis MS1 (Wilson et al, 2001;Ito and Shinozaki, 2002;Ariizumi et al, 2005). In this clade, PTC1 homologs were encoded by a single subfamily member in rice, Sorghum bicolor, Arabidopsis, grape (Vitis vinifera), poplar (Populus trichocarpa), Ricinus communis, and Physcomitrella patens (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. Similarly, we also observed an elevated and prolonged expression level of PTC1 in the ptc1 mutant.…”

“…Tapetal cell development and differentiation are critical for the early events in male reproduction, including meiosis; however, during late pollen development, tapetal degeneration, triggered by an apoptosis-like process, is also vital for viable pollen formation (Papini et al, 1999;Varnier et al, 2005;Li et al, 2006;Aya et al, 2009). Currently, although several genes encoding putative transcription factors have been reported to be associated with tapetal function and degeneration, such as Arabidopsis (Arabidopsis thaliana) MYB33/MYB65 (Millar and Gubler, 2005), DYSFUNCTIONAL TAPETUM1 (DYT1; Zhang et al, 2006), ABORTED MICROSPORE (AMS; Sorensen et al, 2003;Xu et al, 2010), and MALE STERILITY1 (MS1; Wilson et al, 2001;Ito and Shinozaki, 2002) and rice (Oryza sativa) GAMYB (Kaneko et al, 2004;Aya et al, 2009;Liu et al, 2010), UNDEVELOPED TAPETUM1 (UDT1; Jung et al, 2005), TAPETUM DE-GENERATION RETARDATION (TDR; Li et al, 2006), and MADS3 (Hu et al, 2011), their detailed functional roles in regulating tapetal PCD during anther development are unclear. We have shown that the Arabidopsis ms1 mutant displays altered tapetal development, with a lack of normal PCD and abnormal tapetal degeneration associated with large autophagic vacuoles and mitochondrial swelling (Vizcay-Barrena and Wilson, 2006).…”

Global Expression Profiling Applied to the Analysis of Arabidopsis Stamen Development

“…Lastly, we analyzed the ms1 mutant to identify genes expressed during pollen development and maturation. To this end, we used the ms1-1 allele, which carries a mutation in a splice acceptor site (Wilson et al, 2001). For both ms1 and spl/nzz, as well as for the wild type, tissue samples containing the inflorescence meristem and floral buds up to stage 13 were collected for analysis.…”

“…In spl/nzz mutants, the nucellus and the pollen sac fail to form, indicating that SPL/NZZ, which encodes a putative transcription factor, plays a key role in the development of both male and female sporangia (Schiefthaler et al, 1999;Yang et al, 1999). ms1 mutants do not produce viable pollen but are otherwise phenotypically normal (Wilson et al, 2001;Ito and Shinozaki, 2002). In ms1 mutant plants, degeneration of pollen starts to occur after microspore release from the tetrads, at which time the surrounding tapetal cells appear abnormally vacuolated.…”