Regulation of Arabidopsis tapetum development and function by DYSFUNCTIONAL TAPETUM1 (DYT1) encoding a putative bHLH transcription factor.
In flowering plants, male fertility depends on proper cell differentiation in the anther. However, relatively little is known about the genes that regulate anther cell differentiation and function. Here, we report the analysis of a new Arabidopsis male sterile mutant, dysfunctional tapetum1 (dyt1). The dyt1 mutant exhibits abnormal anther morphology beginning at anther stage 4, with tapetal cells that have excess and/or enlarged vacuoles and lack the densely stained cytoplasm typical of normal tapetal cells. The mutant meiocytes are able to complete meiosis I, but they do not have a thick callose wall; they often fail to complete meiotic cytokinesis and eventually collapse. DYT1 encodes a putative bHLH transcription factor and is strongly expressed in the tapetum from late anther stage 5 to early stage 6, and at a lower level in meiocytes. In addition, the level of DYT1 mRNA is reduced in the sporocyteless/nozzle (spl/nzz) and excess microsporocytes1/extra sporogenous cell (ems1/exs) mutants; together with the mutant phenotypes, this suggests that DYT1 acts downstream of SPL/NZZ and EMS1/EXS. RT-PCR results showed that the expression levels of many tapetum-preferential genes are reduced significantly in the dyt1 mutant, indicating that DYT1 is important for the expression of tapetum genes. Our results support the hypothesis that DYT1 is a crucial component of a genetic network that controls anther development and function.
Zhang
Wei
W
Department of Biology and the Huck Institutes of Life Sciences, the Pennsylvania State University, University Park, PA 16802, USA.
Sun
Yujin
Y
Timofejeva
Ljudmilla
L
Chen
Changbin
C
Grossniklaus
Ueli
U
Ma
Hong
H
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051792:Basic Helix-Loop-Helix Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017124:Conserved Sequence; D005298:Fertility / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D018257:Helix-Loop-Helix Motifs; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D010641:Phenotype; D011494:Protein Kinases / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D009687:Nuclear Proteins; D011494:Protein Kinases; D012097:Repressor Proteins; D014157:Transcription Factors; C514534:DYT1 protein, Arabidopsis; C416221:SPL protein, Arabidopsis; C464786:At5g07280 protein, Arabidopsis