Abstract
BackgroundThe Arabidopsis AtMYB80 transcription factor regulates genes involved in pollen development and controls the timing of tapetal programmed cell death (PCD). Downregulation of AtMYB80 expression precedes tapetal degradation. Inhibition of AtMYB80 expression results in complete male sterility. Full-length AtMYB80 homologs have been isolated in wheat, rice, barley and canola (C genome).ResultsThe complete sequences of MYB80 genes from the Brassica. napus (A gene), B. juncea (A gene), B. oleracea (C gene) and the two orthologs from cotton (Gossypium hirsutum) were determined. The deduced amino acid sequences possess a highly conserved MYB domain, 44-amino acid region and 18-amino acid C-terminal sequence. The cotton MYB80 protein can fully restore fertility of the atmyb80 mutant, while removal of the 44 amino acid sequence abolishes its function. Two conserved MYB cis-elements in the AtMYB80 promoter are required for downregulation of MYB80 expression in anthers, apparently via negative auto-regulation. In cotton, tapetal degradation occurs at a slightly earlier stage of anther development than in Arabidopsis, consistent with an earlier increase and subsequent downregulation in GhMYB80 expression. The MYB80 homologs fused with the EAR repressor motif have been shown to induce male sterility in Arabidopsis. Constructs were designed to maximize the level of male sterility.ConclusionsMYB80 genes are conserved in structure and function in all monocot and dicot species so far examined. Expression patterns of MYB80 in these species are also highly similar. The reversible male sterility system developed in Arabidopsis by manipulating MYB80 expression should be applicable to all major crops.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0278-3) contains supplementary material, which is available to authorized users.
Highlights
The Arabidopsis AtMYB80 transcription factor regulates genes involved in pollen development and controls the timing of tapetal programmed cell death (PCD)
The nucleotide sequences and the deduced amino acid sequences were compared with Arabidopsis AtMYB80 [1], B. napus MYB80 (C gene)
The results indicate that a combination of a strong promoter and a single copy of the ERF-associated amphiphilic repression (EAR) sequence fused to the MYB80MD protein will induce high levels of complete male sterility
Summary
The Arabidopsis AtMYB80 transcription factor regulates genes involved in pollen development and controls the timing of tapetal programmed cell death (PCD). The AtMYB80 transcription factor is involved in tapetum and pollen development and is required for the regulation of tapetal programmed cell death (PCD) in developing Arabidopsis anthers [1,2,3]. Three genes directly regulated by AtMYB80 have been identified using ChIP analysis, The AtMYB80 homologs from rice (Oryza sativa), wheat (Triticum aestivum), barley (Hordeum vulgare) and canola (Brassica napus) have been isolated and their protein sequences show significant conservation [6]. The expression patterns driven by the OsMYB80, TaMYB80 and BnMYB80 promoters in Arabidopsis are similar to that of AtMYB80, being restricted to the tapetum and developing microspores and occurring from stages 6 to 10. When driven by the AtMYB80 or their native promoters, the full-length OsMYB80, TaMYB80 and
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