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Summary Abscission is predetermined in specialized cell layers called the abscission zone (AZ) and activated by developmental or environmental signals. In the grass family, most identified AZ genes regulate AZ anatomy, which differs among lineages. A YABBY transcription factor,SHATTERING1(SH1), is a domestication gene regulating abscission in multiple cereals, including rice andSetaria. In rice,SH1inhibits lignification specifically in the AZ. However, the AZ ofSetariais nonlignified throughout, raising the question of howSH1functions in species without lignification.Crispr‐Cas9 knockout mutants ofSH1were generated inSetaria viridisand characterized with histology, cell wall and auxin immunofluorescence, transmission electron microscopy, hormonal treatment and RNA‐Seq analysis.Thesh1mutant lacks shattering, as expected. No differences in cell anatomy or cell wall components including lignin were observed betweensh1and the wild‐type (WT) until abscission occurs. Chloroplasts degenerated in the AZ of WT before abscission, but degeneration was suppressed by auxin treatment. Auxin distribution and expression of auxin‐related genes differed between WT andsh1, with the signal of an antibody to auxin detected in thesh1chloroplast.SH1inSetariais required for activation of abscission through auxin signaling, which is not reported in other grass species.
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The leaf polarity factors SGS3 and YABBYs regulate style elongation through auxin signaling in Mimulus lewisii
Summary Style length is a major determinant of breeding strategies in flowering plants and can vary dramatically between and within species. However, little is known about the genetic and developmental control of style elongation.We characterized the role of two classes of leaf adaxial–abaxial polarity factors, SUPPRESSOR OF GENE SILENCING3 (SGS3) and the YABBY family transcription factors, in the regulation of style elongation inMimulus lewisii. We also examined the spatiotemporal patterns of auxin response during style development.Loss ofSGS3function led to reduced style length via limiting cell division, and downregulation ofYABBYgenes by RNA interference resulted in shorter styles by decreasing both cell division and cell elongation. We discovered an auxin response minimum between the stigma and ovary during the early stages of pistil development that marks style differentiation. Subsequent redistribution of auxin response to this region was correlated with style elongation. Auxin response was substantially altered when bothSGS3andYABBYfunctions were disrupted.We suggest that auxin signaling plays a central role in style elongation and that the way in which auxin signaling controls the different cell division and elongation patterns underpinning natural style length variation is a major question for future research.
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- Award ID(s):
- 1755373
- PAR ID:
- 10359975
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 232
- Issue:
- 5
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- p. 2191-2206
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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