Abstract
Background The shoot apical meristem (SAM) in plants is composed of a small mound of pluripotent stem cells that generate new organs. ARGONAUTE10 (AGO10) is known to be critical for maintenance of the embryonic SAM by regulating the expression of Class III HOMEODOMAIN-LEUCINE ZIPPER (HD-ZIP III) transcription factors, which then modulate downstream responses to the key phytohormone auxin. However, we do not understand how AGO10 modulates auxin responses after embryogenesis in the mature plant.
Results Here we show that AGO10 regulates auxin responses in the post-embryonic SAM via the bHLH transcription factor INDEHISCENT (IND). IND directly regulates auxin responses in the SAM regulating the auxin transporter PIN1 via direct transcriptional regulation of PINOID kinase. We show that a loss of function ind mutation significantly restores ago10zwl-3 mutant SAM and fruit phenotypes. ago10zwl-3 mutants overexpress IND and overexpression of IND phenocopies the ago10zwl-3 SAM phenotypes, and regulates auxin transport and responses in the SAM. AGO10 also regulates post-embryonic development in the fruit via a similar genetic pathway.
Conclusions We characterise a molecular mechanism that is conserved during post embryonic development linking AGO10 directly to auxin responses.
Competing Interest Statement
The authors have declared no competing interest.
Abbreviations
- SAM
- Shoot apical meristem
- AGO10zwl-3
- ZWILLE-3 in Ler background.
- AGO10-4
- AGO10-4 in Col background.
- IND
- INDEHISCENT
- SPT
- SPATULA
- YFP
- yellow fluorescent protein
- GFP
- green fluorescent protein
- Ler
- Landsberg erecta
- qRT-PCR
- quantitative reverse transcriptase polymerase chain reaction
- HD-ZIP III
- HOMEODOMAIN LEUCINE ZIPPER class III
- REV
- REVOLUTA
- PHB
- PHABULOSA
- PHV
- PHAVALUTA
- PID
- PINOID
- GUS
- beta-Glucuronidase
- DEX
- dexamethasone
- GR
- glucocorticoid receptor
- ChIP
- Chromatin immunoprecipitation
- NPA
- Naphthylphthalamic acid
- GSEA
- gene set enrichment analysis.