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J Exp Bot. 2015 Nov;66(21):6905-16. doi: 10.1093/jxb/erv394. Epub 2015 Aug 12.

SQUINT promotes stem cell homeostasis and floral meristem termination in Arabidopsis through APETALA2 and CLAVATA signalling.

Author information

1
Laboratoire de Reproduction et Développement des Plantes, Université de Lyon1, CNRS, INRA, ENS-Lyon, 46 allée d'Italie, F-69364 Lyon cedex 07, France Department of Biological Sciences, Class of 1978 Life Sciences Center, 78 North College Street, Dartmouth College, Hanover NH 03755, USA.
2
Laboratoire de Reproduction et Développement des Plantes, Université de Lyon1, CNRS, INRA, ENS-Lyon, 46 allée d'Italie, F-69364 Lyon cedex 07, France.
3
Department of Biological Sciences, Class of 1978 Life Sciences Center, 78 North College Street, Dartmouth College, Hanover NH 03755, USA.
4
Laboratoire de Reproduction et Développement des Plantes, Université de Lyon1, CNRS, INRA, ENS-Lyon, 46 allée d'Italie, F-69364 Lyon cedex 07, France ctrehin@ens-lyon.fr.

Abstract

Plant meristems harbour stem cells, which allow for the continuous production of new organs. Here, an analysis of the role of SQUINT (SQN) in stem cell dynamics in Arabidopsis is reported. A close examination of sqn mutants reveals defects that are very similar to that of weak clavata (clv) mutants, both in the flower meristem (increased number of floral organs, occasional delay in stem cell termination) and in the shoot apical meristem (meristem and central zone enlargement, occasional fasciation). sqn has a very mild effect in a clv mutant background, suggesting that SQN and the CLV genes act in the same genetic pathway. Accordingly, a loss-of-function allele of SQN strongly rescues the meristem abortion phenotype of plants that overexpress CLV3. Altogether, these data suggest that SQN is necessary for proper CLV signalling. SQN was shown to be required for normal accumulation of various miRNAs, including miR172. One of the targets of miR172, APETALA2 (AP2), antagonizes CLV signalling. The ap2-2 mutation strongly suppresses the meristem phenotypes of sqn, indicating that the effect of SQN on stem cell dynamics is largely, but not fully, mediated by the miR172/AP2 tandem. This study refines understanding of the intricate genetic networks that control both stem cell homeostasis and floral stem cell termination, two processes that are critical for the proper development and fertility of the plant.

KEYWORDS:

APETALA2; CLAVATA signalling; SQUINT; floral meristem termination; flower development; stem cell homeostasis.

PMID:
26269626
DOI:
10.1093/jxb/erv394
[Indexed for MEDLINE]

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