Dissection of Arabidopsis NCED9 promoter regulatory regions reveals a role for ABA synthesized in embryos in the regulation of GA-dependent seed germination

Published Date

May 2016, Vol.246:91–97, doi:10.1016/j.plantsci.2016.02.013

Title 

Dissection of Arabidopsis NCED9 promoter regulatory regions reveals a role for ABA synthesized in embryos in the regulation of GA-dependent seed germination

• Author 

• Mitsunori Seo ^a,b,,
• Yuri Kanno ^a
• Anne Frey ^b
• Helen M. North ^b
• Annie Marion-Poll ^b,,

• aRIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan
• bInstitut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, RD10, 78026 Versailles Cedex, France

Received 18 December 2015. Revised 12 February 2016. Accepted 13 February 2016. Available online 16 February 2016.

Highlights

• •
  We identified promoter regions required for the NCED9 expression in testa and embryos during seed develioment in Arabidopsis.
• •
  Several homeodomain-leucine zipper (HD-Zip) proteins ATHBs bound to a sequence required for the NCED9 expression in testa.
• •
  ABA synthesized in embryos mediated by NCED9 regulates GA-dependent seed germination.

Abstract

Nine-cis-epoxycarotenoid dioxygenase (NCED) catalyzes the key step of abscisic acid (ABA) biosynthesis. There are five genes encoding NCED in Arabidopsis, which differentially regulate ABA biosynthesis in a spatiotemporal manner in response to endogenous and environmental stimuli. Previous studies have shown that NCED9 is expressed in testa and embryos during seed development. In the present study, we have identified promoter regions required for the expression of NCED9 in testa and embryos, respectively. Electrophoretic mobility shift assays (EMSA) and yeast one-hybrid (Y1H) assays showed that several homeodomain-leucine zipper (HD-Zip) proteins, namely ATHBs, bound to the sequence required for expression of NCED9 in testa, suggesting that they redundantly regulate NCED9 expression. By expressing the NCED9 gene under the control of a deleted NCED9 promoter in an nced9 mutant expression was limited to embryos. Transformants were complemented for the paclobutrazol resistant germination phenotype of the mutant, suggesting that the ABA synthesis mediated by NCED9 in embryos plays an important role in the regulation of gibberellin (GA)-dependent seed germination.

Keywords

• Abscisic acid (ABA)
• Arabidopsis
• ATHB
• Nine-cis-epoxycarotenoid dioxygenase (NCED)
• Promoter
• Seed germination

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• ⁎ 
  Corresponding author at: RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
• ⁎⁎ 
  Corresponding author at: Institut Jean-Pierre Bourgin, UMR 1318 INRA-AgroParisTech, INRA Centre de Versailles-Grignon, Bâtiment 2, Route de Saint Cyr, 78026 Versailles Cedex, France.

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