The sequential action of MIDA9/PP2C.D1, PP2C.D2, and PP2C.D5 is necessary to form and maintain the hook after germination in the dark
Author
Rovira, Arnau
Sentandreu, Maria
Nagatani, Akira
Leivar Rico, Pablo
Monte, Elena
Other authors
Universitat Ramon Llull. IQS
Publication date
2021-03-09ISSN
1664-462X
Abstract
During seedling etiolation after germination in the dark, seedlings have closed cotyledons and form an apical hook to protect the meristem as they break through the soil to reach the surface. Once in contact with light, the hook opens and cotyledons are oriented upward and separate. Hook development in the dark after seedling emergence from the seed follows three distinctly timed and sequential phases: formation, maintenance, and eventual opening. We previously identified MISREGULATED IN DARK9 (MIDA9) as a phytochrome interacting factor (PIF)-repressed gene in the dark necessary for hook development during etiolated growth. MIDA9 encodes the type 2C phosphatase PP2C.D1, and pp2c-d1/mida9 mutants exhibit open hooks in the dark. Recent evidence has described that PP2C.D1 and other PP2C.D members negatively regulate SMALL AUXIN UP RNA (SAUR)-mediated cell elongation. However, the fundamental question of the timing of PP2C.D1 action (and possibly other members of the PP2C.D family) during hook development remains to be addressed. Here, we show that PP2C.D1 is required immediately after germination to form the hook. pp2c.d1/mida9 shows reduced cell expansion in the outer layer of the hook and, therefore, does not establish the differential cell growth necessary for hook formation, indicating that PP2C.D1 is necessary to promote cell elongation during this early stage. Additionally, genetic analyses of single and high order mutants in PP2C.D1, PP2C.D2, and PP2C.D5 demonstrate that the three PP2C.Ds act collectively and sequentially during etiolation: whereas PP2C.D1 dominates hook formation, PP2C.D2 is necessary during the maintenance phase, and PP2C.D5 acts to prevent opening during the third phase together with PP2C.D1 and PP2C.D2. Finally, we uncover a possible connection of PP2C.D1 levels with ethylene physiology, which could help optimize hook formation during post-germinative growth in the dark.
Document Type
Article
Document version
Published version
Language
English
Subject (CDU)
5 - Natural Sciences
Keywords
Skotomorphogenesis
Etiolation
Hook
MIDA9
PP2C.D phosphatases
Phytochrome interacting factor PIF
Ethylene
Etilè
Germinació
Pages
12 p.
Publisher
Frontiers Media
Is part of
Frontiers in Plant Science
Grant agreement number
info:eu-repo/grantAgreement/Marie Curie/IRG PIRG06-GA-2009-256420
info:eu-repo/grantAgreement/MCIU i FEDER/PN I+D/BIO2009-07675
info:eu-repo/grantAgreement/MCIU i FEDER/PN I+D/BIO2015-68460-P
info:eu-repo/grantAgreement/MCIU i FEDER/PN I+D/PGC2018-099987-B-I00
info:eu-repo/grantAgreement/SUR del DEC/SGR/2009-SGR-206
info:eu-repo/grantAgreement/SUR del DEC/SGR/2017-SGR-718
info:eu-repo/grantAgreement/MINECO/Centro de Excelencia Severo Ochoa 2016–2019 Program/SEV-2015-0533
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Rights
© L'autor/a
Except where otherwise noted, this item's license is described as http://creativecommons.org/licenses/by/4.0/