Antagonistic Regulation of Flowering Time through Distinct Regulatory
Subunits of Protein Phosphatase 2A |
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Authors: | Behzad Heidari Dugassa Nemie-Feyissa Saijaliisa Kangasj?rvi Cathrine Lillo |
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Institution: | 1. University of Stavanger, Centre for Organelle Research, Faculty of
Science and Technology, Stavanger, Norway.; 2. Molecular Plant Biology, Department of Biochemistry and Food Chemistry,
University of Turku, Turku, Finland.; University of Nottingham, United Kingdom, |
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Abstract: | Protein phosphatase 2A (PP2A) consists of three types of subunits: a catalytic
(C), a scaffolding (A), and a regulatory (B) subunit. In Arabidopsis
thaliana and other organisms the regulatory B
subunits are divided into at least three non-related groups, B55, B’ and B″.
Flowering time in plants mutated in B55 or B''
genes were investigated in this work. The PP2A-b55α and
PP2A-b55β (knockout) lines showed earlier flowering than
WT, whereas a PP2A-b’γ (knockdown) line showed late flowering.
Average advancements of flowering in PP2A-b55 mutants were 3.4
days in continuous light, 6.6 days in 12 h days, and 8.2 days in 8 h days.
Average delays in the PP2A-b’γ mutant line were 7.1 days in 16
h days and 4.7 days in 8 h days. Expression of marker genes of genetically
distinct flowering pathways (CO, FLC, MYB33, SPL3), and the
floral integrator (FT, SOC1) were tested in WT, pp2a mutants,
and two known flowering time mutants elf6 and
edm2. The results are compatible with B55 acting at and/or
downstream of the floral integrator, in a non-identified pathway. B’
γ was involved in repression of FLC, the main
flowering repressor gene. For B’γ the results are consistent
with the subunit being a component in the major autonomous flowering pathway. In
conclusion PP2A is both a positive and negative regulator of flowering time,
depending on the type of regulatory subunit involved. |
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