DNA-binding protein phosphatase AtDBP1 acts as a promoter of flowering in Arabidopsis
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We provide evidence that AtDBP1 promotes flowering by regulating the transcript levels of several important integrators and floral meristem identity genes, including FLC, CO, SOC1, LFY, FT and FD.
DNA-binding protein phosphatases (DBP) which exhibit both sequence specific DNA-binding and protein phosphatase 2C activities are important regulators that are involved in both the transcriptional and post-translational regulations. DBP factors are known to mediate susceptibility to potyviruses; however, whether they are involved in other processes is still unclear. In this study, under both long day (LD) and short day conditions, AtDBP1 overexpressing plants displayed early flowering, while the knock out mutants, atdbp1, exhibited a delay in flowering relative to the wild-type plants; both the overexpressing lines and atdbp1 mutants remained photoperiodic sensitive, indicating that AtDBP1 was involved in the autonomous pathway. AtDBP1 does not respond to vernalization at transcript level, and both AtDBP1 overexpressing plants and atdbp1 mutants remain responsive to vernalization, indicating that AtDBP1 may not be directly involved in vernalization. Real-time PCR analysis showed that AtDBP1 can suppress FLOWERING LOCUC C (FLC) expression, a key integrator of the autonomous and vernalization pathways, and enhance the expression levels of CONSTANS and FLOWERING LOCUC T, key regulators of the LD pathway. Furthermore, expression of floral meristem identity genes including SUPPRESSOR OF OVEREXPRESSION OF CO 1, LEAFY and FD was also promoted in AtDBP1overexpressing plants. AtDBP1 transcription can be detected in root, leaf, stem, flower and silique. AtDBP1–GFP and YFP–AtDBP1 fusion protein were localized in the cytosol and nucleus. Our results provide the evidence demonstrating the effective role of AtDBP1 for flowering time regulation and report a novel function of DBP factors in planta besides in plant defense.
KeywordsAutonomous pathway DBP factors FLOWERING LOCUC C Protein phosphatase 2C Vernalization pathway
DNA-binding protein phosphatases
Green fluorescent protein
Protein phosphatase 2C
Yellow fluorescent protein
We thank the NASC for providing mutant seeds used in this study and we would like to thank Ning Jiang from Michigan State University for language editing. This work was supported by National Natural Science Foundation of China [31471518, 31271742 and 31301338]; Chinese Academy of Sciences [Grant KZCX2-EW-303 and Hundred Talents Program, Grant XDA08010105]. Open Fund of Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences [2011ZKHT-05] and Heilongjiang Postdoctoral Grant [LBH-Z11232].
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