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Plants 2014, 3(1), 27-57; doi:10.3390/plants3010027
Article

Increasing Phosphatidylinositol (4,5)-Bisphosphate Biosynthesis Affects Basal Signaling and Chloroplast Metabolism in Arabidopsis thaliana

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Received: 4 November 2013; in revised form: 18 December 2013 / Accepted: 20 December 2013 / Published: 3 January 2014
(This article belongs to the Special Issue Plant Light Signalling)
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Abstract: One challenge in studying the second messenger inositol(1,4,5)-trisphosphate (InsP3) is that it is present in very low amounts and increases only transiently in response to stimuli. To identify events downstream of InsP3, we generated transgenic plants constitutively expressing the high specific activity, human phosphatidylinositol 4-phosphate 5-kinase Iα (HsPIPKIα). PIP5K is the enzyme that synthesizes phosphatidylinositol (4,5)-bisphosphate (PtdIns(4,5)P2); this reaction is flux limiting in InsP3 biosynthesis in plants. Plasma membranes from transgenic Arabidopsis expressing HsPIPKIα had 2–3 fold higher PIP5K specific activity, and basal InsP3 levels in seedlings and leaves were >2-fold higher than wild type. Although there was no significant difference in photosynthetic electron transport, HsPIPKIα plants had significantly higher starch (2–4 fold) and 20% higher anthocyanin compared to controls. Starch content was higher both during the day and at the end of dark period. In addition, transcripts of genes involved in starch metabolism such as SEX1 (glucan water dikinase) and SEX4 (phosphoglucan phosphatase), DBE (debranching enzyme), MEX1 (maltose transporter), APL3 (ADP-glucose pyrophosphorylase) and glucose-6-phosphate transporter (Glc6PT) were up-regulated in the HsPIPKIα plants. Our results reveal that increasing the phosphoinositide (PI) pathway affects chloroplast carbon metabolism and suggest that InsP3 is one component of an inter-organelle signaling network regulating chloroplast metabolism.
Keywords: phosphoinositide; inositol trisphosphate; phosphatidylinositol phosphate kinase; chloroplast; starch; carbon metabolism; photosynthesis; calcium; Arabidopsis phosphoinositide; inositol trisphosphate; phosphatidylinositol phosphate kinase; chloroplast; starch; carbon metabolism; photosynthesis; calcium; Arabidopsis
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Im, Y.J.; Smith, C.M.; Phillippy, B.Q.; Strand, D.; Kramer, D.M.; Grunden, A.M.; Boss, W.F. Increasing Phosphatidylinositol (4,5)-Bisphosphate Biosynthesis Affects Basal Signaling and Chloroplast Metabolism in Arabidopsis thaliana. Plants 2014, 3, 27-57.

AMA Style

Im YJ, Smith CM, Phillippy BQ, Strand D, Kramer DM, Grunden AM, Boss WF. Increasing Phosphatidylinositol (4,5)-Bisphosphate Biosynthesis Affects Basal Signaling and Chloroplast Metabolism in Arabidopsis thaliana. Plants. 2014; 3(1):27-57.

Chicago/Turabian Style

Im, Yang J.; Smith, Caroline M.; Phillippy, Brian Q.; Strand, Deserah; Kramer, David M.; Grunden, Amy M.; Boss, Wendy F. 2014. "Increasing Phosphatidylinositol (4,5)-Bisphosphate Biosynthesis Affects Basal Signaling and Chloroplast Metabolism in Arabidopsis thaliana." Plants 3, no. 1: 27-57.


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