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

Plants

Yang Ju Im²  Caroline M. Smith²  Brian Q. Phillippy²  Deserah Strand¹  David M. Kramer¹  Amy M. Grunden² 

[1] DOE-Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA; E-Mails:;Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA; E-Mails:

关键词: phosphoinositide;    inositol trisphosphate;    phosphatidylinositol phosphate kinase;    chloroplast;    starch;    carbon metabolism;    photosynthesis;    calcium;    Arabidopsis;   

DOI  :  10.3390/plants3010027

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.