Expression Profile Analysis Of Arabidopsis Phosphatidylinositol Signaling Pathway Relevant Genes And Function Characterization Of Arabidopsis Inositol Polyphosphate 5-phosphatase

Phosphatidyldinositol signal transduction pathway was critical in many plant developmental processes including gene expressions, cell responses to environmental factors, function of hormones. It is a complex signal network surrounding the important second messenger molecular IP3 and Ca2+-related signal in plant germination, growth, procreation, senescence, and responses. And previous studies have focused on the isolation and functional characterization of genes of multigene families of PI pathway (PLC route). Among them, PIPK, PLC, and 5PTase are all large families with more than ten members and suggesting their different expression patterns and physiological functions. For example, they expressed in the different tissues, cell types, development stages, and responses processes to distinguish environmental factors. In this thesis, we study the general conditions about expression patterns and functions of the whole pathway by cDNA chip technique. Total 79 mRNA clones in Arabidopsis genome has been collected to design special primers in N-terminal. PCR fragments were amplified for generation of cDNA chips and further expression profiling analysis under multiple developmental processes. Results showed that PI pathway-involved families and isoforms have specific expression patterns in different conditions, and the regulatory expressions illuminated their possibly involving almost all kinds of vital processes. Among this pathway, we pay attention to a large family of 5PTase which have been the major terminator of the IP3/Ca2+ signal. We search the Arabidopsis genome and find the 5PTase family which comprises 15 members. 5PTase proteins fall into two subtypes comprising polypeptides of 70 kD (type I) and more than 120 kD (type II), respectively. Sequence analysis showed that all predicted 5PTase proteins contain a high-conserved inositol polyphosphate phosphatase signature′within the predicted catalytic domain. Type II members possess multiple WD-40 repeats, indicating potential function in proteins interaction and related regulation. Full-length cDNAs encoding type II (At5pt13, 14,) and type I proteins (At5PTase4), respectively, were isolated. Comparison with other putative or isolated isoforms through out high similarities in nucleic acid and amino acid sequences in At5PTase family, especially in subtypes. Semi-quantitative RT-PCR and chips...