Fuctional Characterization Of AtGDPD5 In Arabidopsis Thaliana Responses Of Pi Starvation

Glycerophosphodiester phosphodiesterase (EC 3.1.4.46, GDPD) hydrolyzes glyceropho-sphodiesters into sn-glycerol-3-phosphate and the corresponding alcohols in prokaryotes and non-plant eukaryotes, which may be a key member of enzymes in phospholipid catabolism pathway. To date, little is known about biochemical properties and physiological roles of GDPD proteins in plant growth and development.In this study, we characterized the GDPD gene family and analysed function of AtGDPD5 gene in low phosphorus environment. First, we classify the genes of GDPD family in arabidopsis. Second, we want to know this family's expression mode. Last, we intend to study how AtGDPD5 adaped to low-phosphate condition. Many results are presented as follow:We identified Arabidopsis GDPD gene family. Using the conserved GDPD domain of E. coli GlpQ (PF03009, Pfam), we found thirteen homologues with the GDPD domain in the Arabidopsis genome. According to the number of the GDPD domain and the similarity of the conserved sequence motif, the Arabidopsis GDPD family was classified into AtGDPD and AtGDPDL subfamilies.Northern analysis showed that all genes are expressed in flowers and siliques. Moreover, many genes such as AtGDPD3, AtGDPD6, AtGDPDL6 and AtGDPDL7 were specifically expressed in the flowers. It seemed that AtGDPDl was mainly expressed in the young seedling and rosette leaves while AtGDPD5 was relatively broadly expressed in various tissues. AtGDPDL1 and AtGDPDL2 were expressed mainly in the aboveground tissues while AtGDPDL3 was ubiquitously expressed.We found that the expression of Arabidopsis GDPD5 is induced by various environmental factors. Northern analysis showed that salt and osmotic stresses but not Pi starvation stimulated expression of AtGDPD5 genes in varying degrees. Promoter activity of AtGDPD5 gene was promoted by Pi starvation. Interestingly, sequence analysis of the AtGDPD5 gene promoters did reveal the presence of a cis-element bound to phosphate starvation response1 (PHR1) and PHO.AtGDPD5 plays important role in the growth of Arabdopsis under Pi starvation. Compared with the WT, the growth of atgdpd5-1 mutant under Pi starvation, is noticeably promoted, and its primary root length is longer than WT's. Additionally, Pi starvation strongly upregulated the total phosphorus content in atgdpd5-1 plants, while lower total phosphorus content in WT.