Cloning of Agnp-G3 PDH gene from three cultivars of Apium graveolens and its sequence and expression characteristic analyses

Non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase gene Agnp-G3 PDH was cloned from cultivars ‘Liuhe Huangxinqin’ , ‘Jinnan Shiqin’ and ‘Ventura’ of Apium graveolens Linn., respectively. The sequence of Agnp-G3PDH gene from three cultivars contains an open reading frame ( ORF) with the full length of 1 491 bp, which encodes 496 amino acids. There are 84 base site differences, leading to site changes of 14 amino acids. Theoretical relative molecular mass of protein encoded by Agnp-G3 PDH gene from‘Liuhe Huangxinqin’ ,‘Jinnan Shiqin’ and‘Ventura’ is 53 201 . 6 , 53 051. 4 and 52 960. 3, respectively, and theoretical isoelectric point is pI 7. 49, pI 7. 86 and pI 8. 12,respectively. The number of basic amino acids is more than that of acidic amino acids in amino acid composition. And the proteins all possess double characteristics of hydrophilicity and hydrophobicity and all are the hydrophobic protein. The alignment result shows that homology of amino acid sequences encoded by Agnp-G3PDH gene from three cultivars reaches 99. 09%, which is highly conserved. Similarity of amino acid sequence among three cultivars and other eleven species is higher. Based on phylogenetic tree of amino acid sequence encoded by np-G3PDH gene, three cultivars are clustered in the same branch, and three cultivars and Populus trichocarpa Torr. & Gray in Salicaceae can be clustered together which shows that their np-G3PDH amino acid sequences have a closer evolutionary relationship. The result of quantitative real-time PCR shows that there are obvious differences in relative expression level of Agnp-G3PDH gene among different tissues of three cultivars, in which, relative expression level of the gene is the highest in leaf of ‘Jinnan Shiqin ’ , in flower of ‘Ventura ’ and in root of ‘Liuhe Huangxinqin’ . After treated by stress of high temperature (38℃) , low temperature (4℃) and drought (20%PEG), relative expression level of Agnp-G3PDH gene from three cultivars is extremely significantly higher or lower than that of the control, but after treated by salinity (0. 2 mol·L-1 NaCl) stress only that of ‘Jinnan Shiqin’ is significantly higher than that of the control, and that of ‘Liuhe Huangxinqin’ and‘Ventura’ has no significant difference with that of the control. It is indicated that the expression of Agnp-G3PDH gene has tissue specificity and is related to resistance difference among cultivars.