Cloning and functional analysis of the psbD gene in Pseudosasa japonica f. akebonosuji

Key words: 
• molecular biology /
• Pseudosasa japonica f. akebonosuji /
• psbD genes /
• cloning /
• leave color variation /
• quantitative real time-polymerase chain reaction （qRT-PCR）

Abstract: Photosystem Ⅱ （PSⅡ） of a plant chloroplast is an important protein complex in light-dependent reactions of oxygenic photosynthesis with the psbD gene encoding the center protein D2. Until now, psbD gene in Pseudosasa japonica f. akebonosuji still would not been sequenced and reported. In order to analysis the psbD gene structure and the potential relation of psbD gene function and leaf color variation, in this study the genomic DNA of Pseudosasa japonica f. akebonosuji was extracted and the full-length psbD gene sequence （Pj-psbD） was amplified by polymerase chain reaction （PCR）. The expression pattern for Pj-psbD was detected by the fluorescence quantitative PCR technique in three different growth （S1, S2 and S3） stages using green, stripe and albino leaves of P. japonica f. akebonosuji leaves with three material replicates and three expriements replicates. Results showed that the Open Reading Frame （ORF） of Pj-psbD was 1 059 bp long encoding 352 amino acids with a relative molecular weight of 39.59 kD and an isoelectric point of 5.34. In the Pj-psbD polypeptide chain, there were six transmembrane domains, plus multiple photosynthesis domains and other function sites. Among the three colors of leaves the psbD expression level in the three growth stages of the albino leaves was highest with more than 2－4 times than those of the according three growth stages of the green leaves. The continuously increasing expression levels of the gene along with leaf growth and development for the three types of leaves could meet the formation needs of the chloroplast, and the high psbD expression level in the albino leaf could be the protection mechanism that inhibits light damage in the photosynthetic system. ［Ch, 8 fig. 1 tab. 25 ref.］