Codon bias patterns in photosynthetic genes of halophytic grass Aeluropus littoralis

Codon bias refers to the differences in the frequency of occurrence of synonymous codons in codingdna. pattern of codon and optimum codon utilization is significantly different between the lives. thisdifference is due to the long term function of natural selection and evolution process. genetics drift,mutation and regulation of gene expression are the main reasons for codon bias. in this study, the codonbias analysis was done on photosynthesis and respiratory related genes of phosphoenolpyruvatecarboxylase (pepc), nadp-malic enzyme (nadp-me), pyruvate orthophosphate dikinase (ppdk),glycerate kinase (gk) (nuclear genes), rubisco, nadh-dehydrogenase subunit f and cytochrome-c(chloroplast genes) from aeluropus littoralis plant. nuclear gene sequences were obtained after partialisolation and for chloroplast genes obtained from nucleotide database. calculation of codon adaptationindex (cai) showed that studied genes with direct or indirect association with photosynthesis, had highlevel of gene expression and had also a tendency to optimum codon utilization. the results also showedthe difference in codon bias between genes encoded in nucleus and chloroplast for some amino acids.