中文摘要：

稻属AA型物种包含栽培稻和与其最近缘的野生稻物种，是稻属植物中一个重要的类群．为了探究稻属AA型物种叶绿体基因组的适应性进化，以AA型稻属物种中已经公布的6个叶绿体基因组为对象，利用PAML和Selecton对叶绿体基因进行适应性进化的分析．研究发现，4个基因（matK，ccsA，psbB和rpoC2）经历了正选择作用，并对基因的正选择位点进行了定位，初步分析了正选择位点的变异特点，探讨了正选择位点与蛋白质结构保守性的关系．本研究为深入了解稻属的叶绿体基因及其适应性进化提供了重要参考．

英文摘要：

AA-genome species include cultivated Oryza species and closely related wild species, which form an important group in the genus Oryza, and now six chloroplast genornes in this group have been reported. To learn more about the adaptive evolution of the chloroplast genome in AA-genome Oryza species, we used PAML and Selecton to analyze these six chloroplast genomes. In this study, we detected four genes （matK, ccsA, psbB and rpoC2） under positive selection. We identified the positive-selected sites in each protein and analyzed the characteristics of these sites. We also discuss the influence of positive-selected sites on protein structure conservation. Our findings provide valuable clues for understanding the adaptive evolution of rice chloroplast genes.