comparative analysis of gene content evolution in phytoplasmas and mycoplasmas内容比较分析的基因进化phytoplasmas和支原体.pdf

Comparative Analysis of Gene Content Evolution in Phytoplasmas and Mycoplasmas 1. 1. 2 1 Ling-Ling Chen , Wan-Chia Chung , Chan-Pin Lin , Chih-Horng Kuo * 1 Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, 2 Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, Taiwan Abstract Phytoplasmas and mycoplasmas are two groups of important pathogens in the bacterial class Mollicutes. Because of their economical and clinical importance, these obligate pathogens have attracted much research attention. However, difficulties involved in the empirical study of these bacteria, particularly the fact that phytoplasmas have not yet been successfully cultivated outside of their hosts despite decades of attempts, have greatly hampered research progress. With the rapid advancements in genome sequencing, comparative genome analysis provides a new approach to facilitate our understanding of these bacteria. In this study, our main focus is to investigate the evolution of gene content in phytoplasmas, mycoplasmas, and their common ancestor. By using a phylogenetic framework for comparative analysis of 12 complete genome sequences, we characterized the putative gains and losses of genes in these obligate parasites. Our results demonstrated that the degradation of metabolic capacities in these bacteria has occurred predominantly in the common ancestor of Mollicutes, prior to the evolutionary split of phytoplasmas and mycoplasmas. Furthermore, we identified a list of genes that are acquired by the common ancestor of phytoplasmas and are conserved across all strains with compl