Degeneration of photosynthetic capacity in mixotrophic plants, Chimaphila japonica and Pyrola decorata (Ericaceae)  

作　　者：Jiaojun Yu Chaobo Wang Xun Gong 

机构地区：[1]Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, PR China [2]Yunnan Key Laboratory for wild plant Resources, Kunming 650201, PR China [3]Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Kunming, PR China

出　　处：《Plant Diversity》2017年第2期80-88,共9页植物多样性（英文版）

摘　　要：The evolution of photosynthesis is an important feature of mixotrophic plants.Previous inferences proposed that mixotrophic taxa tend to retain most genes relating to photosynthetic functions but vary in plastid gene content.However,no sequence data are available to test this hypothesis in Ericaceae.To investigate changes in plastid genomes that may result from a transition from autotrophy to mixotrophy,the plastomes of two mixotrophic plants,Pyrola decorata and Chimaphila japonica,were sequenced at Illumina's Genome Analyzer and compared to the published plastome of the autotrophic plant Rhododendron simsii,which also belongs to Ericaceae.The greatest discrepancy between mixotrophic and autotrophic plants was that ndh genes for both P.decorata and C.japonica plastomes have nearly all become pseudogenes.P.decorata and C.japonica also retained all genes directly involved in photosynthesis under strong selection.The calculated rate of nonsynonymous nucleotide substitutions and synonymous substitutions of protein-coding genes(dN/dS) showed that substitution rates in shade plants were apparently higher than those in sunlight plants.The two mixotrophic plastomes were generally very similar to that of non-parasitic plants,although ndh genes were largely pseudogenized.Photosynthesis genes under strong selection were retained in the two mixotrophs,however,with greatly increased substitution rates.Further research is needed to gain a clearer understanding of the evolution of autotrophy and mixotrophy in Ericaceae.The evolution of photosynthesis is an important feature of mixotrophic plants. Previous inferences proposed that mixotrophic taxa tend to retain most genes relating to photosynthetic functions but vary in piastid gene content. However, no sequence data are available to test this hypothesis in Ericaceae. To investigate changes in plastid genomes that may result from a transition from autotrophy to mixotrophy, the plastomes of two mixotropbic plants, Pyrola decorata and Chimaphila japonica, were sequenced at lllumina＇s Genome Analyzer and compared to the published plastome of the autotrophic plant Rhodo- dendron simsii, which also belongs to Ericaceae. The greatest discrepancy between mixotrophic and autotrophic plants was that ndh genes for both P. decorata and C. japonica plastomes have nearly all become pseudogenes. P. decorata and C. japonica also retained all genes directly involved in photosyn- thesis under strong selection. The calculated rate of nonsynonymous nucleotide substitutions and syn- onymous substitutions of protein-coding genes （dN/dS） showed that substitution rates in shade plants were apparently higher than those in sunlight plants. The two mixotrophic plastomes were generally very similar to that of non-parasitic plants, although ndh genes were largely pseudogenized. Photo- synthesis genes under strong selection were retained in the two mixotrophs, however, with greatly increased substitution rates. Further research is needed to gain a clearer understanding of the evolution of autotrophy and mixotrophy in Ericaceae.

关 键 词：Chimaphila japonica Pyrola decorata Mixotroph Plastid genome 

分 类 号：Q945.11[生物学—植物学]