The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is inco...The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is incomplete,and phylogenetic relationships within the order Nymphaeales remain controversial.In this study,12 chloroplast genomes of Nymphaea were assembled and analyzed for the first time.These genomes were 158,290-160,042 bp in size and contained 113 non-repeat genes,including 79 protein-coding genes,30 tRNA genes,and four rRNA genes.We also report on codon usage,RNA editing sites,microsatellite structures,and new repetitive sequences in this genus.Comparative genomics revealed that expansion and contraction of IR regions can lead to changes in the gene numbers.Additionally,it was observed that the highly variable regions of the chloroplast genome were mainly located in intergenic regions.Furthermore,the phylogenetic tree showed the order Nymphaeales was divided into three families,and the genus Nymphaea can be divided into five(or three)subgenera,with the subgenus Nymphaea being the oldest.The divergence times of nymphaealean taxa were analyzed,with origins of the order Nymphaeales and family Nymphaeaceae being about 194 and 131 million years,respectively.The results of the phylo-genetic analysis and estimated divergence times will be useful for future evolutionary studies of basal angiosperm lineages.展开更多
基金supported by the National Natural Science Foundation of China(No.32370244)the Taishan Scholar Project(No.tsqn202306214)+1 种基金the Shandong Province Natural Science Foundation of China(No.ZR2023MC157)the State Key Laboratory of Pal-aeobiology and Stratigraphy(No.223123).
文摘The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is incomplete,and phylogenetic relationships within the order Nymphaeales remain controversial.In this study,12 chloroplast genomes of Nymphaea were assembled and analyzed for the first time.These genomes were 158,290-160,042 bp in size and contained 113 non-repeat genes,including 79 protein-coding genes,30 tRNA genes,and four rRNA genes.We also report on codon usage,RNA editing sites,microsatellite structures,and new repetitive sequences in this genus.Comparative genomics revealed that expansion and contraction of IR regions can lead to changes in the gene numbers.Additionally,it was observed that the highly variable regions of the chloroplast genome were mainly located in intergenic regions.Furthermore,the phylogenetic tree showed the order Nymphaeales was divided into three families,and the genus Nymphaea can be divided into five(or three)subgenera,with the subgenus Nymphaea being the oldest.The divergence times of nymphaealean taxa were analyzed,with origins of the order Nymphaeales and family Nymphaeaceae being about 194 and 131 million years,respectively.The results of the phylo-genetic analysis and estimated divergence times will be useful for future evolutionary studies of basal angiosperm lineages.
