Project description:Plastid phylogenomics clarifies broad-level relationships in Bulbophyllum (Orchidaceae) and provides insights into range evolution of Australasian section Adelopetalum.
Project description:A new species, Bulbophyllum papuaense, was described and illustrated from Indonesia. Bulbophyllum papuaense is similar to Bulbophyllum tortuosum and B. muscohaerens but differs from them by having rhizome and pseudobulbs covered with papillose scales, caudate and ciliate petals, linear and ciliate lip.
Project description:BackgroundBecause chloroplast (cp) genome has more conserved structures than nuclear genome and mitochondrial genome, it is a useful tool in estimating the phylogenetic relationships of plants. With a series of researches for cp genomes, there have been comprehensive understandings about the cp genome features. The genus Bulbophyllum widely distributed in Asia, South America, Australia and other places. Therefore, it is an excellent type genus for studying the effects of geographic isolation.ResultsIn this study, the cp genomes of nine Bulbophyllum orchids were newly sequenced and assembled using the next-generation sequencing technology. Based on 19 Asian (AN) and eight South American (SA) Bulbophyllum orchids, the cp genome features of AN clade and SA clade were compared. Comparative analysis showed that there were considerable differences in overall cp genome features between two clades in three aspects, including basic cp genome features, SSC/IRB junctions (JSBs) and mutational hotspots. The phylogenetic analysis and divergence time estimation results showed that the AN clade has diverged from the SA clade in the late Oligocene (21.50-30.12 mya). After estimating the occurrence rates of the insertions and deletions (InDels), we found that the change trends of cp genome structures between two clades were different under geographic isolation. Finally, we compared selective pressures on cp genes and found that long-term geographic isolation made AN and SA Bulbophyllum cp genes evolved variably.ConclusionThe results revealed that the overall structural characteristics of Bulbophyllum cp genomes diverged during the long-term geographic isolation, and the crassulacean acid metabolism (CAM) pathway may play an important role in the Bulbophyllum species evolution.
Project description:Pantropical Bulbophyllum, with ∼2,200 species, is one of the largest genera in Orchidaceae. Although phylogenetics and taxonomy of the ∼60 American species in the genus are generally well understood, some species complexes need more study to clearly delimit their component species and provide information about their evolutionary history. Previous research has suggested that the plastid genome includes phylogenetic markers capable of providing resolution at low taxonomic levels, and thus it could be an effective tool if these divergent regions can be identified. In this study, we sequenced the complete plastid genome of eight Bulbophyllum species, representing five of six Neotropical taxonomic sections. All plastomes conserve the typical quadripartite structure, and, although the general structure of plastid genomes is conserved, differences in ndh-gene composition and total length were detected. Total length was determined by contraction and expansion of the small single-copy region, a result of an independent loss of the seven ndh genes. Selection analyses indicated that protein-coding genes were generally well conserved, but in four genes, we identified 95 putative sites under positive selection. Furthermore, a total of 54 polymorphic simple sequence repeats were identified, for which we developed amplification primers. In addition, we propose 10 regions with potential to improve phylogenetic analyses of Neotropical Bulbophyllum species.
Project description:The complete plastid genome of Bulbophyllum pingnanense, a critically endangered species, was determined and analyzed in this study. The complete genome was 151,224 bp in length, consisting of a large single-copy region (LSC) of 86,017 bp, a small single-copy region (SSC) of 13,497 bp, and two inverted repeat (IR) regions of 25,855 bp. The genome contained 127 genes, including 81 protein-coding genes, 38 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. Phylogenetic analysis indicated that B. pingnanense is sister to B. inconspicuum.
Project description:A new orchid species, Bulbophyllum pingnanense, is described and illustrated from Fujian, China. It is similar to Bulbophyllum brevipedunculatum and Bulbophyllum albociliatum in vegetative and floral morphology, but it can be distinguished from Bulbophyllum brevipedunculatum by having a longer dorsal sepal with longer white ciliate on margin, longer and lanceolate lateral sepals, and a glabrous lip. It can be distinguished from Bulbophyllum albociliatum by having a shorter inflorescence, and a longer dorsal sepal.