Phylogenetic relationships of Gelidocalamus Wen based on chloroplast gene segments
[Objective]Gelidocalamus Wen,a genus of bamboo plants,belongs to the tribe Arundinarieae in the subfamily Bambusoideae of the family Poaceae.It is a genus of scattered bamboo endemic to the subtropical regions of China.These plants are characterized by their shrubby woody stems,underground rhizomes in a complex axis,slender stems,branching at each node,with no secondary branches produced in the same year,typically one leaf at the end of each small branch,and conical flower clusters with three stamens.They also produce shoots in the autumn and winter.Gelidocalamus species are mainly found in the low-altitude south regions of the Yangtze River in China.The Nanling Region is the distribution center of species diversity of this genus.Inhabiting in the shade,cool and humid places of forests and ditches,these plants occur in patches,and they are valued for their ornamental and edible qualities as well as their ecological balance effects.However,the phylogenetic relationship of this genus is still controversial.In this study,the genetic relationship among the species of this genus was preliminarily investigated by phylogenetic reconstruction of chloroplast gene segments,which provided reference for deepening our understanding of the evolutionary history of bamboo plants.[Method]This study collected 82 species from 26 genera belonging to 11 tribes of the Arundinarieae and six species from Bambusa and Dendrocalamus as samples.Seven chloroplast gene segments,including rpl32-trn L,rps16-trn Q,trn C-rpo B,trn D-trn T,trn T-trn L,trn G-trn T(t),and mat K,were utilized to reconstruct the phylogenetic relationships of Gelidocalamus and its close relatives.Molecular clock estimation was employed to reveal the origin and divergence times between taxa.[Result]The phylogenetic analysis indicates that Gelidocalamus was a paraphyletic group,with its members clustering in two branches of the Arundinarieae tribe:the Shibataea clade(IV)and the Phyllostachys clade(V).The divergence time estimation suggests that the IV and V branches diverged around 5.44 Mya and 3.41 Mya,respectively.Apart from G.monophyllus,the other species of Gelidocalamus gradually diverged around 3 Mya.[Conclusion]Gelidocalamus is not a natural monophyletic group;G.rutilans should be classified under the genus Bambusa;G.annulatus may have originated from hybridization between Gelidocalamus and Bambusa;G.dongdingensis is closely related to I.tongchunensis and may belong to the genus Bambusa or represent an independent branch.This study performed the reconstruction of the phylogenetic relationships within Gelidocalamus,and the systematic position of the members in this genus was preliminarily expounded,which provides reference for the attribution of controversial groups.
temperate woody bambooGelidocalamus Wenphylogenetic relationshipdivergence time estimation