Phylogenetic Analysis Of Gelidocalamus(Poaceae)

Gelidocalamus Wen(Poaceae: Bambusoideae),endemically distributed in the subtropical regions of China,is a genus of the trib.Arundinarieae with monopodial culum.So far,there are some controversies on the systematic position of the genus Gelidocalamus.Based on seven plastid DNA regions(rpl32-trnL?rps16-trnQ?trnC-rpoB?trnD-trnT?trnT-trnL?trnG-trnT(t)?Matk),the study reconstructed the phylogeny of Gelidocalamus and other 27 genera in the tribe Arundinarieae,and investigated the abaxial leaf epidermal micromorphology of 60 species(19 genera)of Arundinarieae by scanning electron microscopy.The main results are as follows:1.The molecular phylogeny shows that the genus Gelidocalamus is not monophyly,gathered with that of Shibataea clade(IV)or Phyllostachys clade(V).G.monophyllus and G.stellatus were not grouped into the same line.From the point of morphology,they are different.G.dongdingensis,G.solidus and G.rutilans are similar,respectively clustered with representative plants of the genus Indocalamus,indicated the taxon need to be taxonomically revised.G.stellatus and G.latifolius are closely related to that of Chimonobambusa.G.tessellatus and G.multifolius are closely related to some species of Ferrocalamus.G.kunishi is grouped with some species of Yushania.2.Papillae and its distributional patterns around the stomatal apparatus of the abaxial foliage leaf epidermis have important value in taxonomy.Micromorphological characters of the abaxial leaf epidermis of Arundinarieae can be divided into seven categories,as follows: I)A single morphology,including only papillae or stomata;II)Short papillae surround the visible stomata;III)4(or 8)elongated papillae overarching or invisible overarching on the stomata,visible or invisible stomata;IV)Four papillae around overarch the stomata and these papillae are surrounded by a few short papillae;V)more than ten elongated papillae forming inconspicuous arciform covers over the stomata;VI)the stomata is covered by elongated papillae;VII)several small papillae on the large papillae.3.The micromorphological characters of epidermal structure plays a limited role in the understanding 12 lineages of the tribe Arundinarieae,but maybe has some enlightenment on the classification of bamboos at the level of genus and species.Based on the molecular phylogeny,the type “The papillae surrounds or not obviously cover the stomata,and the stomata are completely visible.” may be the most primitive form of the epidermis structure in the temperate woody bamboos.In conclusion,the molecular phylogeny and the micromorphological characters of epidermal structure both suggest that Gelidocalamus is polyphyletic group.Some taxa(e.g.G.monophyllus,G.dongdingensis,G.solidus,etc.)need to be revised.