Study On The Phylogeny Of Picea

Monophyly of the genus Picea has long been commonly accepted, but the subdivision of genus into subgenera, section and series is geatly debated ,and most systems of classification were formulated on few. We study respectively phylogeny of pollen morphology,cpDNA and mtDNA in Picea, in order to privod base in theory for taxonomy of the genus Picea:Pollen grains from 14 spruce species were examined using the scanning electron microscope, comprising:P.retroflexa, P.koyamai, P.asperata, P.meyeri, P.crassifolia P.wilsonii, P.likiangensis, P. balfouriana, P.purpurea,and P.linzhinensis in china; P.abies and P.omorica in European; and P.glauca and P.mariana in North America. Distinguishing characteristics of pollen morphology among the species were found using data statistic and photographic observation. Mean value of pollen size in 14 spruce species is from 84.59 to 103.18μm. According to morphological photography, two bladders distribute zygomorphic underside of corpus was found to being distinct edge of cap at near surface in corpus, its surface texture is smoother and it is not distinct variation among species. Germinal furrow forms clear striate between two bladders. According to clustering analysis, 14 spruce species was classified into two sections: Section. Castict and Section. Picea that spruce species was classified into tree subsections. Evolutional order in two section is Section. Castict→Section. Picea.Based on 160 trees of 32 species in the genus Picea, its phylogeny were investigated here using sequence analysis of the paternally inherited chloroplast matK, rbcl, trnT- trnF, atpA, chlB and pbsC, and the maternally inherited mitochondrial nad5 and nad7. We found the genus Picea passed inconsistent phylogeny beween cpDNA and mtDNA ,as well as among 6 chloroplast sequences. In 6 chloroplast sequences, 4 chloroplast sequences of high nucleotide diversity passed similar phylogeny of North American P.sitchensis standing basal position, we but 2 chloroplast sequences of low nucleotide diversity passed phylogeny of Asia P.polita standing basal position. 34 chloroplast haplotypes were dectected from 6 chloroplast combinating sequences of 33 species in the genus Picea, and its phlogeny was North American P.sitchenrsis and P.sitchensis standing basal position, other spruces were further divides into there clades. 9 kinds of mitochondrial haplotypes (A~I)were dected from 2 mitochondrial combinating sequences of 33 species in the genus Picea.In mtDNA phylogenic path, Haplotype A locates in cental position of phylogenic route including Asiea10 species and European 1 species, and is mitochondrial ancestor type in Picea, its phylogeny passed 4 routes and produced 8 other mtDNA haplotypes.Compared UPGM figure of pollen morphology with phylogenic path of 6 combinating sequences cpDNA , it found a highly consistent pattern in differetiation of pollen morphology and sequences cpDNA. So we believed pollen morphology cloud be considered as a available indicator in studying phylogeny in Picea. When phylogeny in the genus Picea is analyzed by cpDNA sequence, we should chooses sequences with high polymorphic sites, meanwhile also can't ignore sequences with low polymorphic sites it has polymorphic sites of representative differentiation of deep clades.We discussed geographic origin by combining pollen morphology with sequences cpDNA and mtDNA. It found that the genus Picea origined in Asia and it passed two independent migrations. At the first time it migrated from Asia to North America, during Creaceous Peroid before artistic depiction of asteroidal impact. Secondly, it migrated from North America to Asia, then from Asia to Euopean, during middle period Tertiary.