| The genus Phyllostachys Sieb.belongs to the family Gramineae,subfamily Bambusoideae,tribe Shibataeeae.It is the largest genus in subfamily Bambusoideae.Bamboos are of notable economic,ecological and social significance.China has the most abundant bamboo resources of the world.East China is rich in resources of the genus Phyllostachys.Taxonomy of bamboo species is problematic and controversial,becoming a bottleneck restricting the development of bamboo industry.Therefore,the genetic variation and phylogenetic relationships among species of the genus Phyllostachys in East China were investigated based on phenotype,chloroplast DNA(cpDNA)sequences and AFLP of nuclear genome in the present research.The main research and results are as follows:(1)The morphological variation and phylogenetic relationships of 43 bamboo species were analyzed based on six phenotypic quantitative traits(rod diameter,internode length,leaf length,leaf width,leaf aspect ratio,and leaf area).Results showed extremely significant differences in each phenotypic trait among all bamboo species studied.The variation coefficient(CV)ranked from largest to smallest as internode length(0.185)>leaf area(0.142)>leaf length(0.111)>leaf aspect ratio(0.067)>rod diameter(0.033)>leaf width(0.017).Correlation analysis displayed highly significantly positive correlation for internode length with rod diameter and leaf width,respectively,and for leaf width with leaf length.Leaf area had extremely significantly positive correlation with leaf length and leaf width,respectively.Leaf aspect ratio had highly significantly positive correlation with rod diameter and leaf length,respectively.However,rod diameter had extremely significantly negative correlation with leaf width,and significantly negative correlation with leaf area.Leaf aspect ratio had extremely significantly negative correlation with leaf width.The clustering tree clearly distinguished all the 43 bamboo species studied,separated two genera Phyllostachys and Pseudosasa in different groups,and generally supported the traditional classification.But separation between section Heterocladae and section Phyllostachys was not distinct in topological structure within genus Phyllostachys,which can be due to the limitation of morphologic analysis.(2)The genetic variation and phylogenetic relationships of 43 bamboo species were investigated based on four cpDNA sequences,namely three intergenic regions trrn H-psb A,trn T-L,and trn K-rps 16,and one trn G intron.Analyses with combined matrix of four sequences showed the variable sites(Vs)=439,mutation rate=14.6%,the main variable sites found in sequences of trn G intron and trn T-L,polymorphic site(s)=426,single nucleotide polymorphism(Pi)=1.13%,haploid number(h)=43,and haplotype diversity(Hd)=0.996.The phylogenetic tree generated using NJ(Neighbor-Joining)analysis separated clearly all the bamboo species studied.Two genera Phyllostachys and Pseudosasa formed two different clades.Species within genus Phyllostachy were basically divided into two major groups,one corresponding to section Phyllostachys,another to section Heterocladae.The topological structure of phylogenetic tree based on cpDNA sequences partially supported the traditional classification based on morphology.However,some species of section Heterocladae were mixed in clade of section Phyllostachys,which can be attributed to introgressive hybridization between the two sections,and also the highly conserved nature of cpDNA sequences,and limited number of cpDNA sequences used in the study.(3)The genetic variation and phylogenetic relationships of 45 bamboo species were analyzed based on AFLP markers.Low level of genetic diversity was detected within the genus Phyllostachys with the number of polymorphic loci(N)=200,percentage of polymorphic loci(PPL)=90.50%,effective number of alleles(n_e)=1.090,expected heterozygosity(He)=0.0726,and Shannon’s information index(I)=0.1404.The phylogenetic tree generated using NJ(Neighbor-Joining)analysis distinguished all the bamboo species studied clearly.Two genera Phyllostachys and Pseudosasa fell into two different clades with high values of bootstrap support.The topological structure of phylogenetic tree generally supported the traditional taxonomic assesment.However,section Phyllostachys and section Heterocladae were separated poorly,which may be caused by natural interspecific hybridization,shared ancestral polymorphisms or balancing selection.Additionally AFLP as dominant markers can also cause the homoplasy in phylogenetic trees.In summary,the present research revealed genetic variation and phylogenetic relationships among species of the genus Phyllostachys in East China based on phenotype,cpDNA sequences and genomic markers AFLP,generally supported the traditional classification based on morphology.Controversial classification placement of some species were also discussed.Results of the present research will provide theoretical basis for bamboo taxonomy,be of significance for further research,conservation and utilization of bamboo resources,and efficient development of bamboo industry. |
