Taxodiaceae - its systematics and characteristics of species

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1.PurposeThe purposes of this research program on fifteen species and one putative hybrid of Taxodiaceae are : (1) to make Taxodiaceae systematics by RFLP analysis on genes of cpDNA,(2) to clarify the characteristics of the species by means of ecological, ecophysiological, and population genetic methods in combination, and (3) to have clear understanding on phylogenetic relationship of sugi to other Taxodiaceae species based on the results of (1) and (2).2.Research items and research methods(1) Molecular classification on the species : RFLP analysis of genes on chloroplast genome.(2) Research on ecological characteristics of the species : investigation on environmental factors ; vegetational analysis ; and accumulating reports and other documents of ecological studies.(3) Research on ecophysiological characteristics of the species : analysis for photosynthesis and transpiration of each species.(4) Population genetic survey : Isozyme analysis and/or RFLP analysis on nuclear DNA,cpDNA an … More d mtDNA.(5) Integration of above results to have understanding on the phylogenetic position of sugi in Taxodiaceae systematics.3.Results and Discussion(1) Taxodiaceae systematicsWe have investigated a molecular phylogeny of conifer including all of Taxodiaceae species using RFLP of PCR-amplified six chloroplast genes. The data sets produced similar basic parsimonious trees when the Wagner parsimony and the neighbor-joining (NJ) methods were applied. Cupressaceae and Taxodiaceae are closed related families each other, and Sciadopitys verticillata is the basal lineage of Cupressaceae and Taxodiaceae(2) Characteristics of the speciesWe have determined the genetic diversity in natural populations of C.japonica using 12 allozymes. The amount of genetic variation within the species is high but most is found within populations with little among populations despite their isolated distribution. This pattern of genetic diversity is inferred to be the consequence of the following : the distribution of this species in the past was wider and more continuous than it is now ; a high rate of gene flow occurs ; and the long life span. Moreover we have found the mode of rDNA variation in natural populations of Sciadopitys verticillata. This species have a higher rDNA variation within population and the variations within populations are different from each other. Less