Systematics Studies On Endemic Plants Of Platycarya (Juglandaceae) In Eastern Asia

Platycarya is a single genus of Juglandaceae. The unique characteristic of fruit shape is obvi-ously different from other species. The Flora of China that was published in China record two species. They are P. strobilacea and P. longipes. But the Flora of China that was published in foreign country recorded only one species that it is P. strobilacea in 1999. Platycarya have been published other six species that they are P. longzhouensis, P. simplicifolia, P. simplicifolia var. ternata, P. strobilacea var. coreana, P. Castaneopsis, P. manchesterii, The P. castaneopsis and P. manchesterii are fossil species. And the P. simplicifolia var. ternata, P. strobilacea var. coreana, P. longzhouensis and P. simplicifolia are only distributed in limestone habitat. Distribution area is very narrow and lack of a sufficient number of specimens. Most taxonomists consider them to be a mutant in the Platycarya, both as a synonym of Platycarya.This study depth to explore the issues of classification and affinity in Platycarya, from the morphology, pollen morphology, leaf epidermis morphology, cytotaxonomy, molecular systematics. In order to provid data for the systematics and species biology of Platycarya.The main research results are as follows:1. Biological characteristics of observationMaking a comparison to the P. strobilacea, P. longipes, P. longzhouensis and P. simplicifolia four species of flower, fruit, leaf morphological characteristics, it turned out that the morphologi-cal characteristics of P. longipes and P. longzhouensis are similar; P. simplicifolia has greater difference from other three species. Namely P. longipes and P. longzhouens have a closer genetic relationship. Relationship between P. simplicifolia and another three species are far. Phylogenetic relationship are farthest of P. simplicifolia and P. strobilacea.2. The pollen morphology of observationObservation of pollen morphology under scanning electron microscope. There are both connections and differences between the four species that they are P. strobilacea, P. longipes, P. longzhouensis, P. simplicifolia. Such as surface grain of four plant species are granular ornamen-tation and hook. But there is a big difference of germination hook, hook shape and surface concave ornamentation. More support is divided into four species from the sporopollen analysis of P. strobilacea, P. longipes, P. longzhouensis, P. simplicifolia.3.The leaf epidermis morphology of observationThere are both connections and differences between the four species. Under optical microscope, four types of plant stomata arrange in random. And the leaf lower epidermal anticlinal wall style, cell shape and size have slightly different. The results show that the under the leaf epidermal characters are similar of P. longipes and P. simplicifolia, P. longzhouensis and P. simplicifolia. This can be further inferred their genetic relationships with closer. Leaf epidermal characters are quite similar of P. strobilacea, P. simplicifolia and P. longzhouensis, namely their genetic relationships with closer. Under the scanning electron microscope, the leaf epidermis morphology characteristics have great different within the genus. According to the difference recognize that the genera are divided into four species from the sporopollen analysis of P. strobilacea, P. longipes, P. longzhouensis, P. simplicifolia.4. CytotaxonomyThe chromosome number of P. strobilacea may be 2n=24; x=12; the original base for x=6. The chromosome number of P. longipes may be 2n=26, x=13. The chromosome number of P. longzhouensis may be 2n=25,26; x=5,13. The chromosome number of P. simplicifolia may be 2n=25,26; x=5,13.5. Molecular SystematicsSelection of four species of Platycarya, and combination with gene databases (GenBank) published Cyclocarya, Pterocarya, Carya, Juglans related species of Juglandaceae. Using MEGA5.05 software study on experimental data of molecular phylogeny. This research choose chloroplast genome(cpDNA) trnL-F, matK; nuclear genome(nDNA) ITS, determination and analysis these gene sequence. Using MP, NJ and bayesian inference method structure phylogene-tic tree. From the gene sequence analysis that species gene is more conservative. The same gene fragment in the interspecific difference is insignificant. Genetic distance analysis for ITS+trnL-F+matK show that P. longzhouensis is divided into a new species form Platycarya is possible. Phylogenetic tree showed that Platycarya and Cyclocarya have a relatively close systematics position. Four species of Platycarya get togethe in the each of phylogenetic tree.According to the morphology, pollen morphology, leaf epidermis morphology, cytotaxonomy, molecular systematics of analysis, the results show that the Platycarya may have four kinds of species. They are P. strobilacea, P. longipes, P. longzhouensis and P. simplicifolia. Also concluded that P. simplicifolia is probably the most evolution of a species, the P. strobilacea is probably the most primitive one species.