A Study Of Phytogeographic Distribution And Molecular Systematics Of Subfamily Atriplicioideae In China

This study used phytogeography methods in order to analyzed the floristic elements of Atriplicioideae (Chenopodiaceae) in China according to the unit of species. At the same time, the molecular phylogenetic trees of this subfamily were constructed based on the nr DNA ITS by MP, ML and BI. Then the relationships among these taxa was discussed. The main results are summarized as follows:The results of analysis which concentrated on distribution and floristic characteristics in China can be stated as follows:There are total 19 species belong to temperate elements, They mainly occur in arid desert regions. Only 3 species pertain to subtropical elements (Atriplex repens Roth; Atriplex maximowicziana Makino; Atriplex nummularia Lindl.), they mainly distribute in Fujian, Guangdong, littoral area in Taiwan. Microgynoecium tibeticum Hook. f., Axyris prostrata L., Krascheninnikovia compacta (Losina-Losinskaja) Grubov and Archiatriplex nanpinensis G. L. Chu are Tibetan Plateau elements, they appear to the altitude of 2000m region.The primary floristic characteristics of the subfamily in China can be listed as follows:(1) Endemism is obvious:Archiatriplex G. L. Chu and Microgynoecium Hook.f. are endemic in Asia. Krascheninnikovia arborescens (Losina-Losinskaja) Czerepanov is endemic in China. Krascheninnikovia ewersmannia (Stschegleev ex Losina-Losinskaja) Grubov, Atriple cana C. A. Mey., Ceratocarpus arenarius L. are only distributed in Xinjiang.(2) There are both floristic elements of the primitive and advanced:primitive such as Archiatriplex G. L. Chu, Krascheninnikovia ceratoides (Linnaeus) Gueldenstaedt. Advanced such as Krascheninnikovia compacta (Losina-Losinskaja) Grubov.(3) There is a typical temperature desert distribution:most species of the subfamily are temperate elements. They form an important part of predominant species in arid and gobi zone.(4) There is close connection with Central Asian elements:About 82.14% of total species in Xinjiang province,42.86% distribute in Gansu province and 18 species in common with Central Asian.Phylogenetic relationship of this subfamily in China was evidenced from nrDNA ITS, the main results are stated as follows:(1) Atriplicioideae could not formed a monophyly group:Its three genera are monophyletic groups.(2) Relationship between Atriplex and Chenopodium:In agreement with former research, Chenopodium is a polyphyletic group and have a close relationship to Atriplex.(3) The relationship of Obione C. A. Mey. and Atriplex L.:There is not enough molecular evidence to separate Obione from Atriplex. We divide Atriplex L. into two parts:Atriplex 1 and Atriplex 2.(4) Systematic positions of some groups:Microgynoecium tibeticum Hook. f. is a transitional species between Atriplex and Chenopodium. Krascheninnikovia has some differentiations within its genus and close to Axyris. They have a close relation with each other, but distant relationship with Atriplex.(5) Relationship of some species between China and other countries:some species in other countries have a close relationship with Atriplex 2 in China. It is a molecular evidence for the cultivated of the subfamily.