Taxonomic And Phylogeographic Study Of Begonia Edulis And Its Relatives

Begonia edulis Lévl.,a perennial herb in Begoniaceae which used for ornamental,edible,and medicinal purposes,is found on two kinds of habitats:soil and karst.With rich morphological variation in different niche,this species is morphologically indistinguishable with B.truncatiloba.,B.dielsiana,B.emeiensis and B.digyna.In order to revise B.edulis and its relative,field exploration and specimens surveys,sequences on ITS and three cpDNA(rpl16,trn C-ycf6,trnL-trnF)pairs of 27 populations of Begonia and its related species were conducted.Meanwhile,based on cpDNA(rpl16,trnC-ycf6)sequences,the genetic geography of 16 populations of Begonia edulis were studied.The results were as follows:(1)B.emeiensis C.M.Hu ex C.Y.Wu et Ku as a synonym treatment of B.dielsiana E.Pritz.ex Diels(2)Two groups,Palmata and Laminariae of sect.Platycentrum based on leave lobed or deep lobbed were not supported monophyly based on DNA sequnces.Deep-split and shallow split species,B.pedatifida and B.macrotoma form one clade,B.edulis and B.truncatiloba with similar leave morphology clearly form two clades.Parallel evolution between the shallow lobe and the deep lobe in the group was confirmed.(3)Two new distributions were recorded on B.dielsiana in Guizhou province,one new distribution site on B.edulis was recorded based on herbarium In Anyuan,Jiangxi province.And natural hybridization population between B.hemsleyana and B.truncatiloba was discovered in Pingbian,Yunnan province.(4)B.edulis has a high diversity in habitat,morphological and genetic diversity.Two chloroplast fragments(rpl16,trnC-ycf6)were combined and detected 19 variant sites,17haplotypes,of which 11 were unique haplotypes,and 8 populations had haplotype polymorphisms.The total genetic diversity(H_T)of B.edulis is 0.785,the genetic diversity(H_s)within the population is 0.199,and the haplotype polymorphism(H_d)is 0.926,with a high level of genetic diversity.AMOVA analysis results showed that the variation was mainly from the population(88.20%),and the genetic differentiation coefficient between populations was Fst=0.822.(5)It was inferred that the karst area in China-Vietnam is ice-stage refuge for B.edulis.(6)The genetic diversity variation of B.edulis occurred larger among populations than that of within population.Conservation attention should be paid on the habitats of different populations.