A Phylogenetic Study Of Partial Species In Genus Iris L. From China

Genus Iris Linnaeus belongs to family Iridaceae,distributing in the northern temperate zone.China is an important distribution center of genus Iris,there are more than sixty species(21 endemic)in China.Adaptive radiation and convergent evolutionary history of genus Iris have led to high phenotype similarity between different species.Both the interspecies classification and phylogeny need further study,and the subgenus classification systems are sustaining controversial.The complex evolution history and vast territory of China,both have resulted in some potential species which have not been described and published.Regarding the issue above,in this study,scanning electron microscopy was used to conduct palynological studies on 25 species,3 varieties,1 forma of genus Iris and Belamcanda chinensis.The results show that monocolpate is the original trema type of genus Iris.Based on palynological evidence,this article supported the independent status of genus Belamcanda Linnaeus,and I.dichotoma should belong to genus Iris.The phylogenetic status of I.forrestii and I.wilsonii etc.species of Series Sibiricae,Subgenus Limniris were discussed.This article supported the independent status of I.forrestii and I.wilsonii,and supported I.bulleyana f.alba merged into I.bulleyana.There are a large number of natural hybrid groups and intermediate types as I.chrysographes and I.bulleyana,which still need further studies and more discussion.The pollen grains characteristics of I.ruthenica var.nana,I.uniflora from Section Ioniris and those of I.laevigata and I.ensata from Subgenus Limniris have quite high similarity.The characteristics of pollen grains of I.maackii and I.pseudacorus are highly similar,it is necessary to further verify whether I.maackii is a geographic subspecies or just a wild population of I.pseudacorus.This study supported the independent status of I.tigridia and I.pandurata.Two new species were discovered and described,and named Iris zhaoi Y.G.Shen et M.Zh.Sun et W.Zhao et Hongxing Xiao sp.nov.and Iris yutangii M.Zh.Sun et W.Zhao et H.X.Xiao,sp.nov..In order to determine the taxonomic status of I.zhaoi and I.yutangii,and reveal the phylogenetic relationship with related species,molecular systematics study was conducted based on cpDNA and ITS gene sequences.The results showed that I.zhaoi and I.yutangii obtained a well-supported monophyletic evolution branch,I.confusa and I.japonica are closely related species of I.zhaoi.The palynological evidence also supported the new species status ofI.zhaoi.And I.bulleyana is closely related species of I.yutangii.The Flow Cytometry was used to estimate and analyze the genome size of 13 species and 1 variety of genus Iris.The results show that I.potaninii has the minimum genome size at 2.652 Gb and I.songarica has the largest genome size at 6.793 Gb.Combined with palynological evidence,this study discussed the phylogenetic status of controversial species such as B.chinensis and I.dichotoma.This study made supplements to the descriptions of <Flora of China>(Iridaceae),and provided new scientific basis and reference for the phylogenetic study of Iris.