Phylogeny And Biogeography Studies Of Chinese Brachypodieae

Brachypodieae have two model plants,Brachypodium distachyum and Brachypodium sylvaticum,so that Brachypodieae have important research value.And Brachypodieae also have some problems in the systematic position with Bromeae and Triticeae.We used maximum parsimony?maximum likelihood and Bayesian inference to analyse the relationship of three tribes,basing on sequences of DMC1?nrITS?psbA-trnH and DMC1 + psbAtrnH + nr ITS.The phylogenetic trees respectively basing on sequences of DMC1?nrITS and DMC1 + psbA-trnH + nrITS revealed that Brachypodieae?Bromeae and Triticeae fell into three separate clades.The phylogenetic trees basing on sequences of psbA-trnH show that Bromeae and Triticeae formed a one single clade.The results showed that Bromeae and Triticeae have experienced complex evolution.We estimate divergence times with BEAST,and reconstruct ancestral state with RASP.The result showed that Triticeae in china originated in northwest region,Species divergence time focused on 13-7 million of years which is consistent with the change of the cretaceous period in the Tibetan plateau.The result also showed that Brachypodieae in china originated in southwest region,Species divergence time focused on 3 million of years which is consistent with the change of the Pliocene period in the Tibetan plateau and the change of East Asian summer monsoon(EASM).Brachypodium pretense differentiation also occurred at this period.The study found that the distribution of Brachypodieae is closely related to the direction of the Hengduan Mountains and the Changjiang River.The mountains in south China and Qinling Mountains limit the expansion of Brachypodieae.Brachypodium pretense is endemic plant in China,but GBIF and Plant list think it is the local variant of Brachypodium sylvaticum as a different name.This study shows that Brachypodium sylvaticum from three places cluster a one single clade,Brachypodium pretense from three places cluster other clade,support the establishment of Brachypodium pretense.At the same time,I check herbariums on the spot and browse online herbarium photos,found that the pedicels of Braachypodium pretense greater than 2 mm is a unique.