Dispersal routes of Cercospora zeina causing maize gray leaf spot in China

The gray leaf spot caused by Cercospora zeina has become a serious disease in maize in China.The isolates of C.zeina from Yunnan,Sichuan,Guizhou,Hubei,Chongqing,Gansu,and Shaanxi were collected.From those,127 samples were used for genetic diversity analysis based on inter-simple sequence repeat(ISSR)and 108 samples were used for multi-gene sequence analysis based on five gene fragments.The results indicated that populations of C.zeina were differentiated with a relatively high genetic level and were classified into two major groups and seven subgroups.The intra-population genetic differentiation of C.zeina is the leading cause of population variation in China,and interpopulation genetic similarity is closely related to the colonization time and spread direction.The multi-gene sequence analysis of C.zeina isolates demonstrated that there were nine haplotypes.Genetic diversity and multi-gene sequence revealed that Yunnan population of C.zeina,the earliest colonizing in China,had the highest genetic and haplotype diversity and had experienced an expansion event.With the influence of the southwest monsoon in the Indian Ocean,C.zeina from Yunnan gradually moved to Sichuan,Guizhou,Shaanxi,Gansu,and Chongqing.Meanwhile,C.zeina was transferred directly from the Yunnan into the Hubei Province via seed and then came into Shaanxi,Henan,and Chongqing along with the wind from Hubei.

Molecular phylogeny and evolution of Scomber(Teleostei:Scombridae)based on mitochondrial and nuclear DNA sequences

A molecular phylogenetic analysis of the genus Scomber was conducted based on mitochondrial(COI,Cyt b and control region) and nuclear(5S rDNA) DNA sequence data in multigene perspective.A variety of phylogenetic analytic methods were used to clarify the current taxonomic classification and to assess phylogenetic relationships and the evolutionary history of this genus.The present study produced a well-resolved phylogeny that strongly supported the monophyly of Scomber.We confirmed that S.japonicus and S.colias were genetically distinct.Although morphologically and ecologically similar to S.colias,the molecular data showed that S.japonicus has a greater molecular affinity with S.australasicus,which conflicts with the traditional taxonomy.This phylogenetic pattern was corroborated by the mtDNA data,but incompletely by the nuclear DNA data.Phylogenetic concordance between the mitochondrial and nuclear DNA regions for the basal nodes supports an Atlantic origin for Scomber.The present-day geographic ranges of the species were compared with the resultant molecular phylogeny derived from partition Bayesian analyses of the combined data sets to evaluate possible dispersal routes of the genus.The present-day geographic distribution of Scomber species might be best ascribed to multiple dispersal events.In addition,our results suggest that phylogenies derived from multiple genes and long sequences exhibited improved phylogenetic resolution,from which we conclude that the phylogenetic reconstruction is a reliable representation of the evolutionary history of Scomber.