Analysis Of The Genetic Diversity Between Different Sesamia Inferen Population And Various Borer Spiecies By DNA Barcoding

In this study,DNA barcoding technique was employed to analysis the genetic divergence between 9 borer species,11 Sesamia inferen populations from different geographic regions and 6 from differdnt host plants.This work tried to ascertain the population differentiation among polyphagous stalk borer moths,and the feasibility to identify stem borers with DNA barcoding.Thus,new technique could be developed for enhancement of pest monitoring and control.The results were summarized as follows.1.Genetic differentiation of Sesamia inferens from different regions.Specific primers previously used for cloning the COI gene fragment of Sesamia inferen from 11 different regions(Yuanyang Henan,Jinhua Zhejiang,Guixi Jiangxi,Guangzhou Guangdong,Wuhan Hubei,Nanjing Jiangsu,Changsha Hunan,Wuming Nanning Guangxi,Huaxi Guiyang Guizhou,Qingbaijiang Sichuan).We get the expected 180 COI gene fragments of 709bp in length.Through BLAST in NCBI,the sequences were confirmed to be right ones.Then diffenrt data analysis methods were used to compare the genetic diversity among these populations.The results of genetic distance showed that Huaxi Guiyang Guizhou and Guangzhou Guangdong?Wuming Nanning Guangxi have a nearer relationships(0.01),the others ' s genetic distances(0.3?0.43)were little far with each other.The Tajima's D neutrality test revealed there exsit intraspecific genetic differences in both Huaxi Guiyang Guizhou and Qingbaijiang Sichuan populations,also Wuming Nanning Guangxi population have a significant intraspecific genetic differences.The analysis of Fst and its P values test told us that populations in the upper reaches of the yangtze river have a very high level of genetic differentiation with populations in the mid-yangtze and lower reaches of the yangtze river.However,the level of genetic differentiations between populations from mid-yangtze and lower reaches of the yangtze river were all below the medial level except data between Changsha Hunan and Nanjing Jiangsu.Also,there were outlicrs between the populations in one area which genetic differentiation out to be high level.The phylogenetic tree clust the populations of Wuming Nanning Guangxi and Huaxi Guiyang Guizhou just in one branch.Species in middle and lower reaches of the Yangtze River are nterleaved,with no apparent clustering of laws.Qingbaijiang Sichuan population appear only in one of these branches,indicating higher levels of genetic differentiation with other species.Mantel Test results show that there is no relationship between genetic distance and geographic distance.2.Genetic differentiation of Sesamia inferens on different plants.With the same method,we use Sesamia inferen on different host plants in two different places as experiment samples.The samples were collected on rice,rice stubble Eleusine indica(L.)Gaertn,Echinochloa crusgalli(L.)Beauv,Vetiveria zizanioides L in Wujiang of Jiangsu province.and on rice and Zizania latifolia turcz in Huangshi and Xiangyang of Hubei province.Results indicate that there's no genetic differentiation among S.inferen on different host plants.Gene flow of populations on 5 different hosts in Wujiang Jiangsu is 14.24,suggesting that the gene exchange among these populations is very rich.NJ phylogenetic tree of S.inferen on varous host plants in Huangshi and Xiangyang Hubei showing interleaved indicates that there is no genetic differentiation.We considered whatever the distance between various hosts is near or far,there is no genetic differentiation.This is perhaps because of the un-full match between the rice growing season and the pest infestation period,and also inter-migration among its wide variety of host plants.3.Genetic differentiation among different stem borers.We use the DNA barcoding technology to study the genetic differentiation among 9 stem borers on the basis of our previous study.The NJ phylogenetic tree shows that the DNA barcoding can divide the samples into right clusters and reveals the genetic relationships between different species.We considered DNA barcoding can well achieve the goal of classifing different species,which provided great help for morphological identification.Integrating the previous experimental data,we get the NJ phylogenetic tree of 11 different populations.We considered that DNA barcode technology can achieve the purpose of classifing the stem borers accurately.It can be established as an effective mothed to identify different instars in the field survey.The COI sequence of the 11 species of stem borers provided by this work can be used as DNA barcoding sequences for identification of these borers in field survey.In conclusion,we collected 276 S.inferen from different regions and hosts,and another 84 stem borers of 9 different species.Using the existing mitochondrial DNA primers we cloned 360 COI gene fragments from each of these borers.Analysis with different methods found no genetic differentiation among different geographic and host populations of S.inferen,except for the geographic populations of Guangxi and Guizhou which have a little genetic differentiation.The analysis of 11 stem borer species confirmed that DNA barcoding can reveal the genetic relationship accuratly.It also can be used in the field to identify these borers.