ISSRs And SSRs Analysis On The Population Genetic Structure Of The Cotton Bollworm Helicoverpa Armigera Hübner In China

The cotton bollworm Helicoverpa armigera Hubner (Lepidoptera:Noctuidae) is one of the most widely distributed agricultural pests throughoutAfrica, the Middle East, southern Europe, India, central and south-easternAsia, eastern and northern Australia, New Zealand, and many eastern PacificIslands. Host species for H. armigera come from a broad spectrum of familiesand include important agricul-tural crops such as cotton, maize, chickpea,pigeonpea, sorghum, sunflower, soyabean and groundnuts. Since 1990's, H.armigera has produced largish damage every year all over the world. Theirdistance migration and high adaptability make it infinite difficult to predictthe overrun and perform the integrated pest management (IPM) of H. armigera.Although considerable progress has been made in the general biology andecology of H. armigera, population genetic variation pattern and its impact onthe pest outbreak are not well understood.Microsatellite consisted of head-to-tail tandem arrays of short DNAmotifs(usually 1-6 bases), are a common component of the eukaryoticgenomes but are almost absent in prokaryotes. Microsatellite has become avery important tool in studying animal population genetic structure, gene flowand migration patterns among populations in recent years. In this study, weadapt the Enrichment way modified by Faye Barker and Paul Bloor' protocol.After digesting the cotton bollworm's genomic DNA, excising and purifyingDNA fragments in a range of 400bp~1000bp, ligating adaptor to purified DNA,capturing the microsatellite-containing DNA fragments by streptavadin-coated magnetic beads (Wangyuan Bio.Ltd.,China),ligating vector, trans-formating and sequencing we received five SSR makers. We established a newway and ideas of looking for SSR marker using streptavadin kit produced inChina.Zietkiewics et al. (1994) and Kantety et al. (1995) described a markersystem named Inter-Simple Sequence Repeat (ISSR) amplification. The ISSRanalysis involves the PCR amplification of regions between adjacent,inversely oriented microsatellites using a single simple sequence repeat(SSR)-containing primers that anchored with 1-4 bases at the 3'?or 5'?end.ISSRs markers are quick, easy to handle, high reproducibility and abundantpolymorphisms and thus has been found wide applicability in a variety ofsystems. In this study, using 15 ISSR markers we analysis the gene low oversix geographic populations in China, including Anyang, Kuerle, Wuhan,Nanjing, Jiujiang and Fuyang population. Total 138 DNA bands wereamplified, 125 of which (90.6%) were polymorphic. Cluster analysis indicatedthat there doesn't exit high gene flow among these investigated populations in2003. Besides, 8 primers were used for ISSR amplification in the 16individuals of laboratory population and natural population. The result shownthat the laboratory population had relatively lower genetic variation thannatural populations.After detecting by polyacrylamide gel electrophoresis, we selected nine SSRmarkers among our results and downloads from Genebank. With the remainingnine pairs, one primer of each pair was end-labelled with a fluorescent dye,either 6-FAM, HEX, or TEMRA. They were further studied on populationgenetic variation among seven geographic populations in China, includingAnyang, Kuerle, Wuhan, Nanjing, Jiujiang, Fuyang and Dunhuang population.Compared with the conclusion resulted by ISSR analysis, the result obtainedby SSR analysis can't reflect cotton bollworm' population genetic variation in2003. The factor maybe was few individuals and markers that we selected inexperiments.