Genetic Diversity Analysis and Identification of Insect-resistant Cottons Based upon RAPD Markers

Genetic diversity analysis and identification of 14 different germplasm varieties(lines) from insect-resistant cotton by the random amplified polymorphic DNAs(RAPDs) techniques were reported.A total of 210 arbitrary primers were used to the 14 different germplasm varieties(lines) using RAPD techniques and finally 21 primers could produce steady polymorphisms.Total of 137 DNA fragments were scored among all materials,averaging 6.52 for each primer,of which,57(42.2%) bands were polymorphic.Cluster analysis by the unweighted pair group method of arithmetic means(UPGMA) showed that 14 varieties(lines) could be divided into two groups with genetic distance from 0.0351 to 1.056.The genetic distance was 0.0351 between JX011 and 33B,which indicated that it is more closely relationship in transgenic pest-resistant cottons than that of others.But the largest genetic distance,was 1.056 between 97014 and sGK321,which showed that the genetic base was narrow.An important reason would be that 97014 was the nectariless pest-resistant cotton,while sGK321 belonged to transgenic Bt+CpTI pest-resistant cotton.Cluster analysis revealed that 14 lines could be divided into two groups.The first group,which included 11 varieties,most were transgenic pest-resistant cotton.The second group,which included 3 varieties,were the nectariless pest-resistant cotton.This experiment demonstrated that RAPD analysis could reliably determine genetic relationships within a diverse array of cotton varieties.Genetic relationships and the genetic similarity obtained from the analysis in present study can help in the selection of parents for breeding purposes and be used for evaluation of varieties genetic diversity.The analysis revealed that it was corresponding to the geographical distribution and most of the lines had a narrow genetic base.