Genetic And RAPD Analysis Of Transgenic Cotton Obtained Through Introducing Open-bud Via The Pollen Tube Pathway Method

The open-bud cotton, which has advantage of avoiding emasculation by hand in hybrid seed production, has profound potential in application of cotton heterosis. However open-bud cotton was mainly selected from interspecific hybridization of Gosspium barhadense and Gosspium hirsutum, which had defects of few bolls, small bolls, poor yield traits and so on. Therefore, breeding for open-bud cotton with insect resistance aroused extensive concern among cotton breeder.Via pollen-tube pathway the genomic DNA of the open-bud cotton Yi 9-3 was introduced into the insect-resistant cotton 707-1. The variant line with open-bud was obtained from their segregation generation. The morphologic features, yield traits, resistance to the cotton bollworm and hereditary property of the variant were investigated. The analysis of RAPD and ITS was undertaken among the donor line, the receptor line and the variant line. The main results were as follows:1 The length of the extruded stigma in the variant was measured in the day before blossoming. The results indicated that the length was stable and the character of open-bud was stabilization in three generations. The morphologic features of the variant were similar to the receptor in two-year observation.2 The yield traits of .the open-bud variant, ie. the bolls per plant, weight of boll, lint index, seed cotton yield and ginned cotton yield, increased significantly comparing to the open-bud donor.3 Evaluation on insect-resistant for the receptor and thevariant were undertaken in laboratory. The result showed that the variant had resistance to the cotton bollworm as the receptor, and the character of insect-resistant for the variant was hereditable.4 Genetic analysis of the open-bud variant indicated that hybrid F1 of the variant and the Simian No. 2 with normal bud showed normal bud, and F2 population were recorded 3 normal bud and 1 open bud, while backcross with the variant were recorded 1 normal bud and 1 open bud . It is, therefore, evident that the character of open-bud was controlled by a pair of recessivegene.5 The genetic diversity of the donor, the receptor and the variant was studied by RAPD (Random Amplified Polymorphic DNA). 49 arbitary primers out of 50 had generated 176 DNA bands among three cotton materials. The analysis of polymorphic bands showed the DNA sequences amplified by primer S462 were molecular markers of the character of open-bud.6 The sequences of ITS-1 (Internal Transcribed Spacer) and 5.8S rDNA in the donor were same as the receptor and the variant. And there was one base of ITS-2 different between the donor and the two later, that is the base G of the donor was insteaded by base A in NO. 682bp. The result indicaded that the sequences of ITS and 5. 8S rDNA were perfectly conserved among three materials, and the variant had more homogenous hereditary substance with the receptor.