Construction Of DNA Fingerprint Of Cotton Based On SSR Molecular Markers

Cotton is an important economic crop in China, and has a close relationship to the national economy and people’s living standard. With the rapid development of molecular techniques, breeding technology is also faced with an unprecedented development. Molecular marker as the fourth genetic markers attracts particular attention by its unique advantage in various fields, such as crops, animal and human. Simple sequence repeats(SSR) is considered to be the preferred marker for construction of fingerprint at present. A variety of plants have built their own DNA fingerprints with SSR molecular marker, providing a theoretical basis for cotton purity and authenticity identification as well as a reference for parent selection in molecular breeding process. Main results of this study are as follows:1. Summarizing all kinds of literature and previous researches, more than 700 SSR primers were selected to detect 12 screening materials. We chose 291 SSR primers with polymorphic loci as alternative primers for core primers selection.2. Two hybrids and one F2 group were chosen to test 291 SSR primers. Two hybrids and their parents gained 8 and 7 primers showed co-dominant, respectively. 62 polymorphic primers were selected from the 291 SSR primers by parents of F2 group. Applying the 62 screened primers to analyse the polymorphism marker genetic linkage of F2 population, 10 linkage groups had been built. The average distance between markers was 20.38 c M, and the total length was 1039.32 c M, covered 20.78% of the cotton genome.3. 15 core primers were determined from 291 candidate SSR primers to construct DNA fingerprint of 20 cotton varieties. A total of 15 SSR primer pairs were polymorphic and generated 57 polymorphic loci, each marker detected 2~12 polymorphic loci with an average of 3.8. The polymorphism information content(PIC) ranging from 0.7308 to 0.9571, with an average of 0.8782. 20 materials could be distinguished completely by the constructed fingerprint.4. Using 15 screened primers to identify cotton purity and authenticity, theoretical purity of 4 samples were 95%, 88.89%, 100%, 93.33%, respectively. Fourteen SSR primers selected from 15 core primers were applied to fingerprint construction of 14 materials. Analysis results showed that the genetic similarity coefficient of the 14 accessions ranged from 0.4235~0.9529 with an average of 0.7776, indicating that the screened core primers can be used in other studies.