Hybridization Breeding Thought Evolution Of Populus In China And Some Main Cultivation Genetic Similarity Analysis

Populus is an important tree species in forest tree breeding, is also an importanttimber species in molecular biology, widely cultivated in the world.To date,Populuscross breeding in China has been carried out for decades, the new varieties are emerging,but not much outstanding performance.System analysis on hybridization breeding ofPopulus has the vital significance for deepen their understanding of breeding basis,breeding strategy and breeding efficiency.In this study, our founding decades bred varieties as the research object,and analyzedon the changes of their genetic relationships、growth and quality traits,explored the conceptof Populus breeding and molecular markers were used to study the relationship betweenspecies with good performance to support the analysis of the results.. The results are asfollows:1. Although Populus launched many varieties in China,but the breeding germplasmbase is relatively narrow,make our country bred hybrids breakthrough difficulty increase inthe future. Before the90s, varieties are mainly descendants of P. simonii Carr. and P. nigravar. Italica(Muenchh.)Koehne,90’s mainly are descendants of I-69, I-63, geneticbackground is relatively single.2. Populus cultivation area expanded from the north of the Yellow River area to themiddle and lower reaches of the Yangtze river.3. rotation period of Populus became shorter, mainly from the original6to10years tothe current5to7years. The fiber length, fiber width grows wider trends.4. Randomly selected48DNA samples to preliminary screen56pairs SSR primers,the results showed have53pairs of primers PCR products can be amplified bands andpolymorphic primer composition ratio higher, indicated that the SSR molecular markertechnology is an efficient means to detect the genetic structure of Populus.5. Among the56pairs of primers sceened out14pairs of primers used for SSRprimers analysis,79bands amplified out in total, polymorphism loci is75, the level ofpolymorphism is94.9%, the number of primer amplification is between2to9, the averageof5.64bands. Showed that the tested material has a wide variation in DNA level.6. Genetic similarity clustering based on the material, the genetic similarity coefficientbetween0.5436~0.9773, the average similarity coefficient was0.7604, and at the geneticsimilarity coefficient of0.5830Populus materials are divided into three groups, supportedthe conclusions of narrow breeding base. Classification results and morphological traits aredeal with genealogy evolution, Indicate that SSR can more accurate detection of geneticbackground and genetic relationship between genotypes.