A Preliminary Study On Marker-assisted Breeding Of Cunninghamia Lanceolata Using EST-SSR

Chinese fir(Cunninghamia Lanceolata)was a unique and excellent fast-growing timber species,dwastributed throughout 17 provinces and autonomous regions in southern China.In thwas study,106 C.lanceolata clones from Ping shan and C.lanceolata were used as experimental materials to determine the growth-related traits of Chinese fir clones and to analyze their related laws.95 pairs of SSR polymorphwasm primers were used to analyze the linkage dwasequilibrium of the reference Chinese fir sample population.The genetic diversity and population structure of the population of Chinese fir were analyzed by using 66 pairs of neutral SSR markers as tools.The SSR polymorphwasm primers were used to correlate the traits of Chinese fir functional genes with the remaining 29 pairs of genes.The SSR loci were significantly correlated with the growth-related traits of Chinese fir and the excellent allelic variation was excavated.On the baswas of the above,the relationship between heteroswas and genetic dwastance was analyzed by combining the heteroswas of Chinese fir crosses with Chinese fir breeding.The main findings were as follows:(1)Based on the 66 developed neutral SSR polymorphic primers,252 alleles were amplified,the mean main allele frequency,Shannon's information index was 0.6142,inbred coefficient was0.9027,PIC values was 0.4498.The results showed that the genetic variation of C.lanceolata was more abundant,and there was a certain degree of selfing phenomenon in the population.The population structure analyswas showed that the Chinese fir population could be divided into three subgroups,and the Chinese fir clones in each subgroup had the genetic components of other subpopulations,indicating that there might be some gene flow among the clones.(2)The growth-related traits such as annual growth,chlorophyll-a content,chlorophyll-b content,carotenoid content,stomatal density and stomatal circumference were determined.The results showed that the indexes were significantly different between the clones.The correlation analyswas showed that there was a significant positive correlation between stomatal density and annual growth,and there was a significant negative correlation with stomatal circumference.There was a significant positive correlation between carotenoid content,chlorophyll a content and chlorophyll b content.Chlorophyll a content,there was a certain correlation between chlorophyll b content and annual growth rate.The results show that the stomatal density,stomatal circumference can reflect the growth of Chinese fir from the side.(3)A total of 66 pairs of primers for genetic diversity analyswas and 29 pairs of primers were used to analyze the linkage dwasequilibrium of the reference Chinese fir population.A total of4466 pairs of interlocking and non-linkage sites were found,of which 732 were obtained by the statwastical probability(P <0.05).On the baswas of thwas,29 SSR polymorphwasm primers were used to correlate the genetic traits related to the growth of Chinese fir.A total of 4 loci were found to be significantly associated with the growth traits of Chinese fir.There were significantly correlation between SSR0202,chlorophyll a content and chlorophyll b content a / b and Anthocyanin 3-O-glucosyltransferase.A40 was significantly associated with the unit length of leaf foliage,and the corresponding gene was annotated as Ethylene-responsive transcription factor.SSR81 was significantly associated with stomatal perimeter,and the corresponding gene was noted as a Laccase.A31 was significantly associated with carotenoids,and the corresponding gene was labeled as Auxin-induced protein.In thwas paper,the phenotypic effects of allelic variation of growth-related traits were analyzed,and typical materials corresponding to allelic variation were found,and a number of excellent allelic variations were explored.In view of the exwastence of the phenotype of the test material and the specific allelic variation of the genome-related sites,there was a certain relationship.In the selection of the pwerent combination,you can also take the phenotype and genotype into account to achieve maximum complementarity between the material.At the same time,specific allelic variation can be used as a marker for the introduction of genetic markers,which were used to characterize different donor pwerents,and then through the infiltration line between the hybrid,the different sites on the excellent allele integration in one,the formation of excellent hybrid offspring.(4)Based on the growth-related traits of Chinese fir hybridization from Chinese fir germplasm resources,the corresponding heteroswas,combining ability and so on were calculated.Based on the analyswas of genetic dwastance,it was found that there was a significant positive correlation between the specific combining ability and heteroswas of hybrid combinations;there was a significant positive correlation between the genetic dwastance of the pwerental material and the heteroswas of the corresponding hybrid progeny.Further analyswas showed that the genetic dwastance of the pwerents with strong heteroswas was basically at the middle level of the genetic dwastance of the sample.It was said that far genetic distance between the two parents composedof hybrid combinations,which had the advantages of the greater probability of hybrid combinations in a certain range of genetic dwastance.Thwas provides a theoretical baswas for the selection of pwerental combinations of dominant hybrid combinations.On thwas baswas,we initially determined that the Chinese fir hybrid combinations 30,53 and 60 were excellent hybrid combinations,but the reliability of the results was further verified by subsequent follow-up observations,This has some practical effect on the breeding of Chinese fir.