Identification Of Sugarcane Varieties By AFLP And SSR Markers And Its Application

The genetic diversity and fingerprint are important foundation for crop breeding,intellectual property protection and new variety promotion.Genetic distance among germplasm resources could be used as the basis for parent selection in cross breeding.The higher genetic distance among parents,the higher possibility of strong heterosis in F1 generation.DNA molecular fingerprint can be used as the variety identification card in variety rights protection and accurately confirm the true identity of a certain variety.During the variety promotion process,the genetic background of these targeted varieties and genetic smilarity between them and those already widely promoted varieties should be obtained.In the present study,fifteen pairs of S SR primers and 9 pairs of AFLP primes were used to scan the whole genome of sugarcane varieties(lines)from 3 rounds of national sugarcane varieties regional testing,and abundant fingerprint data of 38 new varieties(lines)were obtained.Then the genetic diversity of these sugarcane germplasm resources were analyzed,and the molecular fingerprints of these sugarcane varieties(lines)was constructed.It is expected to provide basic data at molecular level for the selection ofparents in cross breeding.The results of this study were as fo flows.(1)A total of 348 bands,248 of which were polymorphic,were amplified with 9 pairs of primers in AFLP marker,and the percentage of polymorphic loci was 72.26%.Besides,a total of 180 bands,176 of which were polymorphic,were amplified with fifteen pairs of primers in SSR marker,and the percentage of polymorphic loci was 97.78%.Through the calculation by NTSYS 2.10e software,the genetic similarity coefficient of these 38 new varieties(lines)was distributed between 0.668?0.847.In addition,the average PIC values of two molecular markers were 0.971 and 0.920,respectively,which demonstrated that these two markers had high variety discrimination ability.The data obtained here should provide a reliable foundation for the subsequent determination of genetic basis,group/cluster division and the principal component analysis and all the other related work.(2)In this study,the distribution characteristics of genetic similarity coefficient were innovatively studied using box plot,and the genetic basis of these 38 sugarcane varieties(lines)could be determined accordingly.The results showed that the genetic similarity coefficients of 38 sugarcane varieties(lines)and varieties(lines)of each series ranged from 0.680 to0.830 and concentrated on the range of 0.725?0.770.The concentrated range of genetic similarity coefficient of FN series sugarcane varieties was close to that of the YZ series sugarcane varieties,and it was also close to the concentrated range of genetic similarity coefficient of all the 38 sugarcane varieties.In addition,compared with other series sugarcane varieties(lines),the concentrated range of similarity coefficient of GT series sugarcane varieties was at a low level,while the concentrated range of similarity coefficient of YG series sugarcane varieties was at a high level.(3)These 38 sugarcane varieties were clustered by UPGMAalgorithm.The resulted showed that these 38 new varieties(lines)could be divided into two groups at the genetic similarity coefficient of 0.736 and a small subgrounp containing FN09-2201 and GT06-1492 could also be divided firstly.Besides,a small subgroup a containing ROC22 was obtained at the genetic similarity coefficient of 0.770.The subgroup a also included five other varieties(lines),FuNong07-3206,FuNong40,HaiZhe22,GuiTang09-12 and Liucheng07-150.So far,ROC22,the sugarcane variety with the largest planting area and also with excellent characteristic of high yield and high sugar,strong ratooning ability,has been recognized by the majority of farmers.During the promotion of sugarcane varieties,in addition to considering the genetic distance between those extention varieties and ROC22,the yield and quality traits similarity between ROC22 and those extention varieties in yield and quality traits should also be taken in to account.According to this rule,the recognition of famers on sugarcane variety can be enhanced and the promotion possibility of these varieties can thus be increased.In view of the high genetic similarity of these varieties in the same subgrounp,they are more likely to acquire excellent characteristics similar to those of ROC22 and has good promotion potential.However,in selecting cultivars to be popularized simultaneously with ROC22,it is necessary to select cultivars that are far from ROC22 in order to increase resistance to adverse environmental conditions in sugarcane populations.In addition,it is necessary to combine the actual field performance of each variety.(4)Based on the DNA fingerprint data obtained for 38 sugarcane varieties,the sugarcane DNA fingerprint database established in our laboratory before was updated.Specifically,the SSR fingerprints of these 38 sugarcane varieties(lines)obtained in this study were incorporated into the established sugarcane fingerprint database,and the data of the updated database was sorted out and the repeated varieties was eliminated.Then,all the varieties in the updated database were clustered and all the corresponding fingerprints of these varieties were drawn.This work is of positive significance to the popularization and application of fingerprint database in the identification of sugarcane varieties and also the selection of sugarcane parents in cross breeding.