Genetic Diversity And Population Structure Of Maize Landraces From South Maize Region In China

190 Depending too more on a few elite inbred lines results a rather narrow germplasm base in maize breeding in China,which has become the most significant restricts in the development of maize breeding.On the other hand,there are numerous maize landraces in China,in which abundant of genetic variations had accumulated, especially some favorable alleles.The genetic variations contained in the maize landraces provided a effective potential approach for the germplasm enhancement, improvement,as well as innovation of maize in China.Revealed by simple sequence repeat with tailed primer M13(TP-M13-SSR),we analyzed the genetic diversity and population structure of core maize landrace accessions conserved in China National Genebank(CNG) from South Maize Region,and the results were as follows:1.Fingerprinted with 54 simple sequence repeats(SSRs) covered the entire maize genome,a total of 549 alleles was detected across all the 194 landrace accessions, ranged from 5 to 23,with an average of 10.17 per locus.The average genetic diversity was 0.6148,and the minimum and maximum of polymorphism information content (PIC) were 0.2072 and 0.8651 respectively,averaged by 0.5738.All the parameters indicated a rather high level of genetic diversity of the landraces collected from South Maize Region.2.122 private alleles,with a proportion of 22.22%to all the alleles,were detected among 194 accessions totally.And among 10 provinces/regions included in South Maize Region,the accessions from Guangdong province contained more private alleles than the other provinces/regions,while the accessions from Anhui province contained the least,which indicated that landraces from Guangdong province showed a rather broader genetic background.3.Comparisons of genetic diversity among different provinces/regions included in South Maize Region revealed that landrace accessions from provinces of Guangdong, Fujian,and Jiangxi possessed relatively higher level of genetic diversity,while those from provinces of Anhui,Jiangsu,and Hunan possessed lower level.It is suggested that Guangdong might be the center of genetic diversity of maize landraces in South Region. 4.Analysis of molecular variance(AMOVA) indicated that 59.02%genetic variation was among populations,while 40.98%was within population.Pairwise comparisons of Fst showed that genetic deviation of landraces from Guangxi and Zhejiang,Hainan and Jiangsu were higher than the other regions pairs,with Fst value of 0.1549 and 0.1456 respectively,while the regions pairs of Anhui and Zhejiang, Guangxi and Hunan,and Jiangsu and Shanghai possessed lower genetic deviation, and the Fst value were 0.0097,0.0078,and 0.0062 separately.5.A distance based clustering method and a model based clustering method got the same results of the whole set of 194 landrace accessions from South Maize Region. 194 maize landraces were grouped into three clusters,and 88 accessions from provinces of Anhui,Fujian,Jiangsu,Shanghai,Zhejiang,and part of Jiangxi constructed clusterâ… ;clusterâ…¡was constructed by 49 accessions,all of which were from provinces of Guangxi,Hunan,and Hubei;and 57 accessions from provinces of Guangdong,Hainan,and part of Jiangxi constructed clusterâ…¢.Genetic diversity analysis of all the three clusters revealed that clusterâ… possessed the higher level of genetic diversity than clusterâ…¡andâ…¢,while clusterâ…¡possesed relatively lower level of genetic diversity than clusterâ… andâ…¢.6.Based on the population structure analysis,there maybe exist three different routines of maize dispersal in South Maize Region:one was that maize was firstly imported from Southwest on the land,and then dispersal to provinces of Guangxi and Hunan;another was that maize was directly imported into Guangdong province by ships,and then to the labor provinces of Hainan and Jiangxi;the remnant was that maize was imported into Fujian province on the sea,and then to the adjacent regions of Fujian,even dispersal to North China,which seem to be the mainly dispersal routine in South Maize Region in China.