Genetic Diversity Of Corymbia Citriodora Revealed By Phen Otypic Traits And SSR Markers

Corymbia citriodora is a important fast-growing tree in the southern China,which has a very high ecological and economic value,but it still has large improvement potential.Based on6 natural provenance in Queensland,Australia and 6 provenance in China,we analyzed phenotypic variability of morphological traits of Corymbia citriodora provenance in seedling stage and at the age of 0.5 years,revealed the genetic diversity level of SSR markers of Corymbia citriodora provenance,and discuss the diversity and similarity of provenance genetic variation at home and abroad.The study could make better the selection and use of Corymbia citriodora breeding materials to provide theoretical guidance.(1)Variation in 12 morphological and growth characteristics were assessed in3.5-month-old: There were significant differences between seed sources in most of the characteristics assessed as well as among families within seed sources.The four most northern Queensland sources differed significantly from the other two Queensland and all Chinese seed sources.Stem pubescence and leaf pubescence were markedly differences among 12 provenance.Clear differentiation of the four most northern Queensland seed sources from all other sources was also clearly evident from the multivariate principal component analysis,and from the Chinese sources,that from Yuanmou in Yunnan seemed closest to the southern Queensland source(CAL.),and these two were distinctly separate from all other sources.The other five Chinese seed sources appeared closest to the southern most of the north Queensland sources,NHU.,and there were similarity of phenotypic traits among the 5 China provenance.(2)According to Corymbia citriodora phenotypic variation analysis at the age of 0.5 years we can draw the four most northern Queensland sources differed significantly from the southern most of the north Queensland sources,NHU.and all Chinese seed sources based on height,shape and the degree of leaf health,while NHU.Provenance seemed closest to the 6China provenance.And there were similarity of phenotypic traits among the 5 Chinaprovenance except Yuanmou in Yunnan;Coefficient of variation in QUA.provenance were higher than all seed sources,Gaofeng in Guangxi was the minimum.In 5 phenotypic traits leaf of roughness coefficient of variation is minimal,while the degree of leaf health is the largest.(3)13 pairs of SSR primers were utilized to study the genetic diversity and population structure of eleven Corymbia citriodora populations.The result showed that high levels of locus polymorphism from the 13 selected SSR primers,which EuceSSR0276 primers are the highest levels of locus polymorphism.The expected heterozygosity mean of the 13 SSR primers is moderate,while the Shannon's index(I)by 11 SSR primers were greater than 0.500.WMA.,GLE.,SIL.and QUA.Provenance had similar levels of genetic diversity,while NHU.provenance had the richest genetic diversity,seemed closest to Yuanmou in Yunnan.All other China sources had similar genetic parameters.The genetic differentiation was moderate among Corymbia citriodora provenance,whichindicating within-population accounting for the majority of genetic variations.And make Corymbia citriodora provenance together.(4)In combination with Corymbia citriodora morphology analysis and SSR marker analysis,we can found that Variation of phenotypic traits and levels of genetic diversity from the southern most of the north Queensland sources were all similar.While NHU.provenance had the richest genetic diversity,which appeared closest to Yuanmou in Yunnan.The genetic diversity of provenance from Guangxi and Guangdong were moderate,and together formed a distinct group according to the geographical location.On the whole The genetic differentiation was moderate among Corymbia citriodora provenance,and had higher Phenotypic variation.Meanwhile the higher levels of genetic diversity in Corymbia citriodora may suggest that great potential can be expected in breeding and focus should be paid to those populations with higher diversity and private alleles in germplasm management.The result shows that three methods for evaluation of genetic diversity of Corymbia citriodora is appropriate.