Genetic Diversity And Paternal Identification Of The Half-Sib Offsprings In Acacia Melanoxylon

Acacia melanoxylon,Acacia of Leguminosae,was originated in southeast Australia and mainly distributed at 24°～ 36° south latitude.Acacia melanoxylon is an exotic tree introduced into China in the early1990 s and belongs to evergreen tall trees.The lack of improved varieties restricts the cultivation and promotion of Acacia melanoxylon.The phenotypic variation of the half-sib progeny population was analyzed,and the genetic diversity was detected by SSR molecular markers.We also carried out paternal identification of the Superior individuals.It provided a basis for further breeding.The main results are as follows:1.Six phenotypic traits of 600 half-siblings from 30 acacia blackwood families were analyzed.The variation coefficient of phenotypic traits in 30 families was 19.75-37.43%,and the variation coefficient of seedling height was the smallest(19.57%).The coefficient of variation in leaf area was the largest(37.43%).The average CV value was 28.5%.The results showed that the 30 families had high genetic diversity and great breeding potential.2.Variance analysis illustrates that there were significant differences among 30 families.The family heritability of each trait was greater than the individual heritability,and the average family heritability is above 0.9,which indicated that it was controlled by higher heritability.The general combining ability effect value of 30 parents was estimated.From the point of view of growth characters,the seedling height character of pedigree 13 had the highest combining ability,indicating that the seedling height generated by the hybridization of clone 13 was higher than the population average.In general,the combining ability was the highest in line 16,indicating that the seed track diameter produced by the hybridization of clone 16 was higher than the population average.In terms of leaf traits,the traits of leaf length,leaf width and leaf area of pedigree 4 had the highest combining ability.The correlation between seedling height and ground diameter is the largest(R=0.767).We selected 3 superior families and 12 superior individuals.The 30 families was divided into four groups by phenotypic cluster analysis.3.Eight primers were selected from 52 primers for genetic diversity analysis,and they all amplified clear bands with perfect repeatability,polymorphism and specificity,mainly allocated between 50-200 bp.The number of alleles observed in the population is 1.3521-1.6056,the number of effective alleles was 1.2066-1.1942,the Shannon information index was0.1341-0.2113,and the Nei’s gene diversity index was 0.0832-0.1286.The expected heterozygosity at species level was between 0.8285 and 0.8414,the Nei’s total gene diversity(Ht)was 0.1203,the Nei’s intra-population gene diversity(Hs)was 0.1056,the Nei’s inter-population gene diversity(Dst)was 0.0147,the inter-population genetic differentiation coefficient(Gst)was 0.1227,and the gene flow(Nm)was 3.5755.The UPMGA cluster analysis classified 30 families into four categories,and 450 individuals were sorted into three categories by NJ cluster analysis.4.Taking the selected superior individuals as the material,the paternal identification was conducted under the condition that female parent was known.Male parent of each superior individual shall be identified on the premise of conforming to Mendel’s genetic law.The paternal parent of each individual was identified by the probability of parental relationship and SSR clustering analysis.