Clonal Variation And Transcriptome Association Analysis Of Resin And Wood Traits In Pinus Massoniana

Pinus massoniana Lamb.is the main timber and oleoresin species in south China.The capability of oleoresin yield and wood traits are two important economic characters.The genetic variation of the capability of oleoresin yield and wood traits was studied,and then the SNP sites associated with oleoresin yield and wood properties were mined through the transcriptome association study,so as to promote the improvement of oleoresin yield and wood quality of masson pine.In this paper,50 clones from 5 origins of masson’s pine clonal experimental forest in Zhejiang Laoshan Forest field were used as research subjects to study the genetic variation of masson’s pine among origins and clones within origins in terms of oleoresin yield,compositions,wood basic density and fiber morphology.Phenotypic data and genetic material of 204 clones from 9 origins of the second generation breeding population of pinus massoniana were analyzed.The main results are as follows:(1)The result of ANOVA revealed significant differences among origins and clones within origins for the capability of oleoresin yield and oleoresin compositions.The variation of clones within origins with the variance components ranging from 30.93%to80.89%was the main source of genetic variation.However,the significant differences were only observed among origins for all studied growth traits except crown width with the variance components of 40.13%to 52.89%.Diameter at breast height(DBH)exhibited positive genetic correlation with the capability of oleoresin yield(r _G=0.67).Among oleoresin compositions,only six compositions were moderately correlated with oleoresin yield.Strong genetic correlations were found mainly among the compositions within the same class of terpenes,especially for the sesquiterpenes.The hierarchical cluster analysis revealed monoterpenes are closely related to diterpenes,and clearly distant from sesquiterpenes.Finally,taking into account the capability of oleoresin yield,growth and oleoresin compositions,nine high pinene and eleven high abietic acid content of superior clones were selected.(2)The result of ANOVA revealed that there were significant or extremely significant differences in the basic density and fiber morphology of the wood among origins and clones within origins.The variation of clones within origins with the variance components ranging from19.37%to28.26%was the main source of wood basic density,fiber length and fiber length-width ratio.The variation of origins with the variance components(45.37%)was the main source of fiber width.There is a significant phenotypic and genetic negative correlation between basic densities of wood and fiber length and fiber length/width,but the correlation coefficient is not high and the basic densities of wood is not related to fiber width.The fiber morphology of juvenile and mature woods has a very significant phenotype and genetic positive correlation,but the phenotypic correlation coefficient was smaller than the genetic correlation coefficient.Based on growth,wood properties and the capability of oleoresin yield,seven superior clones were selected.(3)The sequencing yield of all samples is not less than 8G Clean Data.After quality control,the ratio of base mass value greater than 30 is as high as 85%,and the GC content distribution is 44.15%-46.75%.The second-generation sequencing results were combined with three-generation full-length sequencing as a reference genome for subsequent analysis.The population structure analysis of 204 clones divided the Pinus massoniana of the nine producing areas into two subgroups,and the Sichuan origin could be used as a subgroup separately.Through transcriptome association analysis of the samples,there are 95 SNPs significantly associated with lipogenicity;456 SNPs associated with turpentine components;and 25 SNPs significantly associated with wood basic density;There were 6SNP-related sites with fiber length,and no associated sites with fiber width were found.By annotating the genes at the relevant sites,it was found that some genes are involved in plant growth and development,protein degradation,sugar chain modification,signal transduction,retrotransposon and cell wall cellulose degradation.