| Larix olgensis was one of important timber tree species in our country,which was not only applied in the afforestation,but also used as construction materials and paper making raw materials,etc.It was of great significance for the practical application to select the excellent clones based on the growth traits and wood properties.In addition,the content of lignin in wood had an important effect on paper making process,which seriously hampered the use of cellulose in papermaking process and caused damage to the environment.Therefore,it was meanful to research on lignin content for papermaking process.This study used 208 L.Olgensis clones in seed orchard of Siping city,Jilin province as the material,the growth traits and wood properties were measured,excellent clones were evaluated comprehensively and the SNPs of gene PAL were selected.According to association analysis,the SNP sites which were highly correlated with phenotypic traits were found.This study provided a reference for evaluation of excellent clones and also provided basis for the selection of marked sites in the process of molecular breeding.The growth traits(tree height,diameter at breast height,stem straightness degree and volume of timber)of 208 L.olgensis clones were analyzed.The results of variance analysis about growth traits showed there were significant differences(P < 0.01)for all growth traits among clones.The phenotypic coefficient of variation and repeatability of growth traits were 9.34-51.78 % and 0.362-0.849,respectively.Refer to the data of means,the comprehensive evaluation was performed.Ten clones(L70,L56,L82,L90,L59,L91,L61,L92,L86,and L64)were selected as excellent clones under a selection rate of 5 % using tree height,diameter at breast height and stem straightness degree as evaluation indexes,providing genetic gains of 28.69,17.96,and 0.67 %,respectively.The results of variance analysis about wood properties(wood density,fiber length,fiber width,ash content,lignin content,cellulose content,hemicellulose content and holocellulose content)of 208 L.olgensis clones showed there were significant differences(P < 0.01)except for wood density and ash content.The phenotypic coefficient of variation and repeatability of wood properties were 12.09-35.33 % and 0.218-0.930,respectively.The correlation analysis showed the correlation coefficients among growth characteristics and wood properties were mostly not significant.Ten clones(L88,L305,L59,L66,L253,L304,L277,L298,L248,and L293)were selected as excellent clones using wood properties as an evaluation index under a selection rate of 5 %.The genetic gains in wood density,fiber length,fiber width,cellulose content,and hemicellulose content were 4.14,3.64,9.28,6.77,and 9.61 %,respectively.11 SNP sites were selected in the gene PAL,which was related with lignin synthesis.All sites were located in exon including 7 transformational sites and 4 transversion sites,5 silent mutation and 6 nonsynonymous mutation.The genetic distance of PAL between each clone was 0.000-0.035 cM,thereinto,L287 and L102 showed the biggest comprehensive genetic differences.The Pi value of gene PAL was 0.00340,which showed high diversity of PAL.The results of the correlation analysis showed there were 4 SNP sites which were related with lignin content significantly,SNP116,SNP922,SNP1150 and SNP1186.4 SNPs were all nonsynonymous mutation sites.Thereinto,SNP116(T-C),the lignin content of mutation type(CC)was lower than that of wild type(TT).However,SNP922(C-A),SNP1150(A-C)and SNP1186(T-G),the lignin content of mutation types were all higher than that of wild types. |
