美洲黑杨与小叶杨杂交F1代扦插无性系苗生长性状动态分析

Analyses of dynamic growth traits of the stecklings from the F1 hybrid progeny of Populus deltoides×P.simonii

【目的】探讨美洲黑杨(Populus deltoides)×小叶杨(P.simonii)F1代无性系苗期生长变异,发现F1代无性系生长性状变异规律,为后期在统计分析方面开展杨树数量性状基因定位研究提供重要的参考依据。【方法】以南京林业大学下蜀林场美洲黑杨×小叶杨F1代无性系为研究材料,采用完全随机区组设计,对苗高和地径生长性状在扦插后2年的不同时期进行测量,利用R语言和SPSS统计软件进行遗传变异分析和评价。【结果】苗高和地径在区组间、无性系间、区组与无性系交互作用间均达极显著差异水平。苗高的变异系数2017年由31.96%变为22.04%,2018年稳定在20%左右,地径的变异系数在2017、2018年两个年末分别为26.66%和26.20%。苗高和地径在两年中多个时间点的重复力具有一定波动性,苗高的重复力2017年由0.69逐渐降低到0.41,2018年又回升到近0.60;地径的重复力在2017年末较低,2018年末变为较高的水平(0.59)。根据无性系效应估计值,每年的无性系大致可分为8类,每类的均值效应具有独特的变化趋势,2017年有CL2、CL6、CL7和CL8共4类的均值效应随时间递增,而CL1、CL3、CL4、CL5类则减少;2018年除CL8类的均值效应增加外,其他7类基本是平稳的,但是类间的效应差异较大。【结论】所调查的随机区组无性系试验林的苗高和地径生长变异较大,遗传水平上差异性在不同生长期有其独特性,所建立的杨树无性系随机区组试验林为杨树数量性状基因(QTL)定位研究提供很好的遗传作图材料。

【Objective】This study aimed to investigate the variation in the growth traits of clones from the F1 progeny of Populus deltoides×P.simonii to facilitate the establishment of statistical models for detecting quantitative trait loci(QTL)using such clonal materials.【Method】A randomized block experiment was designed to test clones from the F1 hybrid population.Tree height and ground diameter were measured for each clonal individual at multiple time points in 2017 and 2018.The statistical software SPSS was used to perform the variation analysis of the growth traits with linear mixed models,while an R package was used for a clustering analysis of clonal effects estimated from the linear models.【Result】The effects of tree height and ground diameter were significantly different among the blocks,among the clones,and among the interactions of blocks and clones.The phenotypic coefficient of variation for tree height varied from 31.96%to 22.04%in 2017,and this index was maintained at 20%in 2018.The coefficient of variation for ground diameter was 26.66%and 26.20%in 2017 and 2018,respectively.The repeatability of both tree height and ground diameter varied at multiple time points in the two years.The repeatability of tree height gradually decreased from 0.69 to 0.41 in 2017 but increased to nearly 0.60 in 2018.The repeatability of ground diameter was low in 2017 but increased to 0.59 in 2018.According to the estimates of clonal effects at different time points,the clones were roughly clustered into eight groups,in each of which the mean effects varied uniquely over time.The clonal mean effects for the four clusters in 2017 reduced over time,but for the other four clusters,the means increased.Although the mean effects within clusters in 2018 varied smoothly,the differences between clusters expanded.【Conclusion】In summary,the tree height and ground diameter of the clones in the randomized block experiment displayed a great variation,especially at the genetic level at different growth stages over the two years.This provides important evidence for creating unique statistical models for mapping QTLs using these clonal experimental materials.