化龙山七筋姑种内二倍体与四倍体表型分化分析

Phenotypic Differentiation between the Diploidy and Tetraploidy of Clintonia udensis in Hualong Mountains

七筋姑(Clintonia udensis Trautv.et Mey.)属百合科(Liliaceae)七筋姑属(Clintonia Raf.),多年生草本,具有二倍体(2n=14)和四倍体(4n=28)两种倍性。在陕西化龙山地区,二倍体主要分布在南坡海拔2450 m处,四倍体主要生长在北坡海拔1900 m左右,成为研究种内多倍体分化的理想材料。该研究从七筋姑营养和繁殖系统出发,研究其不同倍性的表型分化,揭示不同倍性的生态适应特征,为阐明七筋姑种内多倍体的演化提供线索。研究表明:(1)在根、茎、叶、花、果实、种子的11个性状中,二倍体的果实体积性状最为稳定(CV=0.02),叶长性状遗传多样性最高(CV=0.85);四倍体中果实体积性状也最为稳定(CV=0.06),而花数量性状多样性最高(CV=0.42)。(2)四倍体的果实体积平均值明显高于二倍体,但种子数量平均值显著少于二倍体,果实体积和种子体积性状在不同倍性间的分化占比最高(Vst=0.69)。(3)四倍体营养器官表型性状的遗传变异丰富度低于二倍体,其平均变异系数(CV=0.16)小于二倍体的变异系数(CV=0.44);在繁殖系统表型性状中,四倍体的遗传变异丰富度高于二倍体,平均变异系数(CV=0.30)大于二倍体(CV=0.26)。(4)显著性分析表明,二倍体与四倍体表型性状差异显著(P<0.05),而繁殖系统性状在不同倍性间无显著差异(P>0.05);PCA分析同样显示二倍体与四倍体间存在明显差异。四倍体显著的表型差异是对低海拔环境长期适应的结果。

Clintonia udensis belongs to the genus Clintonia of Liliaceae,is a perennial herb with two cytotypes,the diploidy(2n=14)and tetraploidy(4n=28).In Hualong Mountains of Shaanxi Province,the diploidy mainly distributes at 2450 m in the south slope,while the tetraploidy mainly grows at 1900m in the north slope,which making them as an ideal material for the study of intra-specific polyploid differentiation.In this study,based on the nutritional and reproductive system of C.udensis,we would analyze the phenotypic differentiation of different cytotypes,reveal the ecological adaptation characteristics of the two cytotypes,and provide some clues for the evolution of C.udensis's polyploid.The results showed that:(1)the fruit volume of the diploidy was the most stable(CV=0.02),and the genetic diversity of the leaf length was the highest(CV=0.85)among eleven traits.Meanwhile,the fruit volume was also the most stable one in the tetraploidy(CV=0.06),while the flower quantitative had the highest diversity(CV=0.42).(2)The average of fruit volume for the tetraploidy was significantly higher than that of the diploidy,but the average of seed number was significantly lower than that of the diploidy,and the differentiation proportion of fruit and seed volume between different ploidy types was the highest(Vst=0.69).(3)On the other hand,the genetic variation of the phenotypic traits for the tetraploidy nutritional organs was lower than that of the diploidy,and the average coefficient of variation(CV=0.16)was also lower than that of the diploidy(CV=0.44).For the reproductive system,the genetic variation of the tetraploidy was higher than that of the diploidy,and the mean variation coefficient(CV=0.30)was higher than that of the diploidy(CV=0.26).(4)According to the significant,there was a differentiation occurred in phenotype traits between the diploid and tetraploid(P<0.05).However,no significant difference was found in the reproductive system between the different ploidies(P>0.05).PCA analysis also showed significant difference between the diploidy and tetraploidy.The significant phenotypic difference of the tetraploidy would be resulted from the long-term adaptation to low altitude environment.