| Leaf shape is an important factor in response to environmental changes and is also one of the main driving forces for plant evolution.In recent years,despite an increasing interest in the field that leaf shape traits have long been one of the evolutionary developmental forces in plant.But there are few research that systematically investigate the intricate genetic architecture,the effect of environmental factors as well as the interactive mechanism between them by means of quantitative methods.Populus sechuanica var.tibetica have been used as an important species for studying ecological and evolutionary problems because of its good altitude environmental adaptability.We plant 260 Populus sechuanica var.tibetica natural population individuals which originated from two different altitude areas in a common garden.And the leaves have been used as the research object,the crucial genes inducing leaf shape variation were identified in two altitude subpopulation by Elliptic Fourier Equation and gene mapping.Meanwhile,this study also analyzed the leaf shape differences between two different origins under the impact of the same gene.The results showed that:(1)It is determined that the goodness of fitting of the fourth-order elliptic Fourier parameters to the leaf shape is over 95%,and the fitting condition is good.It is judged by the AIC curve:70 blade edge points can better reflect the true shape of the blade and meet the effectiveness of the model.(2)A total of 66 QTLs significantly associated with leaf-shaped variation were obtained by shape gene mapping(including 28 shape QTL of high type and 38 shape QTL of low type).And the average leaves shape of different genotypes exist differences under shape QTL control,the average leaf shape of the AA genotype is more elongated than the aa genotype,and the latter is approximately oval.The average leaf shape of Aa is between the twice.At the same time,there is a significant gene in both altitude types,which is located at the 36312745 position on chromosome 1.(3)At the same shape QTL of the two altitude types,for the average leaf of the genotype AA,the leaves originated from the high altitude region are long and narrow,resembling an ovate-lanceolate shape,which is different from oval-shaped leaf under low altitude.The average leaf shape of the other two genotypes was not significantly different.(4)The biological functions of 16 QTL were obtained by gene annotation,and two genes were closely related to leaf development,including CUC and TCP genes,which were located on chromosome 1,LOC18095543 gene and chromosome 4,LOC18098300 gene,respectively.In a word,this study found some key genes affecting leaf shape variation,and reveal that profound effects on shape variation from different altitude conditions,it providing a new perspective for research on plant leaf evolution and development. |
