粗皮桉近红外光谱差异与其遗传差异间的关系

The Relationship Between Genetic Variations and NIRs Differences of Eucalyptus Pellita Provenances

摸清粗皮桉(Eucalyptus pellita)群体的遗传亲缘关系,对研究桉树杂交育种理论,开发优良新品种具有非常重要的意义。研究意在通过对比粗皮桉种源遗传差异与其光谱差异间的关系,探索近红外光谱(NIRs)技术用于粗皮桉遗传亲缘关系分析的可行性。以粗皮桉天然种源材料为对象,每个种源采集8~12个家系叶样。通过全基因组重测序,基于核苷酸序列差异计算种源间的遗传距离。同时,每个家系选择4~6片健康叶片烘至绝干后,将其粉碎装于透明自封口塑料袋。用手持式近红外仪Phazir Rx (1624)采集样品的NIRs信息。以簇类独立软模式(SIMCA)判别分析统计对比种源到目标种源的光谱距离,并基于NIRs欧氏距离对种源进行层级聚类。以NIRs的PCA因子得分图分析种源间的遗传亲缘关系及其遗传变异。结果显示,粗皮桉新几内亚岛种源间的平均遗传距离为0.186,昆士兰州种源间的平均为0.157,新几内亚岛种源与昆士兰州种源间的平均遗传距离为0.295,明显大于区域内种源间的遗传距离。粗皮桉2大区域种源间的NIRs光谱距离与其种源间遗传距离基本呈正相关关系。基于NIRs的层级聚类在一定程度上印证了种源遗传距离、光谱距离的大小关系,但与其地理距离非完全对应,说明基因交流对粗皮桉群体的遗传亲缘关系有较大的影响。PCA聚类显示,遗传或光谱距离大的种源样本因子得分图存在严重重叠,而遗传或光谱距离小的种源样本因子得分反而会清晰聚类,这表明NIRs信息区分异质样本的敏感性,同时也反映了粗皮桉种源内家系间遗传变异的大小。研究结果表明,NIRs技术能够真实反映粗皮桉种源间的遗传差异,可用于桉树群体遗传亲缘关系及群体内的遗传变异分析,可辅助桉树群体的世代改良研究。

Clarifying the pedigree on Eucalyptus pellita populations is of great significance for studying rules of interspecific hybridization of eucalypt and the development of excellent new eucalypt genotypes. The purpose of the present study was to assess the accuracy and reliability of near infrared spectroscopy(NIRs) used in the analysis of the pedigree of E. pellita populations by comparing the relationship between genetic variations and NIRs differences that. The genetic materials involved natural provenances from the E. Pellita population, fresh leaves of 8~12 families were collected from each provenance. The DNA information of materials was obtained through whole-genome resequencing. Firstly, the genetic distances among provenances were evaluated with the DNA nucleotide sequence differences between samples. Meanwhile, four to six healthy leaves of each sample were placed in a drying ovenuntil completely dry. The dried leaves were milled and then put into a transparent self-sealing plastic bag. A portable NIR device, phazir RX(1 624), was used to take the NIRs information of samples. The NIRs spectral distance between validating provenance and calibrating provenance was estimated with the soft independent modeling of class analogy(SIMCA). Hierarchical clustering was performed for all provenances with NIRs Euclidean distance. PCA scores plots of provenances NIRs demonstrated the pedigree and the genetic variations of provenances. The results showed that the total mean of the genetic distance of provenances from New Guinea Island and Queensland were 0.186 and 0.157 respectively, the total mean of genetic distance between New Guinea Island and Queensland was 0.295, which was higher than that within each separate district significantly. There was a positive correlation between NIRs spectral distance and genetic distance between provenances in two separate districts, but a negative correlation was also found between some provenances of E. pellita. The correlation between genetic distance and NIRs spectral distance was also proved by the NIRs Hierarchical clustering of all provenances. However, the clustering did not completely correspond with their geographical distance of provenances, suggesting that gene flow of some forms greatly affects the genetic relationship among separate districts of E. pellita populations. The PCA score plots demonstrated that PCs plots of some provenances with large genetic distance or NIRs spectral distance would overlap seriously, and PCs plots of some provenances with close genetic distance or NIRs spectral distance would be clustered, which verified the sensitivity of NIRs in the distinguishing of heterogeneous samples, also showed the genetic variation among families inprovenance of E. pellita. All the current study results proposed that NIRs could genuinely reflect the genetic differences among provenances of E. pellita, and could be used to analyze the genetic relationship and genetic variation within eucalypt populations, and could be used to assist the improvement of eucalypts breeding populations in a generation.