毛白杨木材形成功能基因内SSR标记的开发及评价

Development and Evaluation of Simple Sequence Repeat (SSR) Loci from Functional Genes Involved in Wood Formation in Populus tomentosa

利用直接测序法开发木材形成功能基因内一套新的核基因组SSR标记。通过对参与木材形成的16个基因在40个毛白杨基因型个体中的序列比较分析,共检测到20个SSR多态性位点。在毛白杨自然群体中,SSR多态性位点的碱基重复呈现出二碱基、三碱基、五碱基、六碱基与七碱基形式,基元重复次数变异范围为2～34次,其中以二碱基重复的位点较多,占总数的55.0%。在此基础上,依据SSR位点两侧的保守序列,设计20对SSR位点PCR扩增引物对。利用设计的引物检测开发的SSR位点在杨属内15个基因型个体中PCR扩增的有效性及SSR位点的保守性。PCR扩增结果显示,90.0%的SSR位点能够在杨属至少2个派内有效扩增,每对引物组合可检测到SSR多样性位点数为3～9个,平均5.3个。开发的这些SSR位点在功能基因内不同区域的分布频率不同。

Species-specific simple sequence repeat（SSR）markers are desirable for genetic studies and to harness the potential of MAS-based breeding for genetic improvement of wood fiber traits in trees.In this study,we report that a set of new polymorphic nuclear SSR markers were developed and characterized in Populus tomentosa by means of direct sequencing of functional genes involved in wood formation.A total of 20 polymorphic SSR loci were identified within 16 genes from 40 unrelated individuals in P.tomentosa.The SSR types of di-,tri-,penta-,hexa-,and hepta-nucleotide repeats and motifs repeats varied from 2 to 34 were displayed,with dinucleotide SSRs being the most frequent,accounting for 55.0% of the total loci in the natural population of P.tomentosa.Twenty primer pairs for PCR amplification SSR loci were designed based on the conservative flanking sequences of SSR loci.The efficiency and conservation of SSR loci were tested among 15 individuals under genus Populus.The PCR amplification exhibited an average of 90.0% conservation in at least two groups under genus Populus,and the number of alleles produced ranged from 3 to 9,with an average of 5.3 alleles per locus.Furthermore,the SSR loci were non-randomly distributed within different regions of functional genes.The gene-based SSR markers developed here would provide a powerful tool for MAS breeding of new germplasms with desirable wood fiber traits in P.tomentosa,and have theoretical and practical significance in tree breeding.