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兜兰属通用SSR分子标记的开发及其应用

Development and application of universal SSR molecular markers in Paphiopedilum

  • 摘要: 本研究以“多物种转录组同源序列设计法”代替传统的“单一物种转录组序列设计法”,根据同色兜兰(Paphiopedilum concolor (Bateman) Pfitz.)和带叶兜兰(P. hirsutissimum (Lindl. ex Hook. f.) Stein)的转录组同源序列开发SSR分子标记,并在兜兰属植物中进行验证。结果显示:在兜兰属两个物种转录组的同源序列中,共识别出SSR位点7 627个。其中,单核苷酸重复为主要类型,占47.66%,其次为二核苷酸和三核苷酸,分别占37.35%和14.10%。基于此,共开发出5 098对SSR引物。从中筛选并合成了30对SSR引物,其中19对引物在27个兜兰属植物中的扩增率为100%,有效等位基因数(Ne)为4~14,观测杂合度(Ho)和期望杂合度(He)分别为0.074~0.592和0.443~0.890;多态性信息含量(PIC)为0.406~0.873,89.47%的SSR标记多态性信息含量大于0.5。系统发育分析结果表明,遗传距离为0.74时,27个兜兰属植物可分为3大类,19个SSR标记成功区分了每个种和品种。综上,本研究开发的兜兰属通用SSR标记具有100%可转移性和高度多态性,可在兜兰属的种质资源鉴定、遗传分析和资源保护中发挥重要作用。

     

    Abstract: In this study, a multi-species transcriptome-based homologous sequence approach was employed to improve the efficiency and transferability of simple sequence repeat (SSR) molecular marker development in Paphiopedilum, replacing conventional single-species strategies. Homologous transcriptomic sequences from P. concolor (Bateman) Pfitz. and P. hirsutissimum (Lindl. ex Hook. f.) Stein were used to identify SSR loci and design primers, followed by empirical validation across diverse Paphiopedilum taxa. Results identified a total of 7 627 SSR loci, dominated by mononucleotide repeats (47.66%), with dinucleotide (37.35%) and trinucleotide (14.10%) repeats comprising the remainder. From these loci, 5 098 primer pairs were generated, of which 30 were selected, synthesized, and tested. Nineteen primer pairs achieved a 100% amplification rate across the 27 surveyed Paphiopedilum species and cultivars. These validated markers exhibited high levels of polymorphism, with the number of effective alleles (Ne) ranging from 4 to 14, observed heterozygosity (Ho) between 0.074 and 0.592, expected heterozygosity (He) between 0.443 and 0.890, and polymorphism information content (PIC) between 0.406 and 0.873. Notably, 89.47% of the SSR markers showed PIC values exceeding 0.5. Phylogenetic reconstruction based on these markers resolved all 27 Paphiopedilum species/cultivars into three major clades at a genetic distance of 0.74, with clear species- and cultivar-level discrimination. In conclusion, these broadly transferable, highly polymorphic SSR markers establish a robust molecular framework for Paphiopedilum, enabling precise germplasm discrimination, rigorous genetic analysis, and informed conservation management across the genus.

     

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