基于SSR标记的澳洲坚果种质资源遗传多样性分析

澳洲坚果原产于澳大利亚亚热带雨林,是我国新兴的重要经济作物,其种质资源丰富,但遗传背景复杂,亲缘关系混乱。开展澳洲坚果种质资源遗传多样性分析,可拓展澳洲坚果种质资源创新利用途径,有效加快澳洲坚果育种进程。形态表型分析是最早用于种质鉴定和管理的标记之一,但易受环境因素影响。DNA分子标记技术在种质资源鉴定、遗传多样性分析中克服了传统表型分析易受环境影响的缺点。本研究采用9对高多态性SSR引物对91份国外引进以及自主选育品种(品系)澳洲坚果种质进行遗传多样性分析。结果表明,共扩增出73个等位基因位点,平均等位基因8个,平均基因多样性为0.689,平均杂合度为0.578,多态性信息含量PIC为0.453~0.792,平均值为0.659,表明91份澳洲坚果具有较高的多态性。UPGMA聚类分析表明,在遗传距离为0.33处,将91份澳洲坚果分为2大类,且其亲缘关系与地理来源无显著相关性,与主成分分析、Structure分析结果一致。本研究供试澳洲坚果材料群体内遗传变异显著高于群体间变异,且遗传成分来源单一,遗传结构较为简单。本研究为澳洲坚果种质的有效利用以及核心种质构建提供理论基础,为进一步加速澳洲坚果种质遗传改良以及分子辅助育种奠定基础。

Genetic Diversity Analysis of Macadamia Germplasm Resources by SSR Markers

Macadamia,derived from the Australian subtropical rainforest,is a recently domesticated nut crop in China.Macadamia is rich in germplasm resources.However,the genetic background of Macadamia is complex and the genetic relationship is unclear.The genetic diversity analysis of Macadamia germplasm resources can expand the innovative utilization of Macadamia and effectively improve the Macadamia breeding process.Morphological traits are among the earliest markers used in germplasm characterization and management.However,phenotypic analysis is easily affected by environmental factors,resulting in deviation in the results.DNA molecular marker technology overcomes the shortcomings of traditional phenotypic analysis vulnerable to environmental impact in germplasm resource identification and genetic diversity analysis.The genetic diversity of 91 Macadamia germplasm introduced from abroad and self-breeding varieties(lines) was analyzed by 9 simple sequence repeat(SSR) loci in this study.The results showed that a total of 73 alleles were amplified by 9 pairs of SSR primers,with average of 8 per marker.The average genetic diversity was 0.689.The average heterozygosity was 0.578.The polymorphic information content(PIC) of each locus varied from 0.453 to 0.792 with an average of 0.659,indicating that Macadamia germplasm had high genetic diversity.UPGMA cluster analysis showed that the tested Macadamia resources could be divided into two groups at the genetic distance of 0.33.The first category includes all Macadamia tetraphylla species,Nelmak1-1,Nelmak1-2 and HAMC14,with a total of 19 germplasms.The second category contains 72 germplasms,mainly the cultivated varieties in Australia and Hawaii and self-breeding varieties(lines) in China.There was no significant correlation between genetic relationship and geographical origin.The results were consistent with population genetic structure analysis and principal component analysis.For population genetic structure analysis,Bayesian clustering modelling was executed in the Structure software using data generated by SSR marker-based profiling and diversity analysis of 91 Macadamia accessions.The highest log-likelihood was performed which provided the maximum peak at K=2,indicating that all genotypes represent two distinct clusters.In addition,the results showed that the genetic components of Macadamia germplasm were single and the genetic structure was relatively simple.AMOVA analysis showed that the genetic variation within Macadamia populations was 90% and that among populations was 10%,indicating that the genetic variation of Macadamia used in this research within population was significantly higher than that among population.This study provides a theoretical basis for the effective utilization of Macadamia germplasm and the construction of core germplasm.In addition,we therefore aimed to use the SSR markers to accelerate genetic improvement in Macadamia breeding program.These results lay a foundation for molecular marker-assisted breeding in Macadamia.