西南地区野生刺梨的遗传多样性和遗传结构研究

Genetic diversity and structure of wild Rosa roxburghii in Southwest China

关键词:  刺梨, 单拷贝核基因, 叶绿体基因, 遗传多样性, 遗传结构

Key words:  Rosa roxburghii, single-copy nuclear gene, chloroplast gene, genetic diversity, genetic structure

摘要:

为了探究西南地区野生刺梨(Rosa roxburghii)的遗传多样性和起源演化,该研究基于2段单拷贝核基因(GAPDH和ncpGS)和3段叶绿体基因(atpF-trnH、trnL-trnF和trnG-trnS)的拼接序列,对刺梨27个野生居群共320个个体进行PCR扩增和测序,并用相关软件对测序结果进行分析。结果表明:(1)在单拷贝核基因和叶绿体基因水平上刺梨均表现出较低的遗传多样性(scnDNA: Hd=0.469 2, π=0.000 49; cpDNA: Hd=0.653 4, π=0.000 65),并且不同居群间存在较大差异。(2)分子方差分析(AMOVA)结果均显示,遗传变异主要发生在居群内,表明居群内的变异是野生刺梨遗传变异的主要来源,居群间存在明显的遗传分化( cpDNA:F_ST=0.336 47,G_ST=0.273,N_ST= 0.308; scnDNA:F_ST=0.094 87,N_ST=0.076,G_ST=0.056),刺梨的分布不具有明显的谱系地理结构(P>0.05)。(3)中性检验 Tajima's D值均为不显著负值,符合中性进化模型。Fu's Fs值均为显著负值,结合失配分析曲线,推测刺梨种群在小范围内经历过扩张,但总体上维持稳定状态。(4)根据单倍型多样性得出,毕节地区的居群遗传多样性水平较高并且拥有丰富的单倍型,推测可能为冰期避难所,因此应对其实施就地保护。对于拥有特殊性状和特有单倍型的居群也应采取优先保护措施。该文为野生刺梨资源保护和遗传育种提供了一定的参考价值。

Abstract:

In order to study genetic diversity and the origin of wild Rosa roxburghii in Southwest China and provide some bases for its utilization and protection. A survey was based on the splicing sequences of two single-copy nuclear genes(GAPDH and ncpGS)and three chloroplast genes(atpF-trnH, trnL-trnF and trnG-trnS). The individuals of 320 wild R. roxburghii from 27 wild populations in China were amplified, sequenced by PCR. After that, the sequencing results were analyzed with relevant software. The results were as follows:(1)Low genetic diversity levels were found in R. roxburghii of single-copy nuclear gene(Hd=0.469 2, π=0.000 49)and chloroplast gene(Hd=0.653 4, π=0.000 65). But there were significant differences among different populations.(2)Analysis of molecular variance(AMOVA)showed that the genetic variation almost occured within populations, which indicated that population variation was the main source of genetic variation in wild R. roxburghii. It existed obvious genetic differentiation among populations(cpDNA: F_ST=0.336 47, G_ST= 0.273, N_ST= 0.308; scnDNA: F_ST=0.094 87, N_ST=0.076, G_ST=0.056). The distribution of R. roxburghii did not have obvious phylogeographical structure(P>0.05).(3)Tajima's D value of neutral test was insignificantly negative value, indicating that R. roxburghii populations conformed to neutral evolution model. Fu's Fs value was significantly negative, combining the result of mismatch analysis curve, deducing that R. roxburghii populations had an expansion within a small range before. But generally, they remained stable.(4)According to the haplotype network, the populations of the Bijie region not only presented higher genetic diversity, but also had a lot of haplotypes. Therefore, the Bijie region was speculated to be one of the refuges of ice age. Therefore, they were supposed to be carried out the strategy of local protection. The populations with special traits and unique haplotypes shall be protected to adopt a priority protection approach. The survey is expected to provide a reference for wild R. roxburghii of the resource protection and genetic breeding.