麻花艽和管花秦艽( 龙胆科) 之间自然杂交类型的分子验证

野外考察发现麻花艽( Gentiana straminea Maxim. ) 和管花秦艽( G. siphonantha Maxim . ex Kusn. ) 同域分布时存在大量形态位于二者之间的个体。经形态变异研究后发现它们可能是这两个物种之间的杂交后代。对两个亲本种以及假设杂交群体共55 个个体的核糖体ITS 序列和叶绿体trnS-G 序列的分析结果表明:中间形态个体是麻花艽和管花秦艽的自然杂交后代。此外分析了两个亲本种以及杂交群内个体间trnS-G和ITS 序列的变异状况以及分子标记结果与形态鉴定不一致的可能原因; 指出可能是杂交诱导的叶绿体基因组重组以及早期物种分化中的谱系筛选不彻底等原因造成了亲本种群体内序列变异的多样化。

Confirmation of Natural Hybrids between Gentiana straminea and G. siphonantha (Gentianaceae) Based on Molecular Evidence

A few individuals with intermediate morphology always appear in the sympatric distributions of Gentiana straminea and G. siphonantha. These intermediate individuals were hypothesized to be the hybrids of two species after a careful evaluation of their morphological characters. To test this hypothesis, the sequence comparison of the internal transcribed spacer ( ITS) regions of nuclear ribosomal and trnS (GCU)- trnG (UCC) intergenic spacer region of the chloroplast DNA from Gentiana straminea, G. siphonantha, and the putative hybrids was performed. The results suggested that mostintermediate individuals were the natural hybrids between G. straminea and G. siphonantha. In addition, we examined the sequence variation among the individuals of both parent species and provided the possibility leading to the incongruent identification to some individuals by morphology and molecular evidences respectively. The intraspecific diversification of DNA fragments within both parent species and their high variability in hybrid swarms probably resulted from chloroplast genome recombination and incomplete lineage sorting during the early stage of speciation origin of parent species.