地黄新变型金黄花地黄的表型和分子鉴定

Phenotype and molecular identification of Rehmannia glutinosa f. aurum

关键词:  金黄花地黄, 花青素, 环烯醚萜苷, 形态特征, 分子鉴定

Key words:  Rehmannia glutinosa f. aurum, anthocyanin, iridoid glycosides, morphological features, molecular identification

摘要:

该文报道了玄参科地黄属植物地黄(Rehmannia glutinosa)的一新变型——金黄花地黄(R. glutinosa f. aurum)的表型和分子鉴定结果。基于形态解剖特征观察、总花青素苷与5种环烯醚萜苷类成分含量测定、文献梳理、分子鉴定和遗传分析,确定其分类学地位、应用价值和遗传特性。结果表明:(1)金黄花地黄区别于原变型的主要特征为花冠筒金黄色,花冠裂片黄白色,花冠中的总花青素苷含量低。(2)多拷贝核基因ITS和单拷贝核基因R255进化分析均显示金黄花地黄与地黄聚在同一分支,为二者应属于同一物种提供了有力证据。(3)金黄花地黄叶和块根中的梓醇含量分别为5.15%和4.51%,说明该新变型富含环烯醚萜苷。(4)将金黄花地黄与地黄栽培品种HF进行杂交,其杂交种F₁代植株(HF/f. aurum)的花冠均为紫红色,进而以金黄花地黄为轮回亲本与F₁代植株进行回交,获得的种子为BC₁F₁代,并从BC₁F₁群体(HF/f. aurum//f. aurum)中分离到紫色花冠和金黄色花冠的植株,二者的分离比为4.17:1。综上,该研究发现的金黄花地黄为地黄的一个变型,花青素合成受阻是其花色形成的主要原因,叶和块根中均含有丰富的环烯醚萜苷,遗传上可能受2对隐性基因控制,这为金黄花地黄种质资源的开发、保护和利用提供了科学依据。

Abstract:

This study reports the results of phenotype and molecular identification of a new forma of Rehmannia glutinosa(Scrophulariaceae), namely R. glutinosa f. aurum. The taxonomic status, application value and genetic characteristics of this newly discovered forma were determined based on a combination of morphological and anatomical observations, quantification of total anthocyanins and five iridoid glycoside components, a comprehensive literature review, molecular identification and detailed genetic analysis. The results were as follows:(1)R. glutinosa f. aurum could be distinguished from the typical form a mainly on the basis of its golden-yellow corolla tube, yellowish-white corolla lobes, and a relatively low content of total anthocyanin glycosides in the corolla.(2)Phylogenetic analysis results of both the multi-copy nuclear gene ITS and the single-copy nuclear gene R255 showed that R. glutinosa f. aurum and R. glutinosa were in the same clade, providing a strong evidence that these two forms belong to the same species.(3)The catalpol contents in the leaves and tuberous roots of R. glutinosa f. aurum were measured to be 5.15% and 4.51%, respectively, indicating that this new forma was rich in iridoid glycosides.(4)R. glutinosa f. aurum was crossed with the cultivated variety HF of R. glutinosa. All resulting F1 generation plants(HF/f. aurum)exhibited purple-red corollas. Subsequently, backcrossing was performed using R. glutinosa f. aurum as the recurrent parent and the F1 hybrid plants(HF/f. aurum)as the donor parent and obtained seed was BC1F1 generation. In the resulting BC1F1 population(HF/f. aurum//f. aurum), plants with purple corollas and plants with golden-yellow corollas segregated at a ratio of 4.17:1. In conclusion, R. glutinosa f. aurum found in this study represents a forma of R. glutinosa. The inhibition of anthocyanin biosynthesis is the primary reason for its unique flower coloration. Both its leaves and tuberous roots contain abundant iridoid glycosides, which are of potential medicinal value. Genetically, the flower color trait of this forma is likely controlled by two pairs of recessive genes. Taken together, these findings provide a solid scientific basis for the further development, conservation, and utilization of the germplasm resource of R. glutinosa f. aurum.