Department of Botany and Microbiology, Faculty of Science, Zagazig University, Zagazig, 44511, Egypt.
J Plant Res. 2024 Nov;137(6):967-984. doi: 10.1007/s10265-024-01566-9. Epub 2024 Aug 15.
Hibiscus is a charismatic genus of the Malvaceae family that is noted for its diversity, lacking identifiable characteristics for distinguishing its various species. Therefore, there is an urgent need to develop authentication methods for genus delimitation and species delineation. The present study aims to discern the taxonomic relationships between the well-known, globally familiar, and economically important five Hibiscus species, namely: H. × rosa-sinensis, H. sabdariffa, H. schizopetalus, H. syriacus and H. tiliaceus based on traditional morphological and anatomical characteristics compared to the contemporary chemotaxonomy. In this context, the leaf-based methanolic extracts of the studied species were analyzed by Gas Chromatography-Mass Spectrometer (GC-MS) to estimate their secondary metabolites similarity. In addition, selected qualitative morphological and anatomical traits including leaf venation patterns, epidermal micromorphology, stomata types and trichomes diversity, petiole serial sectioning (outline, adaxial groove features, vasculature traces arrangement), and midrib characteristics of the studied species were investigated. The results of both chemotaxonomy and traditional taxonomy exhibited a remarkable agreement in the delineation of the five studied species. Specifically, the chemotaxonomy-based dendrogram separates the studied species into two main clusters with the H. sabdariffa as an outlier species in a single cluster and the remaining four species as another cluster with variant distances in its similarity indices. Similarly, the traditional morphological and anatomical characteristics revealed distinct traits for H. sabdariffa compared to the remaining four species. The findings of this study highlight the significance of integrating the structural features with phytochemicals profiling as a potential approach that could be harnessed for the delineation of the taxonomically challenging Hibiscus genus.
木槿是锦葵科的一个魅力四射的属，以其多样性为特征，缺乏可识别的特征来区分其不同的物种。因此，迫切需要开发用于属界定和种划分的鉴定方法。本研究旨在根据传统形态学和解剖学特征以及现代化学分类学，区分广为人知、全球熟知且经济重要的五个木槿物种，即：H. × rosa-sinensis、H. sabdariffa、H. schizopetalus、H. syriacus 和 H. tiliaceus。在这种情况下，对研究物种的基于叶片的甲醇提取物进行气相色谱-质谱分析 (GC-MS)，以估计其次生代谢物的相似性。此外，研究了包括叶脉模式、表皮微观形态、气孔类型和毛状体多样性、叶柄连续切片（轮廓、腹面凹槽特征、脉管束排列）以及研究物种中脉特征在内的选定定性形态和解剖特征。化学分类学和传统分类学的结果在五个研究物种的划分上表现出显著的一致性。具体来说，基于化学分类学的系统发育树将研究物种分为两个主要聚类，其中 H. sabdariffa 是一个单独聚类中的异常种，其余四个物种是另一个聚类，其相似性指数的差异较大。同样，传统形态学和解剖学特征揭示了 H. sabdariffa 与其余四个物种相比具有明显的特征。本研究的结果强调了将结构特征与植物化学特征相结合作为一种潜在方法的重要性，这种方法可用于具有挑战性的木槿属的分类。
