Taxonomic treatment of Myrtaceae based on leaf morphology, architecture, foliar oil glands and molecular characteristics

Mohamed, Alsafa Hassan; Abd Allah, Soad Hassan; Hamed, Karima Abd-Elkhalek; Hosney, Nareman Kamal

doi:10.21608/taec.2023.212293.1050

Taxonomic treatment of Myrtaceae based on leaf morphology, architecture, foliar oil glands and molecular characteristics

Document Type : Original Article

Authors

Botany department, Faculty of Science, Ain Shams University,Cairo,Egypt

10.21608/taec.2023.212293.1050

Abstract

The macromorphological characters and lamina vein architecture were examined by the aid of stero microscope. In addition, molecular study using SCoT markers were made on 26 species belonging to 15 genera of family Myrtaceae (nine genera belonging to subfamily Leptospermoideae and six genera belonging to subfamily Myrtoideae) to evaluate such characters in taxa delimitation.

The obtained results revealed that, all studied taxa of Myrtaceae are distinguished by a combination of the following features: simple leaves with entire margin and glandular -punctate or pellucid leaves, while the leaf arrangement, lamina shape, apex and base showed great variation among them. Pinnate simple brochidodromous leaf venation is the most common, although other patterns were also recorded viz. cladodromous, eucamptodromous and craspedodromous. The irregular reticulate tertiary and quaternary vein fabric, presence or absence of an intramarginal vein were frequently observed. The oil glands with various shape, color and distributions were also recorded in all studied taxa except in Corymbia ficifolia and Melaleuca linariifolia. Eight SCoT primers were performed to study the genetic diversity between the studied taxa. The total number of amplified fragments was 125; 119 of them were polymorphic, while the remaining six were monomorphic. The total number of specific markers produced were 19. Only one of them scored for the absence of the band while the other 18 markers scored for the presence of unique band. Only ten taxa scored specific markers. Seven primers produced specific markers with largest number generated by primer SCoT 5 (six markers) and the lowest number generated by SCoT 2 and SCoT 5 (one marker for each), while primer SCoT 4 didn’t reveal any specific markers.

The obtained results were analyzed numerically (by PAST4 software) to construct three dendrograms; the leaf morphological based characters, the molecular based analysis and combined one. The combined resulted dendrogram and macromorpholgical based one grouped all 13 species of studied berry fruited Myrtoideae with some capsular fruited Leptospermoideae, while the remaining of studied capsular fruited species in other group. This result to some extent supports the concept of classify Myrtaceae into two subfamilies Leptospermoideae and Myrtoideae.

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