Possibility of utilizing Inter Simple Sequence Repeat regions, bark powder morphology and floral morphometry to characterize the <em>Cinnamomum</em> species in Sri Lanka

Abstract

The genus Cinnamomum of the family Lauraceae is an economically important crop. The Ceylon cinnamon (Cinnamomum verum syn. C. zeylanicum) has an exceptional position in the global cinnamon market. In addition to the cultivated species, Sri Lanka is home to seven endemic wild Cinnamomum species, C. capparu-coronde, C. citriodorum, C. dubium, C. litseifolium, C. ovalifolium, C. rivulorum, and C. sinharajaense. Nevertheless, the species delimitation has not been successful with some morphometric and molecular traits. Therefore, this study focused on molecular characterization with an Inter Simple Sequence Repeats (ISSR) nuclear marker, floral morphometric characteristics, and microscopy of the powered bark of Cinnamomum species reported in Sri Lanka. According to the results four polymorphic ISSR regions resulted in an average of 83.7% polymorphism among all collected species, suggesting considerable polymorphism. The bark fiber size of the cultivated species is different from the studied wild species and could be used as a key to identify adulterants during export. The cultivated cinnamon, C. verum and two wild species (C. sinharajaense, and C. capparu-coronde) have considerably larger flowers compared to other species. Moreover, floral traits such as flower colour and shape could differentiate species C. sinharajaense and C. capparu-coronde. The Scanning Electron Microscopy (SCM) of pollen showed that the pollen size, spine length, interspinal distance, and spine ornamentation significantly contribute to species variation, and such variations need to be studied comprehensively. Nevertheless, the phylogeny of Cinnamomum species could not be completely resolved using ISSR regions, bark powder morphology, and floral morphological traits assessed and suggested for further studies.