Characterization of the floral traits, pollen micromorphology and DNA barcoding of the edible flowers from three basil taxa (Lamiaceae)

Abstract

The edible flowers sector is expanding due to the popularity and uses in culinary recipes of different species. In particular, flowers of Ocimum basilicum L. and related taxa are increasingly used for their aromas and nutritional value. However, there is limited information regarding their morphological characteristics and molecular profiles, which are both important to perform a quality control of food, and to avoid contaminations. Hence, our aim was the study of three basil taxa (O. basilicum ‘Cinnamon’, O. basilicum ‘Blue Spice’, and the hybrid O. × africanum Lour.) to obtain data useful for taxa identification and to understand which traits could be linked to their chemodiversity. The plants were grown in a greenhouse starting from seeds. Flowers were collected at anthesis; the morphology of calyxes, corolla and pollen grains was characterized; DNA barcoding analyses were performed. All taxa were identified only as O. basilicum by molecular analyses, but two haplotypes were distinguishable. All taxa were identifiable due to the presence/absence of specific glandular trichomes, and by pollen size and number of colpi. ‘Cinnamon’ and O. × africanum showed more morphological affinities to each other, but histochemical analyses suggested the separation of the three taxa. Pollen grains from ‘Cinnamon’ had the smallest diameter in polar view and were hexacolpate, while ‘Blue Spice’ pollen showed the highest diameter with grains being hexacolpate/octacolpate, similarly to O. × africanum. Our interdisciplinary study provides the first information for authenticating these basil cultivars in packaged products for human consumption.