Morphology of Peltate Glandular Trichomes in Healthy Leaves of Field-Grown Sweet Basil Plants, Propagated Plantlets In vitro, and Naturally Infected by Alfalfa Mosaic Virus

Abstract

The variations in the peltate glandular trichome (GT) structures on the leaves of healthy Ocimum basilicum and infected ones with the Alfalfa mosaic virus (AMV) in the open field, as well as the propagated plantlets under in vitro conditions, were examined using scanning electron microscopy (SEM). Infected basil leaves with AMV showed severe malformations of peltate GT on leaves, which differed structurally by viral infection. A double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) was used to assess the elimination of AMV using three apical meristem sizes (0.2, 0.3, and 0.4 mm). All the used sizes produced AMV-free O. basilicum explants (100%). The apical meristem sizes (0.3 and 0.4 mm) had a pronounced effect on the maximum establishment or ratio of survival rates (76.6 and 80 %). The AMV-free plants derived from the meristem size (0.4 mm) were multiplied on MS medium supplemented with 0.5 mg/l of BA and 0.5 mg/l of JA. Micrographs of in vitro cultures displayed broad secretory glands and trichomes of type non-glandular, indicating somewhat significant homogeneity among the adaxial and abaxial leaf surfaces of the regenerated plants in vitro and the healthy basil leaves in the open field. In conclusion, GT structure in diseased leaves might serve as a sign of viral disease stress. Based on the findings of this study, the food, cosmetics, and pharmaceutical industries also benefit significantly from the in vitro method.