In vitro organogenesis and growth of Ocimum basilicum ‘Genovese’ (basil) cultivated with growth regulators

Abstract

Genovese basil is a medicinal plant broadly used in medicine, perfumery, and cooking. In this study, the in vitro organogenesis and growth of Genovese basil seedlings are evaluated through the effect of growth regulators applied in different doses. Eight treatments were performed combining different concentrations of auxins and cytokinins, plus one control. At the end of the trial, growth characteristics of the seedlings were measured, and anatomical sections of the leaves and stems of the basil were prepared. The results demonstrated the need for cytokinins to increase the number and length of shoots and the length of roots. The treatment with 0.2 mgL-1 benzyl aminopurine (BAP) mgL-1 demonstrated the best result. The combined action of auxins and cytokinins increased fresh and dry masses of roots (0.3 mgL-1 BAP + 0.6 mgL-1naphthaleneacetic acid [NAA]). Partial changes in the leaf architecture as well as a reduction in the thickness of the palisade and lacunar parenchyma were observed, especially in treatment T8 (0.4 mgL-1 BAP+ 0.2 mgL-1NAA). In addition, all treatments with regulators presented adventitious roots in the stem, originating from inner-stem cells or vascular tissues. The formation of callus at the base of the plants and the occurrence of abnormal seedlings indicate that Genovese basil was responsive to the action of the growth regulators, although other factors regarding the medium could influence such responses. The growth regulators also function in the expression of genes linked to the stretching process (auxins) and cell proliferation (cytokinin).