Effects of Brassinolide with Naphthalene Acetic Acid on the Formation of Adventitious Roots, Trichome-Like Roots and Calli from Cultured Tobacco Leaf Segments, and the Expression Patterns of CNT103

Abstract

We treated cultured tobacco leaf segments with brassinolide (BL) and naphthalene acetic acid (NAA) and determined that optimum concentrations of NAA for adventitious root, trichome-like root, and calli formation were, respectively, 10−6, 10−5, and 10−4 M. In the adventitious root formation group, the number and length of adventitious roots were increased at lower concentrations of BL; however, they became trichome-like roots at higher levels of BL. The trichome-like root formation group showed better development when a low concentration of BL was added. However, at higher concentrations of BL, trichome-like root production was reduced, forming calli instead. In the calli formation group, more calli were formed at low BL concentrations and after persistent exposure to BL regardless of BL concentration, and the size of the leaf segments increased. The CNT103 gene, which is expressed at the root tips showed increased levels of expression at BL concentrations up to 10−9 M and decreased levels of expression at BL concentrations over 10−9 M in the adventitious roots, trichome-like roots, and calli formation groups.