Micropropagation of Cariniana legalis (Martius) O. Kuntze, an endangered hardwood tree from the Brazilian Atlantic Forest

Abstract

The aim of this study was to establish the best conditions for in vitro germination, organogenesis and rooting of micropropagated shoots of Cariniana legalis. For in vitro germination, the effects of Murashige and Skoog (MS) and woody plant medium (WPM) were tested. The effect of different combinations and concentrations of N6-benzyladenine, α-naphthaleneacetic acid, gibberellic acid and polyamines on direct organogenesis were investigated. The indole-3-butyric acid (IBA) was tested for the ex vitro rooting of shoots. The WPM culture medium resulted in higher in vitro seed germination (66%) and seedling growth compared to MS culture medium (25%). The development of shoots was achieved in WPM culture medium without addition of plant growth regulators (control treatment). The explants from cotyledonary nodal segments provided a greater number and length of shoots compared to apical nodal in the control treatment. Ex vitro rooting of micropropagated shoots was achieved in the absence of IBA. A higher root induction was obtained in shoots arising from cotyledonary nodal explants (75%) compared to those from apical nodal explants (50.3%). This work is one of the first describing the establishment of micropropagation in C. legalis, an important wood species, and the results are relevant for establishing further plant conservation strategies for threatened tree species