Polyploidization in banana shoot apex and its morphophysiological effects in vitro

Abstract

The objective of this work was to evaluate the morphophysiological responses of shoot apex of diploid Musa acuminata subjected to in vitro polyploidization. The antimytotic agents colchicine (0, 1.25, 2.5, 3.75, and 5 mmol L^-1) and oryzaline (0, 15, 22.5, and 30  µmol L^-1), and two polyploidization periods were evaluated: 24 and 48 hours for colchicine, and 3 and 7 days for oryzaline. The application of colchicine significantly reduced the survival and the average number of shoots. Oryzaline had a slightly negative effect on shoot apex survival and positively influenced the average number of shoots per explant. High mortality and accentuated oxidation of treated and regenerated explants were observed with both antimytotics. However, the morphogenetic capacity of the explants was reestablished after successive sub-cultivations in fresh media, and the produced shoots were elongated/rooted and acclimatized successfully. Colchicine, at 1.25 and 3.75 mmol L^-1 concentrations, and oryzaline represent a viable and practical approach for banana breeding programs. The morphophysiological effects observed in vitro are important to define strategies for induction of polyploidy in banana plants.