Poliploidização em ápices caulinares de bananeira e seus efeitos morfofisiológicos in vitro ; Polyploidization in banana shoot apex and its morphophysiological effects in vitro

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. ; O objetivo deste trabalho foi avaliar as respostas morfofisiológicas de ápices caulinares de diploides de Musa acuminata submetidos à poliploidização in vitro. Foram avaliados os antimitóticos colchicina (0, 1,25, 2,5, 3,75 e 5 mmol L-1) e orizalina (0, 15, 22,5 e 30 µmol L-1), e dois tempos de poliploidização: 24 e 48 horas para colchicina, e 3 e 7 dias para orizalina. A aplicação de colchicina reduziu significativamente a sobrevivência e o número médio de brotos dos ápices. A orizalina teve um leve efeito negativo na sobrevivência dos ápices caulinares e influenciou positivamente o número médio de brotos por explante. Observou-se alta mortalidade e níveis acentuados de oxidação dos explantes primários tratados e regenerados, com ambos os antimitóticos. No entanto, a capacidade morfogenética dos explantes foi restabelecida após ...