Banca de DEFESA: ALANA JENNIFER ALVES DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ALANA JENNIFER ALVES DOS SANTOS
DATA : 26/03/2026
HORA: 08:00
LOCAL: CIP Cerrado - Sala da Pós Graduação
TÍTULO:

Induction of Polyploidy in Triploid Banana BRS Terra-Anã: Protocol Optimization, Cytogenetic Characterization, and Implications for Genetic Improvement

PALAVRAS-CHAVES:

colchicine, mixoploids, hexaploids, polyploidy, flow cytometry, reconstructive breeding

PÁGINAS: 62
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Fitotecnia
ESPECIALIDADE: Melhoramento Vegetal
RESUMO:

The cultivar BRS Terra-Anã is a triploid hybrid (3n = 3x = 33) belonging to the AAB genomic group, developed by the genetic breeding program of Embrapa Cassava and Fruits. Due to its gametic sterility, its multiplication occurs exclusively through an agamic pathway, with in vitro micropropagation being the main strategy for producing plantlets with high genetic fidelity and phytosanitary quality. In this context, the present study aimed to induce duplication of the triploid genome of the cultivar BRS Terra-Anã through in vitro culture, evaluating different colchicine concentrations and their effects on survival, regeneration, ploidy level, and morpho-agronomic characteristics of regenerated plants. Shoot survival was influenced by both colchicine concentration and exposure time. The control treatment showed 100% survival, while treatments with 0.1% colchicine maintained high values, reaching 98.4% at 24 hours and 93.3% at 36 hours. At 0.2%, survival also remained high, with 98.3% (24 h) and 96.7% (36 h). At higher concentrations, a progressive reduction in survival was observed, with values of 95.0% (0.3%/24 h) and 86.7% (0.3%/36 h), reaching 85.0% (0.5%/24 h) and 78.3% (0.5%/36 h). Regarding regeneration, the highest average number of shoots per explant was recorded at 0.1% for 36 hours (2.1 shoots/explant) and in treatments of 0.2% and 0.3% for 24 hours (1.9 to 2.0 shoots/explant). On the other hand, the concentration of 0.5%, especially for 36 hours, resulted in a marked reduction in regeneration, with an average of 1.2 shoots per explant. The ploidy level of regenerated plants was confirmed by flow cytometry, cytogenetics, and stomatal characterization. Hexaploid plants showed nuclear DNA content around 6C = 9.00 pg and chromosome number 3n = 6x = 66. The highest polyploidization efficiency was observed in the treatment with 0.2% colchicine for 36 hours, in which 23.7% hexaploid plants were obtained, maintaining a high survival rate (96.7%). At higher concentrations (0.3–0.5%), the frequency of mixoploids ranged from 10.5 to 24.0%, but was associated with reduced survival and low hexaploid formation. Stomatal characterization showed an increase in stomatal length, width, and area with increasing ploidy level, accompanied by a reduction in stomatal density on both leaf surfaces. Evaluation of morpho-agronomic characteristics indicated that hexaploid cytotypes showed greater height, longer and wider leaves, greater pseudostem thickness, and a more developed root system when compared to triploids and mixoploids, reflecting the gigas effect associated with polyploidization. This work represents a significant contribution to knowledge about triploid→hexaploid conversion in banana, a poorly documented process in the literature, and provides optimized protocols for application in reconstructive breeding programs.

MEMBROS DA BANCA:
Presidente - 59687004 - MAURECILNE LEMES DA SILVA CARVALHO
Externo ao Programa - 131840001 - ILIO FEALHO DE CARVALHO
Externo à Instituição - 004.473.225-24 - ELYABE MONTEIRO DE MATOS - UFJF
Externo à Instituição - OTALÍCIO DAMÁSIO DA COSTA JUNIOR - UFV