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<p>The banana plant is a crop of great economic importance, widely cultivated in tropical and subtropical regions around the world. One of the main limiting factors in banana production is the fungus <i>Fusarium oxysporum</i> f. sp. <i>cubense</i> (Foc), the causal agent of Fusarium wilt. Cavendish bananas are susceptible to both Tropical Race 4 (TR4) and Subtropical Race 4 (SR4) of the pathogen. Although TR4 has not yet been identified in banana-producing areas of Brazil, the races already present require the development of resistant cultivars. Cavendish bananas have a high level of female sterility, which makes conventional breeding very difficult. One promising strategy for develop new Cavendish cultivars is the induction of mutations through tissue culture techniques. Given this scenario, the present study aimed to induce mutations using gamma radiation from a cobalt-60 source, applied to the shoot apices of the Valery and Grande Naine cultivars (genome AAA). Two radiation doses were tested: 20 Gy and 30 Gy. A total of 1,051 mutant plants were phenotypically evaluated for internal symptoms in greenhouse conditions. Of these, 57 resistant mutants with a score of 0 indicating no symptoms after 150 days of exposure to the pathogen were selected. Histochemical and histological analyses performed on the resistant mutants indicated possible defense mechanisms against Foc, including increased production of phenolic compounds and the presence of cellulose and callose in the roots. In some mutants, no pathogenic structures (such as hyphae and chlamydospores) were observed, suggesting resistance to pathogen penetration. It is concluded that gamma irradiation is effective in inducing mutations in Cavendish cultivars, with the 20 Gy dose being the most effective among those tested. Promising mutants of the Valery and Grande Naine cultivars, designated MV8, MV23, MV39, MG7, and MG8, showed no pathogenic structures and exhibited all three defense mechanisms analyzed in this study. These results suggest the activation of post-formed resistance mechanisms capable of preventing the spread of pathogen infection. Further agronomic and molecular characterization studies will be conducted on the resistant mutants identified, aiming to deepen understanding of their traits and productive potential.</p>

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Gamma radiation-induced mutagenesis in the development of Cavendish subgroup banana cultivars resistant to Fusarium oxysporum f. sp. cubense

  • 期刊论文

  • 发表日期：

    2025年8月24日

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  • Taís Ferreira Costa,
  • Manoela Caldas Santos,
  • Luiz Carlos de Souza Junior,
  • Danilo Almeida Brito,
  • Anelita de Jesus Rocha,
  • Lucymeire Souza Morais Lino,
  • Glaucia Amorim Faria,
  • Claudia Fortes Ferreira,
  • Fernando Haddad,
  • Edson Perito Amorim,
  • Janay Almeida dos Santos-Serejo

摘要

The banana plant is a crop of great economic importance, widely cultivated in tropical and subtropical regions around the world. One of the main limiting factors in banana production is the fungus Fusarium oxysporum f. sp. cubense (Foc), the causal agent of Fusarium wilt. Cavendish bananas are susceptible to both Tropical Race 4 (TR4) and Subtropical Race 4 (SR4) of the pathogen. Although TR4 has not yet been identified in banana-producing areas of Brazil, the races already present require the development of resistant cultivars. Cavendish bananas have a high level of female sterility, which makes conventional breeding very difficult. One promising strategy for develop new Cavendish cultivars is the induction of mutations through tissue culture techniques. Given this scenario, the present study aimed to induce mutations using gamma radiation from a cobalt-60 source, applied to the shoot apices of the Valery and Grande Naine cultivars (genome AAA). Two radiation doses were tested: 20 Gy and 30 Gy. A total of 1,051 mutant plants were phenotypically evaluated for internal symptoms in greenhouse conditions. Of these, 57 resistant mutants with a score of 0 indicating no symptoms after 150 days of exposure to the pathogen were selected. Histochemical and histological analyses performed on the resistant mutants indicated possible defense mechanisms against Foc, including increased production of phenolic compounds and the presence of cellulose and callose in the roots. In some mutants, no pathogenic structures (such as hyphae and chlamydospores) were observed, suggesting resistance to pathogen penetration. It is concluded that gamma irradiation is effective in inducing mutations in Cavendish cultivars, with the 20 Gy dose being the most effective among those tested. Promising mutants of the Valery and Grande Naine cultivars, designated MV8, MV23, MV39, MG7, and MG8, showed no pathogenic structures and exhibited all three defense mechanisms analyzed in this study. These results suggest the activation of post-formed resistance mechanisms capable of preventing the spread of pathogen infection. Further agronomic and molecular characterization studies will be conducted on the resistant mutants identified, aiming to deepen understanding of their traits and productive potential.