Field evaluation of plants produced in vitro initiated from a phenotypically distinct, apparently healthy dwarf 'French-type' plantain clone 'Dwarf Superplatano' (Musa 'AAB') was carried out at three sites in Puerto Rico. The use of the floral axis tip from a 'mother plant' versus vegetative apices from lateral buds of the same plant as a source of the primary explant was compared and contrasted. Material from floral axis tip consistently showed high phenotypic uniformly whereas materials from vegetative apices of 'sword' suckers were less so. 'Virus-like symptoms' that became apparent in much of the material just before flowering (shooting stage) were determined to be due to the badnavirus banana streak virus (BSV), a dsDNA pararetrovirus. The 'good news' is that a primary explant taken from the floral axis tip was quicker in its initial response to yield a multiplication system in vitro, and produced significantly fewer virus-infected plants, ca. 5%. By contrast, primary explants obtained from the vegetative sucker-derived apices were later in their production of initial buds, and produced many more virus-infected plants, an average of 32%. Comparison of vegetative-apex-derived plants and floral axis tip-derived plants disclosed no evidence that apices from vegetative suckers or floral stem tips gave rise to genetic off-types due to mutations were brought about by the in vitro process per se. Phenotypic differences were due to virus infestation. The 'bad news' is that this dwarf plantain clone of considerable interest and potential in Puerto Rico can show very severe BSV symptoms. The occurrence of BSV infection in tissue culture-derived plants may be related to the presence of viral sequences integrated into the host genome, in which case there is no apparent strategy to rid the clone of this 'virus'.
Bibliographical noteFunding Information:
This paper covers work carried out cooperatively between the Agricultural Research Service-USDA and the Agricultural Experiment Station, University of Puerto Rico (AES-UPR), Rio Piedras, Puerto Rico and Professor A.D. Krikorian. Earlier parts of the tissue culture work were supported by a grant to A.D. Krikorian from the US Agency for International Development for a project entitled “Tissue Culture for Banana and Plantain Improvement”. Research on occurrence and identification of BSV in Musa was supported by a grant to B.E.L Lockhart from the International Network for the Improvement of Banana and Plantain.
- Banana streak virus (BSV)
- Clonal multiplication
- Somaclonal variation
- Tissue culture