Amending Storage Vessel and Media Improves Subculture Interval of Musa sp. Tissue Culture Plantlets

Bananas and plantains (Musa sp.) are some of the most important food crops in the world.  The USDA-ARS, Tropical Agriculture Research Station Musa spp. collection consists of 140 accessions maintained as clonally propagated plants in field plots as well as in tissue culture.  Accessions maintained in tissue culture require routine sub-culturing as the nutrient medium is lost due to uptake by the plant.  Current subculture intervals are carried out, every six months which is a resource- and time-consuming effort.  In an attempt to lengthen the subculture interval period, an experiment was conducted to evaluate modified nutrient medium recipes as well as different storage vessels on four Musa spp. accessions. Three containers were tested: 1) glass test tubes, 2) glass test tubes + Parafilm® and, 3) in tissue culture bags.  In addition, three medium formulations: 1) standard MS, 2) half-strength MS and, 3) MS with 4% mannitol were also evaluated.  Treatment effects were determined by measuring root and leaf growth, number of suckers and rating plant vigor.  Glass test tubes + Parafilm® and culture bags resulted in increased transfer intervals regardless of variety and medium formulation.  Accessions did not have a significant effect on subculture interval.  Subculture interval for glass test tubes + Parafilm® and tissue culture bags was extended an additional 6 months.  Although at the experiment’s termination the healthiest plants could be found in the half strength standard MS medium combined with the glass tubes + Parafilm®, additional advantages with the culture storage bags were identified, mainly the ease of using them for distribution purposes.  The USDA-ARS TARS is the official Musa spp. germplasm repository for the National Plant Germplasm System and as such distributes these genetic resources for research and education purposes.