Propagating Bananas by Tissue Culture
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| Banana Plant |
Bananas are from the genus Musa and the Musaceae family. Edible bananas originated in the Indo-Malaysian area. Banana plants are perennial herbs, though they are commonly mistaken for trees. Today they are grown in humid tropical places and are the 4th largest fruit crop in the world.
The main method of propagating bananas is vegetatively with daughter suckers or pups. These contain portions of the roots, corm and rhizome from the mother plant. However, propagating bananas by way of tissue culture is preferred for commercial production and has many benefits. Since the explant used for tissue culture is carefully selected from a strong and high yielding mother plant, the plants will be disease free and high yielding. Banana plants grown from tissue culture also yield earlier than conventionally propagated plants. Tissue culture allows a large number of plants to be propagated in a short period of time, which is helpful for bananas since they are a highly demanded crop.
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| Working under a laminar flow hood
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Preparing the proper work area is essential. Your work area needs to be sterile and dust free to prevent contamination. If you can work under a laminar flow hood, then do so. However, if you do not have access to a hood then working in a box turned on its side will suffice. As long as you have some sort of cover to prevent dust from falling into work working area then you are good. All surfaces and instruments must be sterilized and cleaned prior to beginning the process.
Select your explant material from shoot tips from young suckers that are roughly 40-100cm in height. From that sucker, cut a piece that is roughly 1-2cm in length and that includes the apical meristem. The material needs to be sterilized first to prevent unwanted pathogens. First dip the explant into 70% ethanol for 10 seconds with tweezers so that the entire plant is emerged. Then place the plant material in a solution of 2% sodium hypochlorite for 20 minutes. Make sure to time this accurately because too little time won’t do the job and too much time with damage the plant material. The final sterilization step is to dip in sterile water 3 times.
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| Growing Medium *Note, this is not a banana plant* |
Using a sterilized sharp knife, cut the plant material into pieces between 5 and 10 mm in size. Carefully place the pieces directly onto the medium. Sterilize your knife frequently throughout this process.The medium most widely used, and which I recommend is Murashige and Skoog medium because it contain all the salts and nutrients needed for your plant. You can place as many pieces of explant on the medium as you please, just make sure its not crowded and that there is space for each explant to grow.
Once you are done, the petri dishes need to be taped closed, preferably using para-film and place in a growth chamber where you can control the temperature, light and humidity. Optimal temperature for banana tissue cultures are 27-30 degrees Celsius and optimal light cycle is 12-16 hours.
You should check for signs of pathogens and diseases daily. You should discard any plant materials that are showing signs of disease or infection immediately to prevent the contamination from spreading. Banana tissue cultures are susceptible to blackening that results from the oxidation of polyphenolic compounds that occur in the wounded tissues. This causes a barrier to form and prevents the plant tissues from taking up the nutrients essential to its survival. Because of this threat, the healthy explants should be transferred into new petri dishes every 1-2 weeks for the first 4-6 weeks. Ascorbic acid or citric acid in concentrations ranging from 10-150 mg/l can be added to the medium to reduce the chances of blackening. You can also dip the explant in cysteine 50 mg/l before you transfer it into the growing medium.
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| Successfully transplanted banana plant
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For rooting hormones, adding IBA and IAA at 2.25 mg/l and 0.175 mg/l respectively to the growing medium is highly recommended.
Once roots and shoots are established you need to start considering acclimating your banana plants. Start by taking the top off the petri dish for a period of a few days. A minimum period of 10 days is recommended before transplanting.
When transplanting, carefully remove the plants from the gel and wash all traces of the gel off. This is important because any gel material left on the plant could be a potential source for pathogens. Transplant the plants into plastic pots at least 6 inches in diameter with a potting mix that consists of 2 parts growing media mix, 1 part perlite and 3 parts vermiculite. This will give the plant roots the proper aeration and drainage that it needs. Make sure the soil is thoroughly and uniformly moistened prior to transplanting. The pots should be kept under a misting bench in a green house. The misting system should be closely monitored in the first few weeks after transplanting because the plants will be vulnerable and you don’t want to over water creating a favorable environment for pathogens or under water causing desiccation.
Sources
Banana Tissue Culture. S L V Plant Technologies Tvt. Ltd. http://slvplant.com/pdf/BANANA_TISSUE_CULTURE.pdf
Perez, E. and C. Hooks. Preparing Tissue-Cultured Banana Plantlets for Field Planting. Cooperative Extension Service. University of Hawaii at Manoa. https://scholarspace.manoa.hawaii.edu/bitstream/handle/10125/12175/BIO-8.pdf?sequence=1
Hartmann, H., Kester, D., Davies, F. and R. Geneve. 1999. Plant Propagation. Pearson Education, Inc. Upper Saddle River, NJ.
Morton, J. Banana. Fruits of Warm Climates. http://www.hort.purdue.edu/newcrop/morton/banana.html#Origin%20and%20Distribution
Strosse, H. Van Den H. and B. Panis. Cell and Tissue Culture, and Mutation Induction. Labratory of Tropical Crop Improvement. http://www.fao.org/docrep/007/ae216e/ae216e03.htm
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