Protocols for Micropropagation of Woody Trees and Fruits

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2.5. Micropropagation
S.J. MURCH ET AL.
Mass production of rooted breadfruit plants can be achieved by placing differentiated
shoots from aseptic stock cultures in solid or liquid culture systems. The solid
and liquid systems can also be utilized in combination to maximize the plantlet proliferation
and growth rates.
2.5.1. Solid Culture System for Rooted Plant Production
1. Excise 2 cm-long shoot explants with 2 nodes from the aseptic stocks and
remove the leaves of the lower node.
2. Place up to five shoot explants in Magenta boxes containing 65 ml of solid
Artocarpus rooting (SAR) medium supplemented with 1 µM IAA (0.175
–1
mg l ). Ensure that the shoot explants are in contact with the culture medium by
pushing the bottom portions (0.5–1.0 cm) of the buds gently into the medium.
Place the cultures in the same growth room as stock cultures.
3. Examine the cultures for rooting response after 2 weeks. Normally, the
roots differentiate within 2 weeks of culture from nodal section in contact
with the medium.
4. Whole plantlets with about 6 cm long shoots and well established root systems
develop after 6 weeks of culture. Nearly 100% of the shoot cultures
form plantlets suited for potting and transfer to a growth chamber (Figure 1D).
2.5.2. Liquid Culture System for Plant Production
1. Excise 0.5–1 cm long shoot explants with a single intact node.
2. Place 15 explants in a Liquid Lab vessel with 100 ml of liquid Artocarpus
rooting (LAR) medium with 5 µM IAA (0.875 mg l –1 ).
3. The vessels are placed on the Liquid Lab Rocker system (Southern Sun
Biosystems Inc., Hodges, SC, USA) to provide a gentle side to side rotation
with a 30 s cycle at 1.2 min interval between cycles. Growth conditions in
the culture room are set to provide a 16 h photoperiod with an intensity of
–2 –1
25–40 µmol m s
at a temperature of 20–24°C.
4. Replace the culture medium after 13 weeks with 100 ml of liquid MSO and
every 4 weeks thereafter.
5. After 6 months of culture, all explants turn to clumps of shoots with well
developed roots (Figure 1E). Separate the rooted shoots from clumps and
transfer them to a growth chamber for further development.
2.6. Transfer of Rooted Plants to Greenhouse
1. Plantlets with well-formed roots obtained from both solid and liquid culture
systems are suitable for transplantation. In vitro-rooted plants are acclimatized
before transfer to greenhouse.
2. Wash the plants with tap water to eliminate nutrient media and transplant in
4-inch plastic pots containing a soil-less mix (Promix BX, Premier Horticulture
Ltd, Quebec, Canada).