Initially Stage II of this micropropagation method is recognised by the formation, growth and proliferation of adventitious shoots from the primary explant. Subsequently Stage II subcultures might, theoretically, be established from individual shoots by the techniques familiar in shoot culture. In practice, in plants such as Saintpaulia, both further adventitious and axillary shoots may develop in later stages of propagation. The result is a highly proliferative shoot mass and a very rapid rate of propagation. Subcultures are made by transferring shoot clumps (avoiding basal callus) to fresh media. In most commercial laboratories the micropropagation of Anthurium species is initiated by adventitious shoot formation on leaf explants, followed by only axillary shoot development during the succeeding subcultures (Debergh et al,, 1990). Adventitious shoots sometimes arise directly from the leaves of plants during shoot culture. This often happens when leaves bend down to touch the semisolid medium. Adventitious shoot formation of certain plants will take place in large vessels of aerated liquid medium, allowing the scale of propagation to be much increased (see the discussion on liquid media in Chapter 12).
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