SOMATIC EMBRYOGENESIS AND SHOOT PROLIFERATION OF MUSSAENDA CULTIVARS

Midrib sections of Mussaenda 'Queen Sirikit', 'Dona Luz', and 'Dona Hi laria' were cultured on Murashige and Skoog medium (MS) supplemented w ith 87.7 mM sucrose, 5 g agar l(-1), 0, 5, 10 or 20 mu M indole-3-acet ic acid (IAA) and 0, 0.5, 1, 2.5, 5, 10, 25 or 50 mu M 6-benzyladenine (BA). In addition, aseptic 5 mm shoot tips from 'Dona Luz' cultures w ere excised and cultured on MS basal salts, 0.6 mM myo-inositol, 1.2 m u M thiamine-HCl, 87.7 mM sucrose, 7 g agar l(-1), 0, 2.5, 5, 10, 20, or 40 mu M BA, 0 or 1 mu M alpha-naphthaleneacetic acid (NAA) and 0 or 217 mu M adenine sulfate at pH 5.8. Calluses began to develop after t wo weeks at the cut ends of midribs when cultured on a medium containi ng IAA. Somatic embryos first appeared at eight weeks but only on 'Que en Sirikit' callus. After 1 5 weeks the average number of somatic embr yos produced per tube decreased as the IAA concentration increased fro m 0 to 20 mu M. BA concentrations between 5.0 and 10.0 mu M resulted i n the largest number of somatic embryos per tube. After six weeks, the total, axillary and adventitious number of 'Dona Luz' shoots increase d as the BA concentration in the culture medium increased from 0 to 20 mu M Average shoot length and fresh weight decreased from 0 to 40 mu M BA. The addition of NAA to the culture medium reduced shoot number. Adenine sulfate in the presence of RA reduced the total number of shoo ts An ideal medium fnr proliferating the largest number of 'Dona Luz' shoots would be a MS medium supplemented with 10-20 mu M BA.