In vitro propagation of Rauvolfia serpentina through tissue culture.

Multiple shoots were induced from nodal segments and shoot apices of Rauvolfia serpentina and MS medium containing 1.0 mg/l BA and 0.1 mg/l NAA was found to give the best shoot proliferation rate. Callus formed at cut bases of the explants which produced shoots when subcultured on media containing low concentration of BA (0.5 or 0.1 mg/l) and NAA (0.1 mg/l). The in vitro proliferated shoots were rooted and later transferred to the soil.

Production of plantlets from Aegle marmelos nucellar callus.

Techniques have been developed for the regeneration of Aegle marmelos from nucellar explants. Slow-growing calli were induced from nucellar explants excised from 90-120 d-old developing fruits. The medium consisted of Murashige and Skoog formulation containing 40 g/l sucrose, 400 mg/l casein hydrolysate, 5 mg/l 1-naphthaleneacetic acid and 1 mg/l kinetin. The basal medium with high concentration (1-5 mg/l) of N6-benzyladenine (BA) and low concentration (0.1 mg/l) of NAA was suitable for regeneration of shoots from 3-month-old calli. Addition of 1 mg/l gibberellic acid (GA3) favoured shoot growth. Callus-derived shoots produced roots and developed into plantlets when transferred to half-strength MS medium supplemented with 0.5 mg/l indole-3-butyric acid (IBA) and 0.5 mg/l NAA. Approximately 5 months were required for the full regenerative process.

High efficiency plant regeneration from petiole explants of Carica papaya L. through organogenesis.

Callus cultures were obrained from petiole explants of Carica papaya on MS medium containing 0.5-10.5 µM α-naphthaleneacetic acid (NAA) in combination with 0.5-5 µM benzyladenine (BA). Hard-green calli were transferred to MS medium containing 100 mgl(-1) casein hydrolysate (CH) with specific BA-NAA formulation, where they developed adventitious buds within 2 weeks of culture. Maximum number of adventitious buds were obtained in 2 µM BA and 0.1 µM NAA. Shoot regeneration occurred from these adventitious buds by the end of the 4th week. Regenerated shoots were elongated in hormone-free medium and rooted in half-strength MS fortified with 3 UM NAA and 0.5 µM gibberellic acid (GA3). The regenerants were transferred to soil after acclimatization.

Micropropagation of Morus laevigata Wall. from mature trees.

Multiple shoots were obtained from nodal explants of 10-year-old tree of Morus laevigata on Murashige and Skoog's medium supplemented with different concentrations (0.5-5.0 mg.l(-1)) of benzyladenine (BA). Nodal segments taken from in vitro proliferated shoots gave further multiple shoots when cultured on the same basal medium containing 2.5 mg.l(-1) BA. Repeated subculture resulted in rapid shoot multiplication at the average rate of 6-fold per subculture. In vitro raised shoots rooted on MS medium containing 0.1 mg. l(-1) each of 3-indolebutyric acid (ISA) and α-naphthaleneacetic acid (NAA). The regenerated plantlets were successfully established in soil under field conditions after a few days of indoor acclimatization.

In vitro response of leaf tissues from Lolium multiflorum - a comparison with leaf segment position, leaf age and in vivo mitotic activity.

Immature gramineous leaves provide a convenient system for comparing the response of cells in culture with their state of differentiation. Callusing frequency is compared with leaf segment position, leaf age and in vivo mitotic activity in Lolium multiflorum. (1) In a succession of one millimeter sections from the immature leaf base, callus was formed from the first and second sections but not the third or subsequent sections. The frequency of those explants callusing decreased with distance from the base of the leaf and with leaf age (or leaf extension growth). (2) In vivo, the proportion of cells in mitosis declined from around 10-14% at the base of young leaves to zero at 5 mm from the base and beyond. Mitotic activity also declined in leaves as they aged, and dividing cells were not observed in leaves 30 days from initiation or older. (3) A high frequency of callus formation was associated with a high mitotic index in the explant. But for corresponding mitotic indices, cells further away from the leaf base were less responsive in culture. (4) It is proposed that cells are becoming differentiated even in highly meristematically active regions of the leaf and concomitantly losing their ability to respond in culture.