Determination of the optimum initial callus weight for the efficient propagation of sugarcane in temporary immersion bioreactor

Abstract

Temporary immersion bioreactor (TIB) has been utilized for the mass-scale propagation of many important plants, including sugarcane. TIB facilitates a semiautomated culture system and provides optimal conditions for plant growth. Several factors determine plant growth in the TIB, such as explant density. Therefore, an experiment was carried out to determine the optimal initial weight of sugarcane calli and to evaluate its effect on the proliferation and regeneration in TIB. Sugarcane calli were induced from spindle leaves isolated from four Indonesian prime sugarcane varieties. The initial weights of the calli cultured in the TIB flasks were 0.05 g, 0.1 g, 0.2 g, 0.5 g and 1.0 g per flask. The calli were proliferated through three cycles in TIB, and subsequently regenerated in TIB with auxin and cytokinin treatments. The results of the experiments showed that 0.2 g was the most efficient initial weight for sugarcane callus proliferation in the TIB, resulting in an exponential multiplication rate of 130.3-fold (PSKA 942), 136.8-fold (PS 094), 21.3-fold (PS 881), and 12.9-fold (PS 091) within 12 weeks. In the TIB, callus density showed a negative correlation with the physicochemical properties of the medium, demonstrating various growth intensities or metabolic activities of calli at different densities in the TIB. The use of 0.2 mg L-1 BAP along with 0.2 mg L-1 kinetin was suitable for promoting the regeneration of sugarcane calli and producing the highest number of shoots in a relatively short amount of time (1 – 2 weeks faster) with low incidences of browning.

Keywords

• in vitro culture
• liquid culture
• proliferation