High-frequency protocorm-like bodies and shoot regeneration through a combination of thin cell layer and RITA® temporary immersion bioreactor in Cattleya forbesii Lindl.

Abstract

An efficient in vitro mass propagation through protocorm-like bodies (PLBs) was established in Cattleya forbesii Lindl., a commercially important orchid. Whole PLBs (W-PLB) and transverse thin cell layers of PLB (tTCL-PLB) explants were cultured in RITA® bioreactors based on temporary immersion system. Explants were transferred in semi-solid or RITA® bioreactor for protocorm production or shoot regeneration. The effect of different immersion frequencies, medium volumes and inoculum densities were studied and optimized. RITA® bioreactor cultures were found to be superior compared with semi-solid cultures regarding PLB production and shoot regeneration. tTCL-PLB explant types cultured in the RITA® bioreactor with immersion for 1 min/4 h, 250 mL of medium and 20 explants showed the highest number of PLBs per RITA® (2237 PLBs) and per explant (111.9 PLBs). The highest number of PLBs per explant was 21 times higher than those from semi-solid culture. The highest number of shoots per RITA® (3998 shoots) and per explant (199.9 shoots) were observed on tTCL-PLB cultured in RITA® bioreactor (1 min/4 h; 150 mL of medium and 20 explants). The highest number of shoots per explant was 95 times higher than those grown on semi-solid culture. Mass propagation of PLBs and shoots of C. forbesii Lindl. using combined thin cell layer and RITA® temporary immersion has been adapted in commercial practice.