Photoautotrophic micropropagation system (PAM): a novel approach deserving increased uptake for commercial plant production

Most commercial plant tissue culture laboratories still use conventional micropropagation systems, requiring air-tight vessels and gelled medium supplemented with sugar. There is, however, a more efficient and economic system available, called “photoautotrophic micropropagation system” (PAM). Application of sugar-free medium and ventilated vessels are the key features of this system, which significantly improves plant physiological processes including photosynthesis and transpiration. The genetic basis for this has become more clear with a recent transcriptomic analysis of potato plantlets cultured on sugar-free medium showing the upregulation of more than 2000 genes, many of which are associated with photosynthesis efficiency and leaf cell development. The cultured plants from PAM exhibit improved vigour and health enabling a faster and smoother acclimatisation stage. Moreover, PAM is amenable to automation and scaling up by using large culture vessels/rooms. Here, we reviewed the recent studies on PAM and the issues/barriers to its commercialisation have also been discussed. Optimal culture conditions as well as different types of culture vessels are also explained.