Optimizing culture medium for meristem tissue culture of several Saccharum species and commercial hybrids

Authors: Cheong, Eun; Mock, Raymond; Li, Ruhui

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2010
Publication Date: 12/11/2009
Citation: Cheong, E.J., Mock, R.G., Li, R. 2009. Optimizing culture medium for meristem tissue culture of several Saccharum species and commercial hybrids. American Society of Sugar Cane Technologists. 29:149-165.

Interpretive Summary: Modern sugarcane cultivars are complex hybrids within the genus Saccharum. To improve agricultural traits in commercial cultivars, breeding programs import different cultivars or wild related species from foreign countries through the federal plant quarantine programs. Some of these foreign materials are infected with plant pathogens including many viruses that may damage domestic sugarcane production. The pathogens need to be eliminated by a technique called in vitro meristem tissue culture to produce healthy sugarcane. The technique involves growing tiny shoot tips (0.5-1.0 mm) that may be free of viral invasion on an artificial solid medium to regenerate the plants. One challenge faced in the federal quarantine programs is that currently used medium for culturing sugarcane shoot tips is not suitable for growth of many species. In this study, the optimum concentrations of three major nutrients (nitrogen, phosphorus and potassium) and several plant growth regulators are reported for the in vitro cultivation of four hybrid cultivars and six wild species of Saccharum. This protocol will be used by the federal quarantine programs as well as other certification and research programs.

Technical Abstract: The optimal range of medium nutrients and plant growth regulators (PGR) was investigated for in vitro culture of diverse sugarcane species and cultivars. Macro-nutrients, nitrogen (N), phosphorous (P) and potassium (K), were essential for growth of leaf primordia. Although the best concentration of N, P and K differed among species and cultivars, 41-66 mM of N, 0.6-1.25 mM of P and 10-30 mM of K were the optimal ranges for all tested sugarcane. An excess of N and P (1.5-2 fold of commonly used media) had an inhibitory effect on meristem growth. No obvious inhibitory effects of low (10 mM, half of normal media) or high (30 mM, 1.5 fold of normal media) concentrations of K were found. Cytokinins (BA and kinetin), GA3 and auxin (NAA), were all critical for maintaining viability and growth of meristems. By adding PGR to the initiation medium, outgrowth and further shoot elongation were significantly increased. On average, over 60% of the shoots elongated on a medium containing 0.25 µM BA, kinetin, 0.1 µM GA3 and 0.1 µM NAA. Cytokinins (0.5-1.0 µM) combined with low level of GA3 and NAA were adequate for all species and cultivars.