Methylglyoxal-induced enhancement of somatic embryogenesis and associated metabolic changes in sugarcane (Saccharum spp. hybrids)

The production of regenerable embryogenic callus is essential to sugarcane genetic improvement. However, some sugarcane cultivars display poor calli yields using established in vitro protocols. In this study, we tested the impact of methylglyoxal (MG) on embryogenic callus and plantlet development in cultivars NCo376 and N41. Calli were exposed to 0-10mM MG at embryo maturation and germination stages. For both cultivars, the 2 and 4mM MG treatments increased callus dry mass by up to 48%, but 70-80% decreases were observed when calli were exposed to 7 and 10mM. The 2 and 4mM MG treatments also produced more compact white embryogenic callus than the control. Incorporation of MG at the same levels during embryo germination promoted faster shoot morphogenesis in both cultivars and increase plantlet yield in NCo376 by 130% when treated with 4mM MG. In both cultivars, MG levels higher than 7mM had a negative or no effect plantlet production. Metabolic profiling revealed higher levels of sugars in MG-treated than in control calli, which may have contributed to development of more white compact calli. Separate clustering of NCo376 and N41 MG-treated calli in principal component and hierarchical clustering analyses of the metabolic profiles, suggested variations in MG metabolism among the genotypes that may account for variations in the MG-induced effect on somatic embryogenesis between the two cultivars. Although the effect may be genotype-dependant, low MG concentrations can induce improved embryogenic callus and plantlet development in sugarcane.