Abstract
Gentians are mainly cultivated as ornamental flowers in Japan. Because they are allogamous plants, their heterozygosity have become a major problem. Recently, explants were cultured clonally in vitro to maintain genetic purity, but the culture conditions had not been studied. We therefore investigated the effects of deficiency of potassium (K) and phosphorus (P), in the culture medium. The results showed that the explants could grow under K or P deficiency and P deficiency caused formation of new buds similar to overwintering buds. To elucidate the metabolic mechanism behind the gentian response to mineral deficiency, we performed targeted metabolome analysis using CE/MS. Multivariate analysis using metabolite profiles clearly revealed that characteristic metabolite patterns arise in response to K or P deficiency. Under P deficiency, a severe decrease in energy metabolites was observed, in contrast to K deficiency and the control conditions. Therefore, exogenous P controlled low energy metabolism of explants, which may in turn trigger new bud formation and sprouting in vitro. These findings will contribute to understand an appropriate cultural condition of gentians.
