Metabolic Control of Sugarcane Internode Elongation and Sucrose Accumulation

Abstract

The relationship between metabolic changes occurring in the developing internodes of sugarcane and the final yield and sugar characteristics is poorly understood due to the lack of integration between phenotypic and metabolic data. To address this issue, a study was conducted where sugarcane metabolism was modeled based on the measurement of cellular components in the top internodes, at two stages of crop development. The study also looked at the effects of Trinexapac-ethyl (Moddus®) on growth inhibition. The metabolome was measured using GC-analysis, while LC-MS/MS was used to measure proteome changes in the developing internodes. These data were then integrated with the metabolic rates. Regardless of the growth rate, internode elongation was restricted to the top five internodes. In contrast, sucrose and lignin accumulation was sensitive to the growth rate. Crossover plots showed that sucrose accumulation only occurred once the cell wall synthesis had slowed down. These data suggest that sucrose accumulation controlled a reduction in sucrose breakdown for metabolic activity and a reduction in demand for carbon for cell wall polysaccharide synthesis. This study also found that nucleotide sugar metabolism appears to be a key regulator in regulating carbon flow during internode development.