Changes in Activities of Key Enzymes in Sugarcane Stem at Different Growing Stages

Sugarcane is the most important sugar crop in China, which mainly focuses on the upper stem of the harvested land. The proper regulation of the proportion of internode elongation is the key to determine the yield and sugar. Therefore, it is of great significance to study the mechanism of the dynamic change of elongation between cane joints in order to improve the yield of sugar cane and sucrose. To investigate the biochemical mechanism of stem elongation in sugarcane, stem samples were collected at the pre-elongation stage (9-10 leaves) (Ls1), early elongation stage (12-13 leaves) (Ls2) and rapid elongation stage (15-16 leaves) (Ls3). The change trends in the activities of NAD kinase (NADK), calcium-dependent protein kinase (CDPKs), α-mannosidase, α-galactosidase, β-glucosidase, cellulase, xyloglucan endo-transglycosylase/hydrolase (XTH) and catalase (CAT) were completely consistent, showing rapid elongation stage > early elongation stage > pre-elongation stage, while the activities of β-glucosidase, peroxidase (POD) and α-glucosidase were in opposite, and the activities of calmodulin and β-mannosidase showed the same single-peak trend, and the peak was at early elongation stage. The enzyme activities of β-galactosidase and pectinase did not show significant difference at different stages. The results indicate that the elongation of internodes was closely related to the complex physiological metabolism of sugarcane, and the key enzymes play roles at different time but β-galactosidase and pectinase have little effect on internodes elongation in sugarcane.