Abstract:

1-Aminocyclopropane-1-carboxylic acid synthase (ACS) is one of the key rate-limiting enzymes for ethylene biosynthesis in higher plant. In order to study expressions of ACS genes in stalks regulated with ethephon and its correlation with ethylene production and sucrose accumulation in sugarcane, the spatial and temporal expressions of the three genes were tested in the stalks of sugarcane with Sc-ACS1, Sc-ACS2, and Sc-ACS3 as the probes, respectively, based on the cloning of Sc-ACS1, Sc-ACS2 and Sc-ACS3 of ACS gene family. Northern blotting analysis showed that three members of ACS gene family kept expressions during late growth stage in the varieties and internodes with a lower level except of Sc-ACS3. Ethephon treatment increased expressions of the three genes in the immature and maturing internodes. Sc-ACS1 and Sc-ACS2 maintained the highest expression level for 30 d and returned to normal level later, however, Sc-ACS3 kept the highest level for 45 d in the immature stalks. The ethephon-induced gene expressions were in accordance with the significant effects on ethylene production and sucrose accumulation in the immature and maturing internodes. The ethylene production was correlated negatively with the sucrose accumulation in internodes of variety GT17 significantly at P≤0.01 and P≤0.05 at 14 d and 28 d after treatment with ethephon, respectively, but not significantly in the variety B1.

Key words: Saccharum officinarum L., 1-Aminocyclopropane-1-carboxylic acid synthase, Expression, Ethylene production, Sucrose accumulation