The reduction of starch accumulation in transgenic sugarcane cell suspension culture lines

Abstract

Starch only occurs in small amounts in sugarcane, but is, nevertheless an unwanted product because it reduces the amount of sucrose that can be crystallized from molasses. In an attempt to reduce the starch content of sugarcane, the activities of ADP-glucose pyrophosphorylase (AGPase) and beta-amylase were manipulated using transgenic approaches. Transformation vectors to reduce AGPase activity and to increase plastidial beta-amylase activity were constructed and used for the transformation of sugarcane calli. The results of the manipulations were analyzed in suspension cultures. AGPase activity was reduced down to between 14 and 54% of the wild-type control. This led to a reduction in starch concentration down to 38% of the levels of the wild-type control. beta-Amylase activity was increased in the transgenic lines by 1.5-2 times that of the wild-type control. This increase in activity led to a reduction in starch amounts by 90% compared to wild-type control cells. In both experiments, the changes in starch concentrations could be correlated with the change in enzyme activity. There were no significant effects on sucrose concentrations in either experiment, indicating that these approaches might be useful to engineer regenerated sugarcane for optimized sucrose production.

Luxurious Nitrogen Fertilization of Two Sugar Cane Genotypes Contrasting for Lignin Composition Causes Changes in the Stem Proteome Related to Carbon, Nitrogen, and Oxidant Metabolism but Does Not Alter Lignin Content

“…When overexpressed in transgenic sugar cane cell culture this enzyme led to reduced starch concentration. 92 Along with that, ferredoxinnitrite reductase was increased in the same genotype (Table S7). This enzyme is critical for N assimilation in the reduction of nitrite to ammonia.…”

Metabolic engineering of sugars and simple sugar derivatives in plants

“…In crops like sugarcane, selection for high sucrose levels has resulted in very low levels of starch (Ferreira et al, 2008). It is hard to imagine further large gains in sucrose content at the expense of proteins, lipids and other metabolites that comprise a small fraction of harvested dry weight and are essential for plant cell structure and function (Bindon and Botha, 2002).…”

Seasonal Carbohydrate Dynamics and Climatic Regulation of Senescence in the Perennial Grass, Miscanthus

“…In soluble sugar-accumulating plants such as sugarcane, starch is also present in the green tissues but in very low quantities of <0.5 mg g −1 FW, whereas switchgrass stores a greater abundance of starch in its stems than soluble sugars [14][15][16]. Miscanthus is more closely related to sugarcane than switchgrass and correspondingly Miscanthus × giganteus accumulates a greater concentration of sugars, rather than starch in its stems [6,17,18].…”