Effect of aluminium on metabolism of starch and sugars in growing rice seedlings

Abstract

The effect of increasing concentrations of Al 2 (SO 4 ) 3 in situ on the content of starch, sugars and activity behaviour of enzymes related to their metabolism were studied in growing seedlings of two rice cvs. Malviya-36 and Pant-12 in sand cultures. Al 2 (SO 4 ) 3 levels of 80 and 160 lM in the growth medium caused an increase in the contents of starch, total sugars as well as reducing sugars in roots as well as shoots of the rice seedlings during a 5-20 days growth period. The activities of the enzymes of starch hydrolysis a-amylase, b-amylase and starch phosphorylase declined in Al-exposed seedlings, whereas the activities of sucrose hydrolyzing enzymes sucrose synthase and acid invertase increased in the seedlings due to Al 3+ treatment. The enzyme of sucrose synthesis, sucrose phosphate synthase showed decreased activity in Al 3+ treated seedlings compared to controls. Results suggest that Al 3+ toxicity in rice seedlings impairs the metabolism of starch and sugars and favours the accumulation of hexoses by enhancing the activities of sucrose hydrolyzing enzymes.

Copper Affects the Cotyledonary Carbohydrate Status During the Germination of Bean Seed

“…Moreover, the availability of sugars is regulated, at least, in part, by the carbohydrase activities [11,19,20,[26][27][28]. Glucose and fructose liberation from starch and sucrose is closely controlled by the activities of amylase and invertase which are the main suppliers of these hexoses during seed germination.…”

Unsuitable Availability of Nutrients in Germinating Bean Embryos Exposed to Copper Excess

“…2). Thus, copper excess appears to obstruct sugars and amino acids mobilization in the same way that in the germinating seeds of faba bean, pea, and rice exposed to Cd, Cu, and Al [11,13,14,29].…”

Effects of environmental factors on cereal starch biosynthesis and composition

“…Data on carbohydrate biosynthetic enzymes in cereals grown under toxic levels of Al 3þ are only available for rice vegetative tissues (Mishra and Dubey, 2008). Sugars and starch accumulate in shoots and to a lesser extent in roots, in response to high Al 3þ in a time-dependent manner (Mishra and Dubey, 2008).…”

“…Sugars and starch accumulate in shoots and to a lesser extent in roots, in response to high Al 3þ in a time-dependent manner (Mishra and Dubey, 2008). Diminished a-and b-amylase and increased SuSy activity respectively could conceivably increase starch levels, while the augmentation in acid invertase activity could promote higher sugars.…”

“…Diminished a-and b-amylase and increased SuSy activity respectively could conceivably increase starch levels, while the augmentation in acid invertase activity could promote higher sugars. The activities of PHO and SPS also decreased, but how or if they contribute to changes in carbohydrates is unknown (Mishra and Dubey, 2008). No other assays were performed, so the effect of Al 3þ on enzymes in the committed pathway of starch biosynthesis remains unanswered.…”