Comparative investigations on the distribution of sucrose synthase activity and invertase activity within growing, mature and old leaves of some C₃ and C₄ plant species

Abstract

Claussen, W., Loveys, B. R. and Hawker, J. S. 1985. Comparative investigations on the distribution of sucrose synthase activity and invertase activity within growing, mature and old leaves of some Q, and C, plant species. -Physiol-Plant. 65; 275-280.Sucrose synthase (EC 2.4.1.13) activity in young growing leaves was highest in the leaf base in eggplants (Sotanum melongena L.), cassava (Manihoi esculenta Crantz), grapevine {Vitis vinifera L.), and in the leaf sheath of sugar cane (Saccharum offwinarum L.) and maize {Zea mays L.). In addition, increasing sucrose synthase activity was meastu-cd towards the edge of growing eggplant leaves while the activity in mature leaves was highest in the midrib. The activity of acid and alkaline invertase was very low in the midrib but higher in the blade of fully expanded eggplant leaves. Highest invertase activities were found in younger growing leaves. It was concluded that in growing leaves a close relationship might exist between the activity of sucrose synthase and the import of sucrose from source leaves. Detachment of mature eggplant leaves led to a 2-to 3-foId increase of sucrose synthase activity in blade and midrib of these leaves. In contrast, invertase activity decreased after detachment in both leaf blade and midrib,. It was concluded that the rise in sucrose synthase activity might have been caused by the observed increase of sucrose concentration in detached leaves and that sucrose synthase might have an important role in the regulation of sucrose content of the conducting tissue.

Determination of the Activity Signature of Key Carbohydrate Metabolism Enzymes in Phenolic-rich Grapevine Tissues

“…Past enzyme studies from grapevine leaf have instead used polyethylene glycol 4000 (PEG-4000) to bind phenolics. [21][22][23][24][25] When varying concentrations of PEG-4000 were added to extraction buffer, the highest invertase activity was observed with 3% (w/v) PEG-4000 (Table 1).…”

“…Four previously reported extraction buffers, including Jammer's extraction buffer B 11 and three buffers used in grapevine enzyme studies, 22,24,26 were tested in parallel for highest activities (see recipes in Table 2). Because activity of maize SuSy requires magnesium sulfate in extraction buffer, 24 buffers were tested with and without added Mg if it was not included in the published recipe.…”

“…Because activity of maize SuSy requires magnesium sulfate in extraction buffer, 24 buffers were tested with and without added Mg if it was not included in the published recipe. For ease of comparison, the protease inhibitors PMSF and benzamidine were added to all extraction buffers.…”

Sucrose Synthase and Invertase in Isolated Vascular Bundles

“…Although growing interest has centered on its involvement in sucrose metabolism by importing cells (2, 17), additional evidence also supports a possible vascular function (1,3,6). Recently, Yang and Russell (19) suggested that the promoter for one of the sucrose synthase genes in maize (shrunken 1 gene) was "phloem specific" in transgenic tobacco plants.…”

Identification of Actively Filling Sucrose Sinks

“…sucrolysis via either the invertases or by the sucrose synthase pathway. The reasons we developed this UDP and PPi-dependent assay for sucrose synthase activity were (a) to measure activity in the sucrose breakdown direction whereas many other workers measured the opposite, namely sucrose synthesis (3,4,22,26), and (b) others who measured sucrose breakdown often assayed for UDP-glucose accumulation as a precursor of the synthesis of cell walls or other nucleotide sugars (6,22). But in our assay we couple through the PPi-dependent UDP-glucopyrophosphorylase, which is very active in plants, to the formation of glucose 1-P which feeds carbon directly into glycolysis and possibly on to starch formation (31,32 …”