Circadian and developmental regulation of vacuolar invertase expression in petioles of sugar beet plants

Abstract

The expression pattern of the genes coding for vacuolar and extracellular invertase activity was analyzed in sugar beet (Beta vulgaris) and compared with the expression of sucrose synthase in this important sucrose-storing crop. Northern blot analysis revealed that sucrose synthase is the predominant sucrose-cleaving enzyme in tap roots, whereas vacuolar invertase was specifically expressed in petioles. Extracellular invertase transcripts showed low abundance in all the sugar beet organs and were not detected in northern blots. Relative RT-PCR analysis revealed differential expression of the two extracellular invertase genes: BVInv-CW1 was almost exclusively expressed in tap roots and BVInv-CW2 was widely expressed in all the organs analyzed. A remarkable result of this analysis was the high expression of vacuolar invertase (BVInv-V3) in petioles. Two factors had a clear influence on vacuolar invertase gene expression in petioles: light and the developmental stage, so that expression was higher in petioles from juvenile plants. BVInv-V3 transcripts showed circadian oscillation in petioles, with maximal accumulation during the light period. A similar pattern of diurnal oscillation was also observed for the vacuolar invertase activity, showing a delay with respect to the level of transcripts. The analysis of sugars in petioles revealed oscillation of the hexoses, with a remarkably higher content of glucose than fructose. In contrast, the level of sucrose in petioles was very low. This pattern of expression suggests an important role of petiole vacuolar invertase in plant development and photoassimilate partitioning.

The effect of high electric field pulses on activity of sugar beet o-diphenol oxidase and yeast invertase

“…The supernatant did not display a-glucosidase activity (assayed for p-nitrophenyla-D-glucopyranoside). Our results are consistent with that of Klotz and Finger (2004) and Gonzalez et al (2005), who also reported that the activity of sugar beet root invertases was very low. This benefits sucrose manufacture because its losses are reduced during extraction.…”

Mathematical Modeling of the Central Carbohydrate Metabolism in Arabidopsis Reveals a Substantial Regulatory Influence of Vacuolar Invertase on Whole Plant Carbon Metabolism

“…Considering that Calvin cycle intermediates are part of this pool, this would explain the delayed start of photosynthesis in the inv4 mutant and indicates a role of Suc cycling and, hence, of leaf invertase in controlling sugar phosphate pools. While functions of invertase have clearly been demonstrated for growthrelated processes in juvenile petioles of sugar beet (Beta vulgaris; Gonzalez et al, 2005) or tobacco (Nicotiana tabacum) seedlings (Bonfig et al, 2007), a role in adult plants is still elusive. Recently, antisense suppression of soluble acid invertase in muskmelon (Cucumis melo) has revealed destructive effects on chloroplast ultrastructure that point to an involvement in the regulation of primary photosynthetic processes and would agree with a role in stabilizing sugar phosphate pools (Yu et al, 2008).…”

Evidence That High Activity of Vacuolar Invertase Is Required for Cotton Fiber and Arabidopsis Root Elongation through Osmotic Dependent and Independent Pathways, Respectively

“…High VIN expression or activity has been observed in a range of expanding tissues, including maize (Zea mays) ovaries (Andersen et al, 2002;McLaughlin and Boyer, 2004), grape (Vitis vinifera) berry (Davies and Robinson, 1996), carrot (Daucus carota) taproot (Tang et al, 1999), and sugar beet (Beta vulgaris) petioles (González et al, 2005). It is hypothesized that VIN may play a major role in plant cell expansion, a key step in plant cell development (González et al, 2005).…”

“…It is hypothesized that VIN may play a major role in plant cell expansion, a key step in plant cell development (González et al, 2005). However, progress in determining the roles of VIN in cell expansion suffers from several experimental limitations.…”