Metabolic control of seedling development by invertases

Abstract

Invertases are important enzymes in higher plants, which are involved in regulating developmental processes and responses to external factors. In a functional approach the role of invertases was investigated using transgenic plants ectopically expressing inhibitor proteins to decrease invertase activity. For generating specific effects, these inhibitor proteins were expressed in Arabidopsis under the control of synthetic promoters consisting of tetramers of pathogen-inducible elements, which were reported to yield low constitutive expression. Unexpectedly, seedling growth of putative transgenic plants was arrested at the four-leaf stage. Analysis of β-glucuronidase activity of corresponding reporter gene lines showed a correlation of the growth arrest with high activity of these promoters in seedlings grown under tissue culture conditions. The negative effect of invertase inhibition on seedling growth was substantiated by transgenic tobacco plants expressing an invertase inhibitor under control of a tetracycline inducible promoter. Ectopic induction of the invertase inhibitor during early seedling development resulted in a reduced fresh weight of seedlings. The importance of invertase in seedling development is further supported by results of expression profiling of invertases in Arabidopsis, which was confirmed by expression analyses. The mRNA for the vacuolar invertases Atßfruct3 and Atßfruct4 and cell wall invertase AtcwINV1 are specifically and strongly expressed during seedling development. These complementing results show that invertase activity is required for normal seedling development.

Orchestration of transpiration, growth and carbohydrate dynamics in rice during a dry-down cycle

“…Ji et al 2005b). CIN activity in meristematic and growing tissues indeed provides cells with hexoses for growth (Ji et al 2005b), a process that is known to be regulated through sugar (sucrose) signalling (Black et al 1995;Roitsch et al 2000;Sherson et al 2003;Heyer et al 2004;Roitsch and Gonzales 2004;Waclawovsky et al 2006;Bonfig et al 2007). Mild drought caused a transitory but significant increase in hexose concentration in sink leaves, followed by a strong decrease under severe stress (Fig.…”

“…The former, coding apoplastic cell wall invertases, are known to be crucial for the provision of hexoses to cells of meristems (Heyer et al 2004) and growing tissues (Black et al 1995;Yang et al 2003b;Liu et al 2004aLiu et al , 2005bRoitsch and Gonzales 2004;Bonfig et al 2007), and subject to regulation by sugar signalling (Black et al 1995;Roitsch et al 2000;Roitsch and Gonzales 2004). Some of the eight OsCIN genes of rice are highly organ specific (Cho et al 2005;Ji et al 2005aJi et al , 2005bLuquet et al 2007) and may play a role in regulating organ initiation and development, and consequently, in the sink activity related to it (Black et al 1995;Roitsch et al 2000;Bonfig et al 2007). Vacuolar invertase genes of rice (OsVIN1 and 2), however, are less organ specific (Cho et al 2005;Ji et al 2005a).…”

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).…”

Cloning and molecular characterization of putative invertase inhibitor genes and their possible contributions to cold-induced sweetening of potato tubers

“…Extensive research on invertase regulation has focused on the transcriptional level (Long et al 2002;Eason et al 2007;Proels and Roitsch 2009). However, emerging evidences indicate that invertase activity may be subject to posttranslational suppression by its inhibitory protein (Greiner et al 1999;Bonfig et al 2007;Jin et al 2009). …”