Enzymaktivitäten im Siebröhrensaft von Robinia pseudoacacia L. und anderer Baumarten

Kennecke, Mario; Ziegler, H.; Fekete, M. A. R. de

doi:10.1007/bf00380234

Cited by 35 publications

(11 citation statements)

References 28 publications

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“…The proteins are produced continuously and are carried along by the mass flow in the sieve tubes. The concentration of STEPs of Ricinus seedlings (0.1-0.2 mg. m1-1) is similar to that found in the phloem exudate of Oryza (0.15 0.2 mg. ml-1; M. Chino, Department of Agricultural Chemistry, University of Tokyo, Tokyo, Japan, personal communication), and Tilia (0.3 mg. ml-1; Kennecke et al 1971), but very different from that of Cucurbita (10 mg 9 ml-1; Kollmann et al 1970).…”

Section: Discussionmentioning

confidence: 95%

Specific proteins in the sieve-tube exudate of Ricinus commuais L. seedlings: separation, characterization and in-vivo labelling

Sakuth

Schobert

Pécsváradi

et al. 1993

Planta

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Abstract. Ricinus communis L. seedlings exuded pure phloem sap from the cut hypocotyl for several hours. Throughout the entire exudation period proteins were present in the phloem exudate at a constant concentration ranging from 0.11 to 0.41 mg. ml 1 depending on the culture conditions and the age of the seedlings. Manipulation of the nutrient supply at the cotyledons after removal of the endosperm did not change the protein concentration in the exudate. Comparison of sieve-tube exudate proteins (STEPs) with soluble proteins extracted from the hypocotyl and the cotyledons showed a unique abundance of small proteins in the exudate, with molecular weights ranging from 10 to 25 kDa. Bands at 18, 19 and 20kDa were especially dominant. The proteins found transiently in the xylem exudate, which might represent proteins secreted at the wound surface, were different in pattern. Two-dimensional separation of STEPs revealed that more than 100 distinct polypeptides occurred in the sieve-tube exudate, most of them slightly acidic with isoelectric points ranging from 4 to 6 and a few basic ones around 8.[35S]Methionine fed to the cotyledons led to labelling of STEPs, demonstrating their rapid synthesis. It is concluded that there is a continuous synthesis and translocation of specific sieve-tube proteins, whose function is unknown.

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Section: Discussionmentioning

confidence: 95%

Specific proteins in the sieve-tube exudate of Ricinus commuais L. seedlings: separation, characterization and in-vivo labelling

Sakuth

Schobert

Pécsváradi

et al. 1993

Planta

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“…Similarly, sucrose phosphate synthase activity (assayed as described by Lowell et These data confirm the hypothesis that sucrose synthase activity is locally elevated in vascular tissues of this system and provide evidence at the level ofenzyme activity consistent with that of promoter analysis for one of the sucrose synthase genes (19) and of immunohistology (1) in other species. Previous attempts to obtain such information (3,6,8,12) have been complicated by potential differences in tissue protein levels, incomplete isolation of vascular strands, and/or a lack of comparative data from adjacent tissues.…”

Section: Resultsmentioning

confidence: 99%

“…The suggestion that sucrose synthase activity is a good indicator of sink strength (2, 17) thus should be modified or refined to account for the locally elevated activity of sucrose synthase in vascular bundles of this (Table I) and probably other systems (1,3,8,12,19). Although sucrose synthase is present in sink cells of citrus fruit (Table I), its significantly greater activity in vascular strands indicates a vascular function in addition to its proposed involvement in metabolism of importing cells.…”

Section: Resultsmentioning

confidence: 99%

Sucrose Synthase and Invertase in Isolated Vascular Bundles

Tomlinson¹,

Duke²,

Nolte³

et al. 1991

Plant Physiol.

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The role of sucrose synthase in translocation and sucrose partitioning remains unresolved despite extensive study of its association with elevated carbon import. 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. However, other studies have indicated expression of sucrose synthase genes may be more complex and appears to be sensitive to changes in metabolism and/or environment (14, 15). Nonetheless, immunohistological evidence has indicated a greater abundance of sucrose synthase protein in vascular areas of young roots (1). The levels of total protein also tend to be greater in vascular tissues (13), however, leaving the extent of sucrose synthase activity in vascular tissues unresolved.The possibility that sucrose synthase activity may be greater in vascular bundles has been difficult to address because few opportunities exist for isolation of vascular strands (4). Most plant tissues have fine networks of vascular bundles that cannot be effectively separated from adjacent parenchymal cells. Hawker and Hatch (6) MATERIALS AND METHODS'Marsh' grapefruit (Citrus paradisi Macf.) were sampled from the outer, southern canopy of 55-year-old trees in a commercial orchard in Lake Wales, FL, during late August to early September (before completion of the expansive phase of growth) during four consecutive growing seasons. Samples for immediate dissection were also obtained during the fourth growing season from 10-year-old containerized trees grown in Gainesville, FL. Results from these fruit were similar to those from the orchard-grown trees and were included in overall means.Fruit were washed, sectioned longitudinally, peeled, and separated into individual segments. These were dissected into tissues pictured in Figure 1

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“…In this context various enzyme activities could be detected in the phloem sap (Kennecke et al, 1971;Eschrich et al, 1972;Eschrich and Heyser, 1975;Geigenberger et al, 1993;Yoo et al, 2002). More recent results suggest that SEs even contain complete sets of enzymes to perform complex biosynthetic reactions.…”

Section: Introductionmentioning

confidence: 95%