The properties of two strains of carrot (Daucus carota) callus are presented. One has a very low acid invertase activity which is accompanied by differences in morphology and metabolic rate, but not in growth rate. We conclude that one of the main functions of plant acid invertases is in controlling the levels of sugars which, by interaction with hormones, affect differentiation, both morphological and biochemical. The effect of tris on sucrose metabolizing enzymes, and the cause of the "sucrose effect" are considered.

The effect of ionic strength and pH on the solubility of acid invertase (E.C. 3.2.1.26.) and α-glucosidase (E.C. 3.2.1.20.) from carrot Daucus carota L. tissue cultures is presented. The action of these two factors on disrupted tissue is contrasted with the effects of the same treatment on the solubility of these enzymes from intact tissue. The results are discussed in terms of a unified theory on the solubility behaviour of acid invertase and other hydrolytic enzymes in plant cells.

Solubilization of acid invertase associated with cell wall preparations from aged slices of Jerusalem artichoke tuber tissue was achieved at high ionic

Journal Article Sucrose Suppression of Chlorophyll Synthesis in Carrot-Tissue 2: THE EFFECT OF COMPOSITION OF THE CULTURE MEDIUM Get access J. EDELMAN, J. EDELMAN Biology Department, Queen Elizabeth CollegeLondon, W.8 Search for other works by this author on: Oxford Academic PubMed Google Scholar A. D. HANSON A. D. HANSON Biology Department, Queen Elizabeth CollegeLondon, W.8 Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Experimental Botany, Volume 23, Issue 2, May 1972, Pages 469–478, https://doi.org/10.1093/jxb/23.2.469 Published: 01 May 1972 Article history Received: 28 July 1971 Published: 01 May 1972

Green carrot callus cultures when exposed to (14)CO2 in a liquid medium showed ligh-dependent (14)C-incorporation into sucrose, glutamine and malic acid. About 5% of total (14)C fixed in a 3 h period appeared in these products in the bathing medium; this was not due to tissue damage. Kinetic studies showed that the release occurred from a metabolic and not a storage compartment. The effects of DCMU, temperature and fluoroacetate demonstrated that release from this compartment was under respiratory and not photosynthetic control.

Substrate levels of sucrose were shown to reduce chlorophyll synthesis in carrot tissue culture strain CRT1 but not in strain CRT2. In CRT1 the effect was shown to be a suppression of greening specifically by sucrose rather than a reducing sugar requirement for chlorophyll synthesis. In CRT1 sucrose caused both a reduction in chloroplast numbers per cell and a suppression of lamellar development in plastids. This effect on chloroplast structure was consistent with the observed reduced photosynthetic efficiency (micromoles CO2 per hour per mg chlorophyll) of CRT1 calluses grown on sucrose.

Free space invertase activities were determined in carrot callus strains CRT1 and CRT2 grown under conditions in which sucrose suppression of chlorophyll synthesis occurred in CRT1 but not CRT2. CRT2 possessed a high free space acid invertase activity (pH optimum 5.0 Km for sucrose 3.1×10-3M) while CRT1 lacked this enzyme. [U-14C] sucrose introduced into the free space of calluses was rapidly inverted by CRT2, but not by CRT1.

14CO2-fixation rates in green carrot callus cultres (about 35 μg chlorophyll/g fresh wt) were determined in gaseous and liquid media using a range of light intensities and CO2 concentrations. Main products of light-dependent CO2-fixation were sucrose, alanine, glutamine, serine/glycine and malic acid. In darkness, glutamine and malic acid were formed.

Translocation of 14C-labelled photosynthate across 2 cm long carrot calluses was not detectable even 6 hours after a 30 min 14CO2 pulse. This is consistent with the discontinuous nature of the phloem as a whole, although small strands of contiguous, well differentiated sieve cells with companion cells were readily seen in electron micrographs.

Ageing slices of artichoke tuber or carrot root produced a substance, characterised as a protein, which when added to freshly cut slices inhibited invertase development. For maximum effect, it was necessary to expose the tissue to inhibitor immediately on excision, and this resulted in a slower rate of enzyme production and a lower final level. We suggest that there is an interaction between gibberellin, whose production is initiated by wounding, and the inhibitor. Bacterial infection was not the cause of the results obtained.

SummaryThe physiological behaviour of the fructose polymers, which are the sole carbohydrate reserve in Jerusalem artichoke tubers, is briefly described. It is suggested that certain enzymes which have been isolated from this tissue can account for these changes, and a theory of their integrated action is put forward: this involves the trisaccharide IF‐fructosylsucrose, widely found in fructosan‐containing tissues, as a key intermediate, and the enzyme which produces it from sucrose as a controlling biochemical factor. Sucrose itself, both as a substrate and by its direct effect on the other enzymes, also acts as a major means of control. The hypothesis does not involve sugar phosphates or nucleotide sugars, and seems to be applicable to other plants which contain fructosans.

The breakdown of starch in potato tubers which starts when buds begin to grow, stops if the sprouts are removed. The sprout controls the utilization and translocation of food reserves from the tuber. Movement of reserves can occur over the whole cross section of the tuber and is not restricted to the vascular shell. The presence of a growing sprout does not affect the permeability of the tuber tissue to sugar or amino acid.

A substance, characterised as a protein, is secreted into the medium by ageing tissue slices. When it was added to the medium in which freshly prepared slices were aged, subsequent invertase synthesis was partially inhibited.

A cell-free system which synthesizes protein was isolated from `aged' discs of Jerusalem artichoke tubers. The synthetic activity was largely associated with the fraction containing mitochondria. Preparations from freshly cut tissue were virtually inactive but increasingly active preparations were obtained from discs `aged' for progressively longer periods; those from 24 hour discs showing maximum activity. The characteristics of this change are reminiscent of the rate of development of invertase, a marker for protein synthesis in the intact disc. Extensive investigations showed that bacterial contamination was not a significant factor in the synthetic activity.

Research Article| October 01 1964 The metabolism of fructose polymers in plants. 4. β-fructofuranosidases of tubers of Helianthus tuberosus L J Edelman; J Edelman Search for other works by this author on: This Site PubMed Google Scholar TG Jefford TG Jefford Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1964) 93 (1): 148–161. https://doi.org/10.1042/bj0930148 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation J Edelman, TG Jefford; The metabolism of fructose polymers in plants. 4. β-fructofuranosidases of tubers of Helianthus tuberosus L. Biochem J 1 October 1964; 93 (1): 148–161. doi: https://doi.org/10.1042/bj0930148 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1964 The Biochemical Society1964 Article PDF first page preview Close Modal You do not currently have access to this content.

Journal Article The Metabolism of Fructose Polymers in Plants: II. EFFECT OF TEMPERATURE ON THE CARBOHYDRATE CHANGES AND MORPHOLOGY OF STORED TUBERS OF HELIANTHUS TUBEROSUS L. Get access T. G. JEFFORD, T. G. JEFFORD Department of Plant Physiology, Imperial College of Science and TechnologyLondon, S.W. 7 Search for other works by this author on: Oxford Academic PubMed Google Scholar J. EDELMAN J. EDELMAN Department of Plant Physiology, Imperial College of Science and TechnologyLondon, S.W. 7 Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Experimental Botany, Volume 14, Issue 1, February 1963, Pages 56–62, https://doi.org/10.1093/jxb/14.1.56 Published: 01 February 1963 Article history Received: 09 June 1962 Published: 01 February 1963