Pyrophosphate Dependent Phosphofructokinase of Citrullus lanatus: Molecular Forms and Expression of Subunits

During germination and seedling establishment, the total pyrophosphate-dependent phosphofructokinase (PFP) activity in the cotyledons increases. Two types of subunits with molecular weights of 68 (α-subunit) and 65 (β-subunit) kilodaltons are present. The increase in activity coincides with an approximately 10-fold increase in β-subunit and twofold increase in α-subunit content. Different isoforms of PFP are present at all stages of incubation, but the ratio between the isoforms significantly changes. A linear relationship exists between the ratio of the two PFP subunits and the ratio of the two isoforms of the enzyme. The more anionic (peak 2) isoform of the enzyme apparently is favored by a high ratio of total β-subunit to α-subunit content. The β- to α-subunit ratio of the peak 2 isoform is also approximately fivefold higher than that of the peak 1 (less anionic) isoform. It is evident that the two subunits are not coordinately expressed and the level of expression of each subunit appears to be the primary factor determining the molecular form in which the enzyme is present. In some tissues, only the 65 kilodalton polypeptide is expressed in large amounts. The peak 1 isoform has a higher affinity for pyrophosphate than the peak 2 isoform, while the affinity for fructose-6-phosphate is similar. Both molecular forms are activated by fructose-2,6-bisphosphate.     

Constitutive Expression of Stress-Inducible Genes, Including Pathogenesis-Related 1 Protein Gene in a Transgenic Interspecific Hybrid of Nicotiana glutinosa x Nicotiana debneyi

Constitutive expression of a type of stress-inducible proteinsincluding pathogenesisrelated (PR) 1 protein and ubiquitin-relatedprotein in an interspecific hybrid of Nicotiana glutinosa xNicotiana debneyi was noted. In the two parental species andin tobacco, these proteins are not expressed in healthy plantsbut they are induced by stresses such as the formation of locallesions after viral infection and treatment of salicylic acid.A second type of stress-inducible genes, such as the genes forbasic ß-1,3-glucanase and putative proteinase inhibitorwere regulated normally, and were not expressed constitutivelyin the hybrid. In the transgenic hybrid, into which a chimericgene consisting of 5' upstream of tobacco PRla gene and ß-glucuronidase(GUS) gene was introduced, very high GUS activity was expressedconstitutively even at healthy state. An abnormal response bythis hybrid to plant hormones was also noted. A possible mechanismfor the unregulated expression of the stress-inducible genesin the interspecific hybrid is discussed. (Received September 13, 1991; Accepted December 27, 1991)     

The Mode of Expression and Promoter Analysis of the arcA Gene, an Auxin-Regulated Gene in Tobacco BY-2 Cells

The arcA, a member of the G protein rß-subunit family,was isolated from tobacco BY-2 cells as an auxin-responsivegene. Characterization of arcA, which should help to elucidatethe function of the gene product in the plant cells, was performedwith emphasis on the mode of expression and the analysis ofits promoter. Accumulation of the arcA message was detectedonly after treatments with auxins and not after treatments withother phytohormones or CdCl₂, implying that responsiveness ofarcA was exclusive to auxin. The putative arcA promoter regionwas fused to a reporter gene for rß-glucuronidase(GUS), and transient expression was analyzed in tobacco BY-2cells. Two series of arcA promoter/GUS chimeric genes were constructed.One consisted of a set of 5' nested deletions of the arcA promoterconnected to the gene for GUS and the other consisted of a varietyof the arcA promoter fragments fused to a minimal promoter-GUSconstruct. The results indicated that the promoter sequencecovering four sets of direct repeats (– 562 to –167)was necessary for the sufficient response of arcA promoter toauxin in BY-2 cells. Moreover, irrespective of auxin treatment,elevated activity of GUS driven by this promoter fragment wasdetected, a result that implies that this region behaves anenhancer in BY-2 cells. (Received September 30, 1995; Accepted March 1, 1996)     

Development of {beta}-amylase activity and polymorphism in wheat seedling shoot tissues8

Increasing ß-amylase activity in wheat (Triticum aestlvum,var. Star) seedling shoot tissues was consistently accompaniedby the development of a characteristic polymorphism of the enzyme,as shown by electrophoresis employing amylopectin-containingpolyacrylamide gels. Very young shoot tissue contained one principalform of the enzyme (ß1), whereas two other major forms(ß2, ß3) appeared complementary to thisupon further growth. In vitro incubation experiments indicatedthat the polymorphism arose via a probably proteolytic conversionof ß1 into ß2 and ß3. The conversioninvolved neither an activation of ß-amylase nor asignificant modification of ß-amylase component plvalues. The electrophoretic ß-amylase patterns ofsubcellular leaf compartments suggested that ß1 issynthesized in the cytoplasm of leaf mesophyfi cells and thatthe other forms arise upon transfer of this ‘primary’form into the vacuole. The development of shoot ß-amylaseactivity did not require light, but appeared to be under thenegative control of the chloroplast and was stimulated by mineralnutrients. No clear relationship between ß-amylaseactivity and starch metabolism was evident, since the leaf activitywas largely absent from mesophyll protoplasts, could not beunequivocally demonstrated in the mesophyll chioroplasts, anddeveloped regardless of whether the tissues contained significantamounts of starch or not. Key words: Wheat, leaves, ß-amylase, polymorphism, compartmentation     

Regulated Expression of a Gene-Fusion Product Derived from the Gene for Phytochrome I from Pisum sativum and the uidA Gene from E. coli in Transgenic Petunia hybrida

The 5'-upstream region (2.4 kb) of the gene for phytochromeI from Pisum sativum (phyl) was fused to the uidA gene fromEscherichia coli that encodes ß-glucuronidase (GUS).The resulting PHY-GUS fusion was introduced into Petunia hybridaand was used as a reporter of the expression of the phyI genewhich was recognized by GUS activity. The PHY-GUS fusion wasexpressed at a relatively high level when transgenic plantswere grown in the dark, while leaves and stems of light-grownplants showed background activity. Flowers of light-grown plantswere shown to have significant levels of GUS activity but rootsdid not have such activity. When light-grown transgenic plantswere transferred to the dark, they expressed the activity atlevels that corresponded to those of dark-grown plants. Lighttreatment prior to growth in darkness revealed red/far-red reversibilityof recovery of the activity. Thus, the 2.4-kb fragment fromthe 5' region of the phyI gene carries the information necessaryfor the light-repressible autoregulation. (Received March 30, 1991; Accepted May 20, 1991)     

Modulation of Elicitor-Induced Chitinase and {beta}-1,3-Glucanase Activity by Hormones in Phaseolus vulgaris

Chitinase and ß-1 ,3-glucanase induction in Phaseolusvulgaris by cell wall elicitor from Col-letotrichum lindemuthianumhas been studied together with the effects of the hormones IAAand ethylene. Chitinase and ß-1, 3-glucanase increasedin response to the elicitor in the resistant cultivar, Kievit,but not in the susceptible cultivar, Pinto. However, both activitiesincreased in both cultivars in response to hormones in the absenceof elicitor; elicitor did not augment this response in cv. Kievit.Aminoethoxyvinyl glycine (AVG) abolished all responses exceptthose obtained by the application of ethylene. Of other hydrolasestested, only ß -galactosidase was induced by elicitor;this was similar for both cultivars but hormones were withouteffect. Evidence suggests that both chitinase and ß-l,3-glucanase are located within the cell rather than in theintercellular space. It is concluded that chitinase and ß;-l,3-glucanaseare coordinately synthesized as a defence response since theyhydrolyse complementary linkages in pathogen derived polysac-charides.Regulation of the induction of the two enzymes is primarilydue to ethylene and the lack of response in the compatible reactionappears to arise from an inability to synthesize ‘ stress’ ethylene. ¹Present address: School of Chemistry, Molecular and Biological Sciences, University of Sussex, Brighton BN1 9QJ, U.K. (Received March 15, 1991; Accepted June 13, 1991)     

Production of Cellulolytic Enzymes by Botryodiplodia theobromae, Pat.

Carboxymethylcellulase (CM-cellulase) and ß-glucosidaseactivities were induced in cultures of Botryodiplodia theobromae,Pat. Both growth of the fungus and CM-cellulase production werebetter with sodium nitrate as nitrogen source than with eitherammonium nitrate or ammonium chloride. Growth, per unit nitrogensupplied, was greater with glutamic acid and aspartic acid asnitrogen sources than with sodium nitrate; this was probablybecause the fungus utilized the carbon of these amino-acids.Most ß-glucosidase activity was formed with ammoniumchloride or ammonium nitrate as nitrogen source. Glucose inhibited the activity of ß-glucosidase markedly.Low glucose concentration (c. 0.003 M) stimulated CM-cellulaseactivity but concentrations above 0.05 M inhibited. The formationof both enzymic activities was repressed in the presence ofglucose. ß-glucosidase activity was more thermolabilethan that of CM-cellulase.     

Maternal Effects of mto1 Mutation, That Causes Overaccumulation of Soluble Methionine, on the Expression of a Soybean {beta}Conglycinin Gene Promoter-GUS Fusion in Transgenic Arabidopsis thaliana

ß-Conglycinin, the 7S seed storage protein of soybean(Glycine max [L.] Merr.), is comprised mainly of three subunits,designated , ' and ß. Expression of the gene encodingthe ß subunit is unique because its expression hasbeen shown to be down-regulated by exogenously applied L-methioninein immature soybean cotyledon cultures in vitro. Arabidopsisthaliana strain carrying a mto1-1 mutation overaccumulates solublemethionine. By using this mutant, we analyzed the effects ofmethionine on expression of the ß subunit gene invivo. Reciprocal crosses were made between the mto1-1 mutantand a transgenic A. thaliana strain, designated SNTß3,which carries a ß-glucuronidase (GUS) reporter geneunder the control of the promoter region of the ßsubunit gene. Analysis of GUS activity in F₁ seeds indicatedthat the GUS activity was dramatically repressed when the mto1-1mutant plants were used as female parents. We constructed astrain which carries both the transgene and mto1-1 mutationin the homozygous state. Analyses of the GUS activity in seedsof this double homozygous strain indicated that the GUS activitywas repressed to 2.5% of control by introduction of the mto1-1mutation. These results indicate that the ß subunitgene promoter activity in seeds is down-regulated by maternalgenotype and suggest that soluble methionine, or its mobilemetabolite, is translocated from mother plants to repress ßsubunit gene expression in seeds. ⁵Present address: Division of Biological Sciences, GraduateSchool of Science, Hokkaido University, Kita-ku, Sapporo, 060Japan ⁶Present address: Department of Biotechnology, Faculty of Agriculture,The University of Tokyo, Bunkyo-ku, Tokyo, 113 Japan     

Synthesis of O-glycan core 3: Characterization of UDP-GlcNAc: GalNAc-R {beta}3-N-acetyl-glucosaminyltransferase activity from colonic mucosal tissues and lack of the activity in human cancer cell lines

UDP-GlcNAc: GalNAc-R ß3-GlcNAc-transferase (core 3ß3-GlcNAc-T, where GlcNAc is N-acetyl-D-glucosamine,GalNAc is N-acetyl-D-galactosamine and T is transferase) isexpressed in a tissue-specific fashion and is high in normalcolonic tissue, but downregulated in colon cancer. To furtherstudy the control of this enzyme, we examined the activity inpig, rat and human colonic tissues, and several human cancercell lines. The enzyme was difficult to solubilize by detergentsand was extremely unstable in the solubilized form. Using syntheticderivatives of the GalNAc-R substrate, we showed that the specificityof the enzyme in normal rat and human colonic mucosa requiresall the substituents of the GalNAc-sugar ring of substratesfor maximal activity. Core 3 ß3-GlcNAc-T was significantlyinfluenced by the structure of the aglycon group. None of theinactive substrate derivatives could inhibit the activity. N-Iodoacetamido-galactosamine     

Isolation of prolegumin from developing pea seeds: its binding to endomembranes and assembly into prolegumin hexamers in the protein storage vacuole

A fraction enriched in endoplasmic reticulum and Golgi membranesfrom developing cotyledons of Pisum sativum L. has proved tobe a convenient source for the isolation of prolegumin, theprecursor of the major 11S storage globulin of pea seeds. Twopro-proteins were isolated with molecular masses of 60 kDa and75 kDa, respectively. A monoclonal antibody, designated 2B1,against prolegumin was raised using the in vitro immunizationtechnique. This antibody recognizes the 60 kDa precursor polypeptide,but only the 20 kDa ß-subunit of mature legumin. Prolegumin,like the ß-subunit of the mature legumin, is a hydrophobicprotein. After import into the protein storage vacuole, andafter formation of the protein bodies trimeric 9S proleguminassembles into 12S hexamers without prior processing of theprecursor. Since prolegumin in vitro does not oligomerize intomore than 9S tnmers these results suggest that a protein-mediatedassembly of 9S prolegumin trimers into 12S prolegumin hexamersprobably occurs in the lumen of the protein storage vacuole.Prolegumin, but not mature legumin, binds very tightly to membranes.This property points to a possible way of identifying a putativeprolegumin receptor. Key words: Calcium, Endoplasmic reticulum, Golgi apparatus, legumim, monoclonal antibody, pea cotyledons     

Studies on the {beta}-glucosidase System of Trifolium repens L.

Using DEAE-cellulose two distinct ß-glucosidase enzymeshave been identified in white clover; one form is primarilyassociated with the seed, the other with young leaves. Evidenceis presented for the separate nature of ß-glucosidaseand ß-galactosidase activity in dry seed flour andin young leaf tissue. These results are considered in relationto the function of the Li locus in white clover, which is shownto control both ß-glucosidase and ß-galactosidaseactivity in expanding leaves.     

Levels of {beta}-Glucan and Lignin in Elongating Internodes of Deepwater Rice

Partial submergence or treatment with either ethylene or gibberellicacid (GA₃ induces rapid growth in deepwater rice (Oryza sativaL.). We correlated the synthesis of two cell wall componentswith two phases of internodal elongation, namely (13,14)-ß-glucanformation with cell elongation and lignification with differentiationof the secondary cell wall and cessation of growth. The contentof ß-glucan was highest in the zone of cell elongationin internodes of air-grown plants and plants that were inducedto grow rapidly by submergence. In the intercalary meristemand in the differentiation zone of the internode, ß-glucanlevels were ca. 70% lower than in the zone of cell elongation.The outer cell layers, enriched in epidermis, contained moreß-glucan in submerged, rapidly growing internodesthan in air-grown, control internodes. The ß-glucancontent of the inner, parenchymal tissue was unaffected or slightlylowered by submergence. The epidermis appears to be the growth-limitingstructure of rapidly growing rice internodes. We hypothesizethat elevated levels of ß-glucan contribute to elongationgrowth by increasing the extensibility of the cell wall. Lignificationwas monitored by measuring the content of lignin and the activitiesof two enzymes of the lignin biosynthetic pathway, coniferylalcohol dehydrogenase (CAD) and phenylalanine ammonia-lyase(PAL), in growing and non-growing regions of the internode.Using submerged whole plants and GA₃-treated excised stem segments,we showed that lignin content and CAD activity were up to sixfoldlower in newly formed internodal tissue of rapidly growing ricethan in slowly growing tissue. No differences were observedin parts of the internode that had been formed prior to inductionof growth. PAL activity was reduced throughout the internodeof submerged plants. We conclude that lignification is one ofthe processes that is suppressed to permit rapid growth. ¹ This work was supported by the National Science Foundationthrough grants No. DCB-8718873 and DCB-9103747 and by the Departmentof Energy through grant No. DE-FGO2-90ER20021. M.S. was therecipient of a fellowship from the Max Kade Foundation.     

Isolation, characterization and inactivation of the mouse Mgat3 gene: the bisecting N-acetylglucosamine in asparagine-linked oligosaccharides appears dispensable for viability and reproduction

The biosynthesis of complex asparagine (N)-linked oligosaccharidesin vertebrates proceeds with the linkage of N-acetylglucosamine(GlcNAc) to the core mannose residues. UDP-N-acetylglucosamine:ß-D-mannosideß1–4 N-acetylglucosaminyltransferase III (GlcNAc-TIII,EC2.4.1.144) catalyzes the addition of GlcNAc to the mannosethat is itself ß1–4 linked to underlying N-acetylglucosamine.GlcNAc-TIII thereby produces what is known as a ‘bisecting’GlcNAc linkage which is found on various hybrid and complexN-glycans. GlcNAc-TIII can also play a regulatory role in N-glycanbiosynthesis as addition of the bisecting GlcNAc eliminatesthe potential for     

Mutations in {beta}-Tubulin Block Transhyphal Migration of Nuclei in Dikaryosis in the Homobasidiomycete Coprinus cinereus

ß-Tubulins from fourteen benomyl-resistant strainsof the homobasidiomycete Coprinus cinereus, which carry thebenA, benB, benC or benD mutations, were analyzed by urea SDS-PAGEor isoelectric focusing and subsequent immunoblot analysis.Electrophoretic aberrations in a major ß-tubulin isotype,denoted ß1 were found in two strains, BEN154 and BEN215,both of which carry benomyl resistance mutations in benA ⁺ Theaberrations of ß1 in BEN154 and BEN215 cosegregatedwith benomyl resistance among the progeny of outcrosses of BEN154 and BEN215 to wild type, indicating that the ß1aberrations were caused by the benA mutations. Both the mutantand wild-type ß1 tubulins were present in the heterozygousdikaryons, BEN 154/wild-type and BEN215/wild-type, ruling outpost-translational modification as a possible cause for theaberrations in ß1. Thus, we conclude that benA isa structural gene for ß1. Transhyphal migration ofnuclei in dikaryosis was blocked in the mycelia of BEN 154 andin its progeny that carried benA (ß1 mutation), demonstratingthat microtubules are involved in the migration process. Nuclearmigration in dikaryosis seems to differ in terms of mechanism,at least in part, from the migration of tetrad nuclei from basidiainto prespores during formation of basidiospores and from themigration of nuclei from basidiospores into hyphae during germination,because a benA mutation blocked the former without affectingthe latter two processes. (Received May 19, 1989; Accepted August 30, 1989)     

Alkaline phosphatase activity of Skeletonema costatum populations in the Trondheimsfjord

During May and June of 1975 and 1976, unialgal blooms of themarine diatom Skeletonema costatum in the Trondheimsfjord exhibitedsignificant alkaline phosphatase activity, as measured by afluorometric method. The fairly high activities of some populationscorrelated well with clear indications of P-limitation obtainedby measurement of N/P, ß-l,3-glucan/P and protein/ß-l,3-glucanratios. Very few significant activities were measured in populationswith a cellular N/P ratio below 14, which agrees well with anN to P ]balance point’ of 11-12 for S. costatum. The activitywas detected in brackish water with S <30 and was foundto be closely related with the cellular phosphorus content,low content leading to high phosphatase activity. The ratioof phosphatase activity to cellular phosphorus is proposed asa sensitive parameter for phosphorus-limited growth. No enzymeactivity could be detected in coastal waters outside the fjord.     

A novel {beta}-galactosidase gene isolated from the bacterium Xanthomonas manihotis exhibits strong homology to several eukaryotic {beta}-galactosidases

The gene encoding a ß-galactosidase from Xanthomonasmanihotis was cloned into Escherichia coli. The gene resideson a 2.4 kb DNA fragment which was isolated from a partial Sau3Alibrary in the cloning vector pUC19 using 5-bromo-4-chloro-3-indolyl-ß-D-galactopyranoside(X-gal) as the selection. The enzyme produced by the clone hasa specificity for ß1-3->ß1-4-linked galactose.The nucleotide sequence of the gene was determined. The deducedprotein sequence contained 597 amino acids yielding a monomericmolecular mass of 66 kDa. The cloned ß-galactosidaseshowed no similarity to any known prokaryotic ß-galactosidase.However, extensive similarity was observed with eukaryotic ß-galactosidasesfrom animals, plants and fungi. The strongest similarity waswith the ß-galactosidases found hi the human and mouselysosomes (42 and 41% identity, respectively). Alignment ofthe X.manihotis and eukaryotic ß-galactosidase sequencesrevealed seven highly conserved domains common to each protein.Additionally, Domain 1 in X.manihotis showed similarity to regionswithin catalytic domains from seven xylanases and cellulasesbelonging to family 10 of glucosyl hydrolases. A region spanningDomain 2 showed similarity to the catalytic domain of endo ß1-3glucanases from tobacco and barley. cellulase ß-galactosidase G_M$$$gangliosidosis Morquio B syndrome Xanthomonas     

A Further Study of {beta}-Galactosidase Activity in Apples Ripening in Store

Apples (Malus domestica Borkh.) were ripened in 2% O₂ at 3·3°C. The loss of galactose residues from the cortical cellwalls was initiated after 27 d although an increase in the ß-galactosidaseactivity of the tissue did not occur until after 50 d. ß-Galactosidase activity associated with the cellwall was determined using discs of cortical tissue. A substantiallevel of activity was observed prior to picking and subsequentlyduring ripening of the apples in air.     

{beta}1,4-Galactosyltransferase activity in B cells detected using a simple ELISA-based assay

Lymphocytic ß1,4-galactosyltransferase (ß1,4-GalTase,EC 2.4.1.38 [EC] ) activity was measured in B cells using a neoglycoprotein,N-acetylglucosamine-phenylisothlocyanate-bovine serum albumin(GlcNAc-pITC-BSA), as an acceptor substrate in a novel enzyme-linkedimmunosorbent assay (ELISA)-based method. This assay provedto be much simpler to use than the lengthy and expensive radiochemicalassays commonly used, and has the additional advantage thatit specifically detects the enzyme mediating transfer via theGalß1,4GlcNAc linkage. A F(ab')₂ antibody againstGalTase was able to specifically inhibit the reaction. Greatersensitivity for ß1,4-GalTase activity was obtainedusing GlcNAc-pITC-BSA as an acceptor substrate rather than ovalbumin.Low levels of ß-galactosidase activity were detectablein lymphocyte cell lysates at acidic pH, although such activitywas not detectable at the neutral pH used in the ß1,4-GalTaseactivity assay. Using this assay with the GlcNAc-pITC-BSA acceptor,similar ß1,4-GalTase activities were observed in CD19⁺B cells from patients with rheumatoid arthritis (RA) to thoseseen in normal control individuals. ELISA ß1,4-galactosyltransferase lymphocyte neoglycoprotein radiochemical     

Intraspecific Variation in Oil Components ofBoronia megastigmaNees. (Rutaceae) Flowers

Intraspecific variation in the oil composition ofBoronia megastigmaNees.(Rutaceae) was examined. Boronia absolute is extracted fromblossom primarily for use as a food additive. A major componentis ß-ionone andB. megastigmais one of the commercial,natural sources of this compound. Genotypes superior in productionof ß-ionone and low in monoterpene hydrocarbons weresought from natural populations in the south west of WesternAustralia as part of a breeding programme. Flowers were collectedfrom 25 plants in each of 29 different populations. Blossomwas extracted with ethanol and analysed using a gas liquid chromatographfitted with ionisation detectors. The contents of ß-ionone,dodecyl acetate, -pinene, ß-pinene and limonene inthe oil extract were compared. Intra-population variation wasas great as inter-population variation and no distinct chemotypeswere found. Considerable variation existed in the content ofcomponents. The highest ß-ionone content was 1787mg g^-1f. wt. Some genotypes contained all five components analysed,others lacked one or more of the monoterpenes: -pinene, ß-pineneor limonene. Principle components analysis indicated that contentsof ß-ionone and dodecyl acetate were associated andthat they were distinct from the content of the monoterpenes,which were associated with each other. Natural shading was associatedwith lower levels of monoterpenes but other oils were unaffected.Young plants contained less pinenes than older plants and oldplants contained the most dodecyl acetate. Vigorous plants producedmore pinenes. Red flowers contained the least ß-iononeand dodecyl acetate.Copyright 1999 Annals of Botany Company Boronia megastigma,boronia, Rutaceae, oil, -pinene, ß-pinene, limonene, ß-ionone, dodecyl acetate, monoterpenes, chemotypes.     

Auxin-induced changes in the molecular weight of hemicellulosic polysaccharides of the Avena coleoptile cell wall

The average molecular weight of the water soluble hemicelluloses(hemicellulose B) of the Avena coleoptile cell wall was determinedby gel permeation chromatography (GPC) and viscometry. Analysisof the neutral sugar composition of henucellulose B eluted froma GPC column (Sepharose 4B) indicated that it consists of ß-glucanwith a high molecular weight and arabinoxylan with a low molecularweight. A kinetic study of the effect of auxin on the moleculardistribution of henucellulose B demonstrated that auxin decreasedthe ß-glucan content of the hemicellulose as earlyas the first hour incubation, but not the arabinoxylan content,when it stimulated the extension of the coleoptile segments.Calculation of the weight-average molecular weight from thechromatograms suggested that auxin decreased the molecular weightof hemicellulose B; this was also confirmed by viscometry. Thus,auxin may cause cell wall loosening, leading to cell extension,through its effect on ß-glucan degradation or throughthe decrease in the molecular weight of hemicellulose B. (Received July 16, 1979; )