摘要:

The in vivo metabolism of L‐tryptophan in wound‐activated andAgrobacterium tumefaciens, strain C 58, transformed tissues of white potato tubers (Solanum tuberosumL. cv. Saskia) was investigated. The following metabolites of L‐tryptophan were identified in both tissues by co‐chromatography with authentic standards in several thinlayer chromotography (TLC) and high pressure liquid chromatographic (HPLC) systems: indole‐3‐acetic acid (IAA), indole‐3‐acetaldehyde, indole‐3‐ethanol, indole‐3‐acetamide and tryptamine. Labelled indole‐3‐acetaldoxime was only found in transformed tissue. Crown gall tissue generally incorporated [14C]‐L‐tryptophan into precursors of IAA at a distinctly higher rate than did wound tissue. Tryptamine and indole‐3‐ethanol accumulated about ten‐fold more label in crown gall cells than in cells from wounded tissue. The incorporation of radioactivity into indole‐3‐acetamide as determined by 2 consecutive TLC systems followed by HPLC analysis was rather low, though consistently observed in both tissues. An indole‐3‐acetamide hydrolyzing enzyme, the putative product of gene 2 on the T‐DNA, could be extracted from the transformed tissue only. The indole‐3‐ethanol level was 4.3 nmol (g dry weight)−1and 41 nmol (g dry weight)−1for wounded tissue and primary crown gall tissue, respectively, as determined by HPLC with a [14C]‐labelled internal standard. The experiments are critically discussed in relation to recent reports on a T‐

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02307.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The effects of the addition and withdrawal of gibberellic acid (GA3) and Ca2+on enzyme synthesis and secretion by barley (Hordeum vulgareL. cv. Himalaya) aleurone layers were studied. Incubation of layers in GA3plus Ca2+affects the total amount of secreted α‐amylase (EC 3.2.1.1) and acid phosphatase (EC 3.1.3.2) by promoting the appearance of different isoenzymic forms of these enzymes. The release of α‐amylase isoenzymes 1–4 in response to GA3plus Ca2+has a lag of 6 h. When layers are incubated in GA3alone for 6 h prior to the addition of Ca2+, isoenzymes 1–4 appear in the medium after only 30 min. When the addition of Ca2+to layers pretreated in GA3is delayed beyond 12 h, its effectiveness in stimulating the synthesis and release of isoenzymes 3 and 4 is diminished. After 35 h of preincubation in GA3, addition of Ca2+will not stimulate synthesis of α‐amylase isoenzymes 3 and 4. Aleurone layers preincubated for 6 h in GA3will respond to Ca2+when the GA3is withdrawn from the incubation medium by producing α‐amylase isoenzymes 1–4. The converse is not the case, however, since layers preincubated in Ca2+for 6 h will not produce all isoenzymes of α‐amylase when subsequently incubated in GA3. The Ca2+‐stimulated release of α‐amylase from GA3pre‐treated layers is dependent on the time of incubation in Ca2+and the concentration of the ion. The response to Ca2+is temperature‐dependent, and other divalent cations such as Mg2+cannot substitute for Ca2+. We conclude that Ca2+influences α‐amylase release by influencing

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02308.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Respiratory characteristics of wheat (Triticum aestivumL. cvs Gabo and WW15), mung bean (Vigna radiataL. Wilczek cv. Celera) and sunflower (Helianthus annuusL. cv. Sunfola) were studied in plants grown under a normal CO2concentration and in air containing an additional 340 (or 250) μl l−1CO2. Such an increase in global atmospheric CO2concentration has been forecast for about the middle of the next century. The aim was to measure the effect of high CO2on respiration and its components. Polarographic and, with wheat, CO2exchange techniques were used. The capacity of the alternative pathway of respiration in roots was determined polarographically in the presence of 0.1 mMKCN. The actual rate of alternative pathway respiration was assessed by reduction in oxygen consumption caused by 10 mMsalicylhydroxamic acid.Each species responded differently. In wheat, growth in high atmospheric CO2was associated with up to 45% reduction in respiration by both roots and whole plants. Use of respiratory inhibitors in polarographic measurements on wheat roots implicated reduction in the degree of engagement of the alternative pathway as a major contributor to this reduced respiratory activity of high‐CO2plants. No change was found in the total sugar content per unit wheat root dry weight as a result of high CO2. In none of the species was there an increase in the absolute, or relative, contribution by the alternative pathway to total respiration of the root systems. Thus the improved photosynthetic assimilate supply of plants grown in high CO2did not lead to increased diversion of carbon through the non‐phosphorylating alternative pathway of respiration in the root. On the contrary, in wheat grown in high CO2the reduced loss of carbon through that route must have contributed to their larger dry

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02309.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Pea plants (Pisum sativumL.) possessing the slender phenotype (conferred by the gene combinationla crys) have extremely long, thin internodes and are phenotypically similar to dwarf plants (possessing genesLaand/orCry) that have been treated with a non‐limiting dose of gibberellin (GA3). In contrast to tall and dwarf plants, slender plants are virtually insensitive to treatment with AMO 1618, PP333 or GA3and addition of the “gibberellin‐less” mutant genenadoes not alter the phenotype of slender plants.Naslender segregates possessed lower levels of gibberellin‐like substances than comparable dwarf segregates when extracts from shoots were assayed using the lettuce hypocotyl or rice seedling bioassays. In addition,naslenders possessed little or no gibberellin‐like activity even though they possessed a slender phenotype. Thus the gene combinationla cryscauses slender plants to respond as if they are saturated with gibberellins for growth. In addition, the gene combinationsla crysandle la cryc(allelecrycis less extreme in effect thancrys) are shown to be almost completely epistatic to the alleles at thenalocus. All these results suggest that gibberellin levels are not important in determining the internode length of slender peas (genotypela crys). The possible mechanisms by which this could occur ar

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02310.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The Michaelis constants (Km) and activation energies (Ea) for allozymes of cytosolic phosphogluco‐isomerase (PGI‐2; EC 5.3.1.9) from ryegrasses (Lolium perenneL.,Lolium multiflorumLam. and interspecific hybrids) have been investigated. Differences were found between the allelic isozymes, but intra‐allelic variations were at least as large. The thermal stability of the isozymes also varied, with the most commonly occurring form (theb‐allozyme) having the highest stability at 50°C. Some possible explanations for these findings are discussed and the implications for plant breeders

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02311.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The formation of indoleacetylaspartic acid (IAAsp) and its metabolic significance were studied in the developing cotyledons and primary two leaves of cotton (Gossypium barbadenseL. cv. Giza 68, long staple). Levels of indoleacetic acid (IAA), IAAsp, bound IAA and degradation of tryptophan (Trp)‐carboxyl‐[14C] by enzyme extracts were estimated from leaf emergence to full expansion. The patterns were also followed in the two cotyledons before and after germination. The results suggest synthesis of IAAsp in response to either active Trp‐conversion or hydrolysis of bound IAA. Ester IAA accumulating during leaf expansion, or other bound forms of IAA initially stored in the cotyledons may be the substances hydrolysed. IAAsp appears to be accumulated during phases of low demand and to be exhausted during phases of high demand on IAA. Synthesis and hydrolysis of the conjugate may, therefore, influence the steady state concentration of the hormone during leaf develo

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02312.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The concentration of both nitrate and ammonium nitrogen was measured in soil taken from an upland acidic (pH 4.5) grassland habitat, containing four co‐existing species,Deschampsia flexuosa(L.) Trin.,Festuca ovinaL.,Juncus squarrosusL. andNardus strictaL. Both nitrate and ammonium nitrogen were found to be present in the soil, in similarly small quantities. The effect of both sources of nitrogen on relative growth rate was studied, and an attempt was made to determine whether nitrate or ammonium nitrogen is the immediate source of nitrogen for these plants using assays of nitrate reductase (EC 1.6.6.2) and ammonium uptake. All four species showed larger growth rates on the same concentration of ammonium nitrogen compared to nitrate nitrogen. All species showed low activities of leaf nitrate reductase, even in plants grown on 18 mol nitrate m−3. Ammonium uptake activity appeared to be higher in species which showed the lowest nitrate reductase activity and least response to increasing nitrate concentration in the growth med

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02313.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The characteristics of Cd2+accumulation byEuglena gracilisL. strain Z have been studied using sensitive and resistant cells. In both strains Cd2+is mainly absorbed by a temperature‐ and light‐dependent process. Resistance to Cd2+is associated with a lower accumulation of Cd2+and with a decreased affinity for Cd2+. Gel filtration on Sephadex G75 of the soluble fraction shows that resistance is not linked to an induction of metallothione

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02314.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The mitochondrial fraction isolated from plumular hooks of etiolated pea seedlings (Pisum sativumL. cv. Kelvedon Wonder) displayed a ten‐fold higher rate of ethylene formation from 1‐aminocyclopropane‐1‐carboxylic acid [ACC; 3.2 nmol C2H4(mg protein−1)h−1], than the tissue from which it was isolated. When the ionophores valinomycin or nigericin were added, a 60‐ to 70‐fold increase in activity in intact mitochondria over the activity in plumular hooks was obtained for ethylene formation under the same conditions, and a 20‐fold increase was obtained upon addition of gramicidin. The addition of ionophores did not affect the rate of ethylene formation in submitochondrial particles (55% inside‐out as determined by cytochrome oxidase latency) which already exhibited a 2–3‐fold higher specific activity than intact mitochondria. Low concentrations of the detergents cholate and deoxycholate increased mitochondrial ethylene formation activity and had no effect on the rate of the reaction in submitochondrial particles. These results support the suggestion that ACC conversion to ethylene is associated with the inner side of the inner mitochondrial membrane and that transport across the intact mitochondrial membrane is rate

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02315.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Developing grains of pearl millet (Pennisetum typhoidesBurm. S&H cv. PIB 155) were sampled and analyzed for starch and its free‐sugar precursors. The activities of invertase, sucrose‐ADP (UDP) glucosyl transferase and of α‐amylase and β‐amylase in relation to the rate of starch accumulation in the developing grain were assayed. By culturing detached ears, the incorporation of14C from free sugar precursors to starch was studied. The starch content gradually increased until grain maturity. The rate of starch accumulation was maximum around 12 days after anthesis. Around this period, the activities of sucrose‐ADP(UDP) glucosyl transferase and α‐amylase, β‐amylase were also at a peak. Invertase activity was high during the early period of grain development but gradually declined as the grains matured. In the most actively metabolising milky grains, incorporation of14C from [14C]‐sugars to starch was maximum in the mid mid‐milky grains. Addition of 20 mMK+to the culture solution did not affect the incorporation of14C from supplied sucrose to the free sugar pool and to the starch of the grain, but Mg2+supply at 20 mMconcentration lowered14C incorporation from exogenous sucrose to grain free sugars, although the utilization of the latter for starch s

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02316.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY