摘要:

Tobacco callus grown under shoot‐forming conditions or in the presence of gibberellic acid, which inhibits shoot formation, was incubated in [14C]‐sucrose at three different periods in culture and then replanted. Evolution of14CO2occurred during the 10 day post‐incubation period. Most of the radioactivity was incorporated into the ethanol‐soluble fraction, which lost most of its label after 24 h. Starch was the major ethanol‐insoluble component and post‐incubation synthesis occurred in this fraction for 24 h or longer. Greater net synthesis of starch occurred in shoot‐forming tissue and the loss of label from starch began later than in tissue cultured in the presence of gibbe‐rellic acid. Newly synthesized starch was not immediately utilised in the organogenic process, but its utilization could be correlated with the shoot

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01233.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Stomatal response, chlorophyll and carotenoid content, and photosynthetic electron transport were investigated inMedicago sativaL. (cv. Aragón) andTrifolium pratenseL. (cv. Violeta) after plants were exposed to various glyphosate [N‐(phophonomethyl)glycine] concentrations. The herbicide decreased the content of photosynthetic pigments when applied at concentrations of 0.15, 1.5 and 15 mM, showing a greater effect on chlorophyll pigments than on carotenoids. The chlorophylla/bratio increased as a consequence of a major effect on chlorophyllb.Glyphosate treatment (15 mM) led to a closure of stomates after seven days in both species. The results suggest that glyphosate acts as an electron transport inhibitor, because glyphosate pre‐incubated chloroplasts, isolated from control plants, showed reduced photosystem II and photosystem I activities. In general, clover was more sensitive to glyphosate than glyphosate, luc

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01234.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Sugar beets (Beta vulgarisL. cv. Monohill) grown in a complete nutrient solution, were treated with Cd2+(5 or 50 μM) and/or EDTA (10 or 100 μM) in different combinations. The Cd contents of five‐week‐old roots and shoots were determined by atomic absorption spectrophotometry, and the sucrose, glucose and fructose contents were measured enzymatically. The Cd2+uptake in both roots and shoots shows a linear relationship to the concentration of free Cd2+in the nutrient solution. This uptake is diminished in the presence of EDTA, suggesting that the Cd‐EDTA complex is unable to penetrate the membranes. The contents of glucose, fructose and sucrose in both roots and shoots decrease with increasing uptake of free Cd2+. This may be a secondary effect caused by the inhibition of photosynthesis in the presence of Cd2+. EDTA reduces the inhibition of Cd2+on sugar formation and accumulation. In the presence of EDTA alone the sugar content increases somewhat. EDTA slightly influences the dry weights of whole plants. The ratio roots:whole plants increases. Cd2+(≤ 50 μM) increases the dry matter portion of roots by ca 30%, but not that

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01235.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The effects of long‐term flooding on the growth of six‐month‐oldActinidia chinensisPlanch cv. Abbot plants and some effects on stomatal behaviour and leaf water relations were examined under controlled conditions for 28 days. Flooding caused stomatal closure and decreases in transpiration rate, xylem water potential, osmotic potential and turgor potential. Flooding also caused inhibition of the dry weight increase of leaves plus stems and of roots, chlorosis and necrosis of leaves, production of hypertrophied lenticels and the appearance of a small number of adventitious roots on the submerged portions of the stems. Rapid and partial stomatal closure by flooding may not only be due to the passive mechanical response which follows leaf dehydration, since flooded plants showed an increase in xylem water potential and osmotic potential during the first days of the experiment. The marked intolerance ofActinidia chinensisto flooding has been a serious barrier to its culture in poorly drained soils, hence careful irrigation management is req

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01236.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Protoplasts were prepared from cells of a tomato (Lycopersicon esculentumMill. cv. Lukullus) suspension culture and purified to eliminate the highly active exogenous RNase present in the enzyme mixture used for cell wall digestion. The purified protoplasts were used to determine the location of the endogenous RNase activity (measured at pH 5 with yeast RNA as the substrate). Vacuoles were released by shaking the purified protoplasts in alkaline buffer containing EDTA. RNase was unambiguously shown to be located within the vacuoles by (i) its co‐purification with the vacuoles in a discontinuous gradient and by (ii) the co‐migration of RNase and α‐mannosidase (EC 3.2.1.24), a vacuolar marker, during repeated centrifugation of the vacuoles. Vacuolar RNase was insensitive to EDTA, Mg2+, Mn2+and Ca2+but was stimulated by citrate or KH2PO4. It exhibited a pH‐optimum in the range of pH 5–6. Gel electrophoretic analysis revealed one single band for RNase of isolated vacuoles. This activity co‐migrated with an RNase from cells extracted under mild conditions. Thus, it was possible to distinguish the vacuolar RNase from the RNase of extracellular origin. RNA‐degrading activity was present in vacuoles throughout the growth of the culture. The activity in vacuoles gradually increased during exponential growth followed by a dramatic increase in the st

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01237.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

A factorial culture experiment was designed to investigate the influence of light regimes and of some metal chelators on the accumulation of cadmium byLemna gibbaL. The plants were grown in a complete nutrient solution containing Cd2+concentrations ranging from 0 to 27 μMwith or without EDTA, ethylenediamine‐N,N′‐bis‐(o‐hydroxyphenylacetic acid) (EDDHA) or salicylic acid. Each experiment was run for eight days in 18 h:6 h light:dark or continuous light. An increase in the Cd2+concentration in plants and a simultaneous drop in accumulation efficiency (ratio of Cd2+concentration in plants to the initial Cd2+concentration in the nutrient solution) with increasing ambient Cd2+levels was best represented by regression power curves. At the lowest Cd2+concentration which caused a significant decrease in the relative growth rate of duckweed, there was a decrease in manganese and zinc and an increase in the iron level in the plants. EDDHA and EDTA protected in some cases against the toxic action of cadmium without preventing its uptake by plants. It was thus observed that 9 μMor higher levels of Cd2+were toxic toLemna gibbadepending on the chelator and light regime. Duckweed grown in continuous light produced, in general, more dry matter and hence accumulated m

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01238.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Glassiness of willow (Salix babylonicaL.) can be controlled by the amount of ammoniacal nitrogen in the culture medium. In this study, glutamate dehydrogenase (EC 1.4.1.3) activity was observed in the different parts of the plant during induction of the vitrification process. The apparent affinity constants of the enzyme for ammonium were determined. The root enzyme displayed the highest affinity for ammonium (Km0.70 – 2.25 mM), and correlatively, its activity was linked to the amount of ammonium applied and to the development of the vitreous state. Although it has been shown that ethylene, matric potential and high cytokinin content are implicated in vitrification, the present study shows that a knowledge of the affinity constants for ammonium, when the ammoniacal nitrogen content of the culture medium is taken into account, can predict the risk of the plant material becoming vitreou

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01239.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Three different strains ofFrankia, the pure cultures AvcI1 and CpI1 and a local strain (crushed nodule inoculum), were compared in symbiosis with one clone ofAlnus incana(L.) Moench. Hydrogen metabolism, nitrogenase (EC 1.7.99.2) activity and relative efficiency of nitrogenase were studied as well as growth and nitrogen content of the plants. The localFrankiastrain showed no measurable hydrogen uptake but high H2‐evolution. No H2‐evolution was detected inFrankiaAvcI1 because of its hydrogenase activity. CpI1 also had hydrogenase, although only a very small H2‐evolution was detected at the end of the growth period. Hydrogenase activity was detected both in pure cultures and nodule homogenates of CpI1 and AvcI1. Growth, biomass production and nitrogen content were highest in alders inoculated withFrankiaAvcI1 while the lowest values were found for alders living in symbiosis with the localFrankiastrain. The presence of hydrogenase inFrankiaseemed to be benefical for growth and biomass production in the alders. However, the strains also differed with respect to spore formation. The local strain, but not AvcI1 and CpI1, formed spores in the root no

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01240.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Nigericin stimulated the ATPase activity of tightly‐sealed membrane vesicles prepared fromHevea brasiliensisMüll.‐Arg. lutoïds in the presence of K+. This stimulation required a functioning membrane since it was membrane‐bound and since it was not observed for the ATPase activity solubilized from the tonoplast by dichloromethane. The extent of nigericin‐induced stimulation of tonoplast ATPase was proportional to the ΔpH collapsed by the ionophore in the pres

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01241.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Net nitrate uptake,36ClO−3/NO−3influx and36Cl−influx intoPisum sativumL. cv. Feltham First seedlings have been examined following growth in culture medium containing different combinations of chloride and nitrate. When young (6 days old) seedlings, that had been grown in the absence of N were used, nitrate accumulation stimulated net nitrate uptake and36ClO−3/NO−3influx (r2= 0.99) while chloride accumulation inhibited nitrate uptake and36ClO−3/NO−3influx (r2= 0.65). When nitrate was provided during growth there was no effect of chloride pretreatment on net nitrate uptake and there was little effect of total [NO−3+ Cl−]ion36ClO−3/NO−3influx (r2= 0.26). A direct effect of Cl−on36ClO−3/NO−3influx was only found when seedlings had been starved of N for more prolonged periods (14 days).When moderate chloride was supplied during growth,36Cl−influx was insensitive to nitrate or chloride accumulated, but significantly correlated with loge[NO−3+ Cl−]i(r2= 0.75). When trace amounts of Cl−were supplied during growth36Cl−influx was inhibited by (a) NO−3in the external medium and (b) Cl−pretreatment, but was insensitive to NO−3pretreatment. The sensitivity of36Cl−influx to external nitrate was not found following Cl−pretreatment in the absence of nitrate. The possibility that there are two populations of chloride carriers which differ in their sensitivity to external nitrate is discussed. Tentative schematic models to account for the regulation of nitrate and chloride uptake are proposed in the context of current hypotheses for regulat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb01242.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY