摘要:

Terry, P. H., Krizek, D. T. and Mirecki, R. M. 1988. Genotypic variation in coleus in the ability to accumulate abscisic acid in response to water deficit. ‐ Physiol. Plant. 72: 441–449.Abscisic acid (ABA) concentration and plant and soil water potentials were determined in leaves of three cultivars ofColeus blumeiBenth. cvs. Marty, Buckley Supreme and PI354190, chosen for their differences in sensitivity to drought, SO2and/or chilling stress. Plants were subjected to ‘gradual’ soil moisture stress (SMS) for 0–6 days, during which time the soil dried out slowly and to more ‘rapid’ SMS for 0–9 days where the soil dried out at a faster rate. Plants were propagated from clonal stock in the greenhouse and transferred to the growth chamber, where they were maintained for 1 week prior to beginning water stress treatment. ABA concentration was determined as the methyl ester using a gas chromatography ‐ electron capture detector method. Samples for ABA determinations were taken from the third pair of leaves from the apex at the same time each day (1430 h). Measurements of stomatal conductance (C5) and leaf water potential (φl) were made on the fourth pair of leaves from the apex, using the same plants as those sampled for ABA. During the more rapid stress portion of the study soil matric potentials (φm) were monitored on a daily basis. Despite large cultivar differences in ABA concentration at 0–6 days, by 7–9 days these differences had largely disappeared. Except for drought‐insensitive cv. Marty, there was generally little correlation between ABA levels and measurements of plant and soil

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09149.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Ingestad, T. and Ågren, G. I. 1988. Nutrient uptake and allocation at steady‐state nutrition. ‐ Physiol. Plant. 72: 450–459.Net nutrient uptake and translocation rates are discussed for conditions of steady‐state nutrition and growth. Under these conditions, the relative uptake rate is equal to the relative growth rate, for whole plants as well as for plant parts, since the root/shoot ratio and internal concentrations remain stable. The nutrient productivity and the minimum internal concentration are parameters characteristic for the plant and the nutrient. A conceptual, mathematical model, based on these two fundamental parameters is used for calculation and prediction of the net nutrient uptake rate, which is required to maintain steady‐state nutrition at a specified internal nutrient concentration or relative growth rate. When uptake rate is expressed on the basis of the root growth rate, there is, up to optimum, a strong linear relationship between uptake rate and the internal concentration of the limiting nutrient. More complicated and less consistent relationships are obtained when uptake rate is related to root biomass.The limiting factor for suboptimum uptake is the amount of nutrients becoming available at the root surface. When replenishment is efficient, e.g. with vigorous stirring, the concentration requirement at the root surface appears to be extremely low, even at optimum. In the suboptimum range of nutrition, the effect of nutrient status on root growth rate is a critical factor with a strong feed‐back on nutrition, growth and allocation. At supraoptimum conditions, the uptake mechanism is interpreted as a protection against too high uptake rates and internal concentrations at high external concentration.In birch (Betula pendulaRoth.), the allocation of nitrogen to the shoots is high compared to that of potassium and also to that of phosphorus at low nitrogen or phosphorus status. With decreasing stress, phosphorus allocation becomes more and more similar to nitrogen allocation. The formulation of a mathematical model for calculation of allocation of biomass and nutrients requires more exact information on the quantitative dependence of the growth‐regulating processe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09150.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Mengel, K. and Geurtzen, G. 1988. Relationship between iron chlorosis and alkalinity inZea mays. ‐ Physiol. Plant. 72: 460–465.Maize (Zea mays L.cv. Anjou 21) grown in nutrient solution with Fe‐EDTA and with nitrate as the sole nitrogen source showed typical Fe‐chlorosis symptoms after a growth period of 14–21 days. Alkalinity in roots, stems and leaves of the chlorotic plants was high. Transferring the chlorotic plants from the nitrate‐containing nutrient solution to a solution of (NH4)2SO4resulted in a regreening of leaves within 2–3 days which was associated with a decrease in solution pH, a decrease in alkalinity of plant parts, a translocation of Fe from roots to tops and a release of Fe into the outer solution. Similar effects were obtained when Fe chlorotic plants were transferred to a dilute HO solution with pH 3.5.Spraying chlorotic leaves with indoleacetic acid or with fusicoccin led also to a regreening of leaves without having a major effect on leaf alkalinity.Interpretation of the experimental results is based on the assumption that nitrate as sole N source leads to a high pH level in the apoplast resulting in the precipitation of Fe compounds, probably Fe oxide hydrate. Ammonium nutrition has the reverse effect since it lowers the apoplast pH and this can result in the dissolution of Fe compounds. Application of indoleacetic acid as well as fusicoccin supposedly stimulates the proton pumps in the plasmalemma of the leaf tissue. The resulting decrease in apoplast leaf pH in the microenvironment also leads to a dissolution of Fe compounds in the apoplast and thus promotes the uptake of Fe by

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09151.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Hasenstein, K. H. and Evans, M. L. 1988. The influence of calcium and pH on growth in primary roots ofZea mays.‐ Physiol. Plant. 72: 466–470.We investigated the interaction of Ca2+and pH on root elongation inZea maysL. cv. B73 × Missouri 17 and cv. Merit. Seedlings were raised to contain high levels of Ca2+(HC, imbibed and raised in 10 mMCaCl2) or low levels of Ca2+(LC, imbibed and raised in distilled water). In HC roots, lowering the pH (5 mMMES/Tris) from 6.5 to 4.5 resulted in strong, long‐lasting growth promotion. Surprisingly, increasing the pH from 6.5 to 8.5 also resulted in strong growth promotion. In LC roots acidification of the medium (pH 6.5 to 4.5) resulted in transient growth stimulation followed by a gradual decline in the growth rate toward zero. Exposure of LC roots to high pH (pH shift from 6.5 to 8.5) also promoted growth. Addition of EGTA resulted in strong growth promotion in both LC and HC roots. The ability of EGTA to stimulate growth appeared not to be related to H+release from EGTA upon Ca2+chelation since, 1) LC roots showed a strong and prolonged response to EGTA, but only a transient response to acid pH, and 2) promotion of growth by EGTA was observed in strongly buffered solutions. We also examined the pH dependence of the release of45Ca2+from roots of 3‐day‐old seedlings grown from grains imbibed in45Ca2+. Release of45Ca2+from the root into agar blocks placed on the root surface was greater the more acidic the pH of the blocks. The results indicate that Ca2+may be necessary for the acid growth respons

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09152.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Biondi, S., Torrigiani, P., Sansovini, A. and Bagni, N. 1988. Inhibition of polyamine biosynthesis by dicyclohexylamine in cultured cotyledons ofPinus radiata.‐ Physiol. Plant. 72: 471–476.The effect of 1 mAf dicyclohexylamine (DCHA) on the synthesis of spermidine and spermine was examined in excised cotyledons of radiata pine (Pinus radiataD. Don) cultured under shoot‐forming (with cytokinin) and non‐shoot‐forming (minus cytokinin) conditions by incubation with [14C]‐putrescine. In control cotyledons incorporation into spermidine showed a peak at day 2 in the presence and at day 5 in the absence of N6‐benzyldenine (BA). DCHA‐treated cotyledons gave the same labeling pattern, both in the presence and absence of benzyladenine, with a much smaller peak at day 2. The incorporation into spermidine and spermine was insignificant at day 5 and later. The total radioactivity in the trichloroacetic acid supernatant indicated that precursor uptake was strongly reduced by the drug. In addition, the percentage label found in the benzene phase and combined in the 3 polyamines was lower in DCHA‐treated cotyledons. Thus, treatment with DCHA not only inhibited the conversion from putrescine to spermidine and spermine, but also reduced its conversion to other benzene‐extractable compounds. S‐Adenosylmethionine decarboxylase (SAMDC, EC 4.1.1.50) activity, which furnishes the propylamine group to spermidine and spermine synthases (EC 2.5.1.16 and EC 2.5.1.‐), was not significantly affected by DCHA and appeared to be independent of the spermidine and spermine synthase reactions, suggesting that spermine synthesis decreased as a result of substrate depletion. The correlation between morphological development and polyamine bi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09153.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Adkins, S. W., Symons, S. J. and Simpson, G. M. 1988. The physiological basis of seed dormancy inAvena fatua. VIII. Action of malonic acid ‐ Physiol. Plant, 72: 477–482.A low concentration of malonic acid (50 mM) induced germination in four genetically pure dormant lines ofAvena fatuaL. Sensitivity to this treatment was poor immediately after harvest but increased markedly during after‐ripening, indicating that the mode of action of malonic acid (50 mM) was similar to that of another organic acid, citric acid. Over the concentration range (10–50 mM) where malonic acid promoted germination, oxygen uptake was also stimulated, and this was before the first visible signs of germination. At higher concentrations (100–300 mM) where there was no promotion of germination, malonic acid strongly inhibited oxygen uptake. These results show that malonic acid has a dual effect on oxygen uptake and subsequent germination. Low concentrations (10–50 mM) act by stimulating the Krebs cycle and germination through an acidification reaction like citric acid, and high concentrations (100–300 mM) act by inhibiting germination through enzymatic restraint of the Krebs cycle.The stimulation of both oxygen uptake and germination by three established germination promoters (sodium nitrate, citric acid and ethanol) was inhibited by a high concentration of malonic acid (200 mM) but unaffected by a low concentration (50 mM). These results show that oxygen uptake, and hence the activity of the Krebs cycle, are important processes involved in the dormancy breaking mechanism of these th

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09154.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

van der Werf, A., Kooijman, A., Welschen, R. and Lambers, H. 1988. Respiratory energy costs for the maintenance of biomass, for growth and for ion uptake in roots ofCarex diandraandCarex acutiformis. ‐ Physiol. Plant. 72: 483–491.The respiratory characteristics of the roots ofCarex diandraSchrank andCarex acutiformisEhrh. were investigated. The aims were, firstly to determine the respiratory energy costs for the maintenance of root biomass, for root growth and for ion uptake, and secondly to explain the higher rate of root respiration and ATP production inC. diandra.The three respiratory energy components were derived from a multiple regression analysis, using the relative growth rate and the net rate of nitrate uptake as independent variables and the rate of ATP production as a dependent variable. Although the rate of root respiration and ATP production was significantly higher inC. diandrathan inC. acutiformis, the two species showed no significant difference in their rate of ATP production for the maintenance of biomass, in the respiratory energy coefficient for growth (the amount of ATP production per unit of biomass produced) and the respiratory energy coefficient for ion uptake (amount of ATP production per unit of ions absorbed). It is concluded that the higher rate of root respiration ofC. diandrais caused by a higher rate of nitrate uptake. At relatively high rates of growth and nitrate uptake, the contribution of the rate of ATP production for ion uptake to the total rate of ATP production amounted to 38 and 25% forC. diandraand C.acutiformis, respectively. At this growth rate, the respiratory energy production for growth contributed 37 and 50%, respectively, to the total rate of ATP production. The relative contribution of the rate of ATP production for the maintenance of biomass increased from 25 to 70% with increasing plant age for both species. The results suggest that ion uptake is one of the major sinks for respiratory energy in roots.These experimentally derived values for the rate of ATP production for the maintenance of biomass, the respiratory energy coefficient for growth and the respiratory energy coefficient for ion uptake are discussed in relation to other experimentally and theoretically derived val

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09155.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Kobek, K., Focke, M., Lichtenthaler, H.K., Retzlaff, G. and Würzer, B. 1988. Inhibiton of fatty acid biosynthesis in isolated chloroplasts by cycloxydim and other cyclohexane‐1,3‐diones. ‐ Physiol. Plant. 72: 492–498.The effect of the three cyclohexane‐1,3‐dione herbicides cycloxydim, sethoxydim and clethodim (proposed common name) on the de novo fatty acid biosynthesis of isolated chloroplasts as test system was investigated with intact chloroplasts isolated from sensitive grasses (Poaceae) and tolerant dicotyledonous plants. All three herbicides blocked the de novo fatty acid biosynthesis ([14C]‐acetatc incorporation into total fatty acid fraction) inAvena sativaL. cv. Flämingnova chloroplasts in a dose‐dependent manner. The I50‐values are lower for cycloxydim and clethodim than for sethoxydim. The rate of de novo fatty acid biosynthesis in isolated, intact and photosynthetically activeAvenachloroplasts was higher in the light than in the dark, which appeared to be due to the light‐dependent regeneration of the cofactors ATP and NADPH. The de novo fatty acid biosynthesis by isolated chloroplasts from the tolerant dicotyledonous species pea (Pisum savivumL. cv. Kleine Rheinländerin), spinach (Spinacea oleraceaL. cv. Matador) and tobacco (Nicotiana tabacumL. cv. su/su) was insensitive to the three herbicides. It is assumed that one of the enzymes of the fatty acid biosynthesis is modified in the dicotyledonous plants and not accessible to the cyclohexane‐1,3‐dione herbicides. In the case ofPoa annuaL., which as a whole plant is tolerant towards sethoxydim, the tolerance seems not to lie in the chloroplasts but in properties of the cytoplasm, since the isolated chloroplasts are

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09156.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Branca, C, De Lorenzo, G. and Cervone, F. 1988. Competitive inhibition of the auxin‐induced elongation by α‐D‐oligogalacturonides in pea stem segments. ‐ Physiol. Plant. 72: 499–504.α‐D‐galacturonide oligomers (OG) were prepared by partial hydrolysis of sodium polypectate with an homogeneousAspergillus nigerendopolygalacturonase (EC 3.2.1.15). OG, obtained after digestion for 10, 20, 30, 60, 120 min and 24 h, were assayed for their ability to interfere with the IAA‐induced elongation of pea (Pisum sativum L.cv. Alaska) stems. Maximum inhibiting activity was exhibited by oligomers with an approximate degree of polymerization higher than 8. Inhibition by longer OG was much lower, and the products of the 24 h digestion and the unhydrolysed polypectate were ineffective. The addition of OG to pea stems caused a parallel shift to the right of the IAA dose‐effect curve. The shift depended on the amount of OG used, showing that oligogalacturonides behave as competitive antagonists of IAA. The presence of OG caused the disappearance of the second maximum of the elongation rate and reduced the first maximum. OG were also tested for their ability to inhibit IAA‐induced ethylene evolution of pea stem segments. Maximal inhibition was obtained with OG of the same size as those that interfered with IAA‐induced elongation. Inhibition of the auxin action seemed to be specific as OG did not interfere with the activity of gibberellic acid (GA3) or kinetin. It was concluded that oligogalacturonides strongly interfere with the activity of IAA, although they are by themselves incapable to influence the elongation of pea

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09157.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Jarl, C. I., Ljungberg, U. K. and Bornman, C. H. 1988. Correction of chlorophyll‐defective male‐sterile winter oilseed rape (Brassica napus) through organelle exchange: Characterization of the chlorophyll deficiency. ‐ Physiol. Plant. 72: 505–510.As is known, the introduction of male‐sterileRaphanus sativusL. cytoplasm intoBrassica napusL. results in male‐sterile oilseed rape plants, which display a temperature‐related chlorophyll defect. The influences of temperature and irradiance on this defect were investigated. Compared to a line of normal (green phenotype) male‐fertile oilseed rape, the male‐sterile line had reduced chlorophyll content, fewer chloroplasts per cell, an altered ultrastructure of the chloroplasts and reduced activities of both photosystems, although the relative amounts of the photosystems and the chlorophylla/bratio were similar. The lower activity of the photosystems is explained by a decreased functional antennae size and a reduced efficiency in the interactions between the nuclear‐encoded light‐harvesting proteins and the reaction centres coded for by the plastome. Some thylakoid polypeptides differed in proportion between the male‐fertile line with green phenotype and the male‐sterile line with chlorotic phenotype. Characters, in which the two lines exhibited differences, are ascribed to difficulties in molecular communication between the oilseed rape nucleus and the radish cytoplasm, which are combined in the de

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb09158.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY