摘要:

Bush bean (Phaseolus vulgarisL. cv. Tenderette) plants were grown in north‐south (N‐S) and east‐west (E‐W) rows under field conditions to test effects of row orientation on reflected far‐red (FR) light patterns and on shoot size and edible bean productivity. Soil water and nutrients were adequate. Plants in N‐S rows received slightly higher ratios of FR relative to red (R) light, because of heliotropic movement of the leaves. Plants in N‐S rows partitioned more dry matter to shoots and edible green beans than those in E‐W rows. We conclude that row orientation of broadleaf plants can affect the FR/R light ratio and the phytochrome‐mediated regulation of plant development under

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb01996.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Six lines of sorghum (Sorghum bicolorL. Moench) with differing drought resistance (IS 22380, ICSV 213, IS 13441 and SPH 263, resistant and IS 12739 and IS 12744, susceptible) were grown under field conditions in the semi‐arid tropics and analysed for proline and nitrate reductase activity (NRA; EC 1.6.6.1) during a mid‐season drought. The resistant lines accumulated high levels of proline, while the susceptible lines showed no significant proline accumulation. Most of the proline was accumulated after growth of the plants had ceased. In a separate greenhouse experiment, most of the proline was found in the green rather than the fired portions of leaves. The levels returned to that of irrigated controls within 5 days of rewatering. Proline levels increased as leaf water potential and relative water content fell, and there was no apparent difference among the different sorghum lines with change in plant water status. Susceptible lines accumulated less proline than resistant lines as leaf death occurred at higher water potentials. Proline accumulation may, however, contribute to the immediate recovery of plants from drought. Leaf NRA reached high levels at about 35 days after sowing in both the stressed and irrigated plants, after which it declined. The decline in NRA was more pronounced in the stressed than in the irrigated plants and closely followed changes in the growth rate. Upon rewatering, NRA increased several‐fold in all the lines and, in contrast to proline accumulation, genotypic differences in NRA were small, both during stress and upon rewatering. The high sensitivity of NRA to mild drought stress was reflected in the rapid decline of activity with small changes in leaf water potential and relative water content. The results are discussed in the light of a possible role for proline during recovery from drought, and the maintenance of NRA during stress and its recovery upon rewat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb01997.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Polyamine oxidase (PAO, EC 1.5.3.3) activity and polyamine content in the cell wall and soluble fractions obtained from embryos, endosperms and shoots and roots of etiolated or green seedlings of maize (Zea maysL. cv. WF9) during the first 7 days of germination were investigated. Polyamine content was also determined in the trichloroacetic acid‐soluble (free polyamines) and trichloroacetic acid insoluble (bound polyamines) fraction obtained from the same tissues. PAO activity, determined by the radiometric method based on the recovery of the labelled reaction product 1‐pyrroline, was mostly localized in the cell wall fraction. The activity was very low in embryos and endosperms and present in traces in roots. In etiolated shoots PAO activity increased sharply, while in green shoots it was low and increased slowly. No polyamines were found in the cell wall fraction and only putrescine was detected in the soluble fraction, with the exception of the embryo, where spermidine and spermine were also present. In the TCA‐soluble fraction of embryos, putrescine increased during imbibition, while spermidine and spermine decreased; in the endosperm no relevant changes in polyamines occurred. In the same fraction of green and etiolated seedlings, putrescine increased, giving a peak at days 3–5, while spermidine decreased to very low levels. The amount of bound polyamines was 1–4% of the free ones. The pattern of PAO activity seems to be unrelated to endogenous free polyamine content, which is the same in shoots and roots of etiolated and green seedlings. Enzyme activity, very low in ungerminated seeds, increased continuously during the progression of germination, especially in etiolated shoots, indicating a possible involvement in cell wall

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb01998.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The isolation and characterization of anl‐aspartate aminotransferase (AAT) activity (EC 2.6.1.1) in the unicellular green algaChlamydomonas reinhardtii6145c are reported for the first time. The enzyme transaminates aspartate with the 2‐oxoglutarate‐glutamate system, and exhibits maximum aminotransferase activity at pH 7.8 and 37°C. It has an Mr of 138 kDa, contains pyridoxal 5′‐phosphate, and has a Kmapparent for oxalacetate of 0.55 mMand exhibits positive co‐operativity withl‐aspartate with an S0.5of 2.53 mMand a Hill coefficient of 1.57. In vivo, activity levels were affected by the carbon and nitrogen sources and by the change in the dark‐light conditions. All these responses are interpreted in terms of a possible physiological regulation of AAT activity to keep the intracellular pools of glutamate and aspartate within margins compatible with environmen

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb01999.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Experiments designed to study the effect of light quality and quantity and their possible interaction with benzyladenine (BA) in the control of in vitro proliferation ofPrunus insititiaSchneider GF 655–2 microcuttings are reported. The action of BA as a promoting factor of shoot formation was expressed only in the presence of light. The concentration response curves for BA‐induced proliferation were very similar under the different light sources, irrespective of proliferation rate values.Shoot formation under blue, far‐red and white light was enhanced by the highest photon fluence rates, while the efficiency of red seemed to be independent of this factor. The results suggest the action of a low‐energy response in the red waveband and under the low photon fluence rates of blue and white. The inhibition of shoot elongation induced by BA in the dark as well as under all light treatments indicates that, while the BA‐induced release from the apical dominance is light dependent. BA inhibition of shoot elongation is entirely light in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb02000.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Anaerobic production of succinate, a common feature in animals able to sustain anoxia, has seldom been reported in plants. By the use of1H‐nuclear magnetic resonance spectroscopy we show here that succinate is produced by rice seedlings(Oryza sativaL. cv. Arborio) subjected to anoxic conditions. Starting from levels below I μmol (g fresh weight)−1in air, after 48 h of anoxia the levels of alanine, succinate and lactate had increased to 23.8, 5.2 and 1.0 μmol (g fresh weight)−1, respectively, in shoot tissues. Succinate was accumulated in shoots, notably in the coleoptiles, but not in roots of the rice seedlings, suggesting its involvement in rice coleoptile elongation under anoxia. Other possible functions of succinate production in rice seedling, an organism highly tolerant to anoxia, are di

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb02001.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Analysis of published data for the most widely used bioassays for cytokinins reveals that the dose responses are usually subsensitive, i.e. that S90/S10>81. The data are. in general, insufficiently detailed and/or precise for the kinetics (cooperative, multiphasic or more complex) of the subsensitive responses to be determined. Genus‐and species‐specific differences in response type were found for callus growth, where the responses are ultrasensitive (S90/S10<81) for tabacco andPhaseolus Iunatusbut mostly subsensitive for soybean andP. vulga

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb02002.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The possible involvement of auxin in the action of gibberellin in stimulating cell elongation was examined by comparing the effects of gibberellic acid (GA) and IAA on the growth, osmoregulation and cell wall properties of the Alaska pea (Pisum sativumL. cv. Alaska) subhook. Both GA and IAA stimulated cell elongation in the subhook region of derooted cuttings. Cotyledon excision decreased the stimulating effect of GA on the growth of the subhook region, but did not affect that of IAA. As the subhook region elongated, the osmotic potential of the cell sap and the total amount of osmotic solutes increased. Cotyledon excision accelerated the increase in the osmotic potential and suppressed the accumulation of osmotic solutes. In cuttings with cotyledons. GA partly counteracted the increase in the osmotic potential and substantially promoted the accumulation of osmotic solutes. On the other hand, in cuttings without cotyledons. GA did not affect the change in the osmotic potential although it slightly promoted the accumulation of osmotic solutes. IAA accelerated the increase in the osmotic potential, but did not affect the accumulation of osmotic solutes. IAA enhanced the extensibility of the cell wall, while GA did not affect it. These results suggest that at least in the Alaksa pea subhook region. GA does not stimulate cell elongation by affecting the level of auxin.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb02003.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Populus euramericana(Dode) Guinier cv. Robusta plants were cultivated at irradiances of 7.5, 15 and 30 W m−2(32.5, 65 and 130 μmol m2s−1), 400–700 nm at 22°C and a relative humidity between 40 and 60% on a gravel culture subirrigated with Hoagland's nutrient solution. The basal diameter of the growing shoot, a measure of the number of apical cells participating in growth, increased proportionally to irradiance and was correlated with mature leaf length. The development of the length of the growing shoot (Lgs) depended also on the nutritional status of the (young) shoot. Lgswas strongly correlated with the rate of height

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb02004.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Mechanical perturbation (MP, gentle tubbing) promoted the senescence of detached oat (Avena sativaL. cv. Victory) leaf segments in the dark. The promotion of senescence increased with increase in the number of rubbings and could be seen after 24 h of dark incubation; the maximum effect was reached on day 3. The effect (% of control) of MP on the loss of protein was greater than the effect on chlorophyll (Chl) loss on day 1. However, on day 3 the effect of MP on the loss of Chl became greater than the effect on the loss of protein. Ethephon and 1‐aminocyclopropane‐1‐carboxylic acid (ACC) marginally promoted the loss of Chl by both control and rubbed oat leaf segments, and the effect was additive with MP. Chloramphenicol (CAP), spermine, aminoethoxyvinylglycine (AVG) and Ca2+marginally delayed the loss of Chl and protein in both control and rubbed segments. Kinetin greatly retarded the senescence of all segments. Even in the presence of these substances, the amounts of Chl and protein in the rubbed segments were always less than in their respective controls, thus retaining the effect of the MP. However, abscisic acid (ABA) and cycloheximide (CHI) caused the rubbed oat leaf segments to retain more Chl and protein than their respective control segments. The effect of CHI was actually enhanced by MP. Rubbing promoted the senescence of attached leaves of oats (Avena sativaL. cv. Victory), maize (Zea maysL. cv. Early Belle) and pumpkin (Cucurbita pepoL. cv. Jack‐o‐lantern) cotyledons in the dark. Rubbing promoted the senescence of oat leaf segments even in light, although to a lesser extent compared to the effect in the dark. The senescence of leaves of pumpkin and cocklebur (Xanthium strumariumWallr. var.Pennsylvanicum) in situ was also enhan

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb02005.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY