摘要:

The contribution of cytochrome and alternative pathways to respiration during soybean [Glycine max(L.) Merr. cv. Chippewa 64] seed formation and maturation was measured by oxygen consumption of embryonic axis and cotyledon tissues and of mitochondria isolated from immature seeds. Respiration rates (dry weight basis) declined duing the last month of seed maturation. Cyanide sensitive respiration (cytochrome pathway) accounted for 80 to 90% of total oxygen consumption throughout seed formation and maturation. The proportion of the total respiration resistant to 1 mMcyanide and inhibited by 1 mMsalicylhydroxamic acid (alternative pathway) did not exceed 6%. A residual oxygen consumption, accounting for 5 to 15% of total respiration, persisted in the presence of both inhibitors. Likewise, virtually no alternative respiration was found in mitochondria prepared from immature seeds. The alternative respiratory pathway seems absent during soybean seed formation and maturation regardless of whether grown in the greenhouse or field.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02758.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Sown on water, seeds ofKalanchoëbiossfetdianaPoelln. cv. Feuerblute are absolutely light‐requiring and show full red/far‐red reversibility. In seeds, sown on 2 ×10‐3M gibberellic acid, red/far‐red reversibility disappears and both short red and far‐red irradiations induce germination. Gibberellic acid alone does not induce germination, but it increases the physiological activity of Pfrto the extent, that the low Pfrlevel obtained by far‐red irradiation becomes very effective. The synergism between gibberellic acid and far‐red light appears after a two‐day incubation; period. The nature of this lag phase was examined by measuring both germination and uptake of labelled gibberellic acid in intact seeds and seeds with a punctured seed coat. The lag phase was shown to be independent of the uptake kinetics of gibberellic acid and allows development to a specific stage, necessary for germination after phytochrome‐phototransformation. The kinetics of the uptake of gibberellic acid by intact seeds and embryos of intact seeds are different. In intact seeds most of the gibberellic acid is retained in the seed coat; only a small fraction actually penetrates to the embryo where it can exert its phy

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02759.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Diffusates from the hypocotyl and leaves of sunflower seedlings (Helianthus annuusL. cv. Mammoth) contain both auxin and inhibitor(s) of auxin‐induced growth. The auxin activity has been evaluated with the conventionalAvenacoleoptile bioassay employing negative curvature, The inhibitor activity has been determined with a newly developed bioassay, measuring the positive curvature response of theAvenacoleoptile. This bioassay has been standardized by the response to 2,3,5‐triiodo‐benzoic acid. Diffusates from plants in darkness have higher auxin activity and lower inhibitor activity than diffusates from plants in light. Irradiation at 730 nm promotes auxin synthesis in leaves, and! irradiation at 660 nm promotes synthesis of the inhi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02760.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Nitrate reductase (NADH: nitrate oxidoreductase, EC 1.6.6.1) of spinach (Spinacia oleraceaL.) leaves, inactivated in vitro by acetylene, was reactivated by irradiation with blue light. Red + infrared, green or white light of the same irradiance were less effective. The dehydrogenase activity of the nitrate reductase complex was not required for pliotoreactivation. Photoreactivation of cyanide‐inactivated nitrate reductase was greatly enhanced by the addition of 1 and 20μof either FMN or FAD; however, flavins showed a much smaller stimulatory effect on photoreactivation of acetylene‐inactivated enzyme. The effect of flavins was higher under anaerobic conditions. This might imply the direct ievolvement of excited flavins in the photoreactivation mechanism. Besides promoting photoreactivation, blue light irradiation led simultaneously to a gradual inactivation of the enzyme especially under air and 20μFMN, eventually abolishing the recovered activity of the e

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02761.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Wheat seedlings (Truicum aestivumL. cv. Starke II, Weibull) grown in a solution of the herbicide SAN 9789 axe deficient in chlorophyll and carotenoids. Such seedlings were used in order to isolate a blue light response of stomata, not mediated by photosynthesis. When illuminated with blue light (430‐505 nm) SAN‐grown seedlings showed a considerable transpiration response, whereas red light (>590 nm) gave no response whatsoever with the intensities used. The transpiration was measured with hygrometers in an open air‐flow system. Furthermore, blue light had a superior effect, relative to red, in causing a transpiration response in untreated green seedlings. The transpiration level after two hours of illumination was higher in blue than in red light, although the blue light had its major effect immediately after the light was switched on. The difference between the effects of blue and red light was most pronounced at low light intensities. This, together with the high sensitivity of SAN‐grown seedlings to low ntensity blue light, led to the conclusion that blue light is of special importance at low quantum fluxes. Because of the very low carotenoid content in the SAN‐grown seedlings, the role of the carotenoids as photoreceptors for the blue light response of stomata was

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02762.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In isolated broken chloroplasts photosynthetic electron transport requires the presence of CO2and/or bicarbonate. This bicarbonate effect on electron flow was measured in a medium containing 100 mMsodium formate. In this medium a dark incubation time with bicarbonate is required for the reactivation of the Hill reaction. We have measured the kinetics of the reactivation of electron flow by varying the dark incubation of CO2‐depIeted pea (Pisum sativumL., cv. Rondo) chloroplasts with bicarbonate. The half‐time of this reactivation appears to be 25 s when 2 mMbicarbonate is added.The dinitrophenol herbicide,i‐dinoseb, is shown to be a competitive inhibitor of the bicarbonate dependent Hill reaction with an inhibitor constant (Ki) of 31 nM. In the presence of 100 nMi‐dinoseb or 100 nMDCMU the half‐time of the reactivation by 2 mMbicarbonate appears to increase to about 58 s. We provide an explanation for these phenomena by analyzing the bicarbonate‐thylakoid interaction on the basis of a simple reaction scheme. The binding of bicarbonate to the thylakoids appears to be a second order reaction with pseudo‐first order kinetics. According to our analysis, any inhibitor, which is competitive with respect to the bicarbonate stimulation of the Hill reaction, should increase the half‐time of the reactivation of th

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02763.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Uptake and distribution of Ca+, Mg2+and K2+were investigated in plants of cucumber (Cucumis sativusL. var. Cila) which had been cultivated for 12, 19, 32, or 53 days in complete nutrient solution with 1.0 mMCa2+, 2.0 mMMg2+and 2.0 mMK+. The+concentration was about the same in roots and shoots, while the Ca2+and Mg2+concentrations were low in roots compared to shoots. The K+concentration decreased with increasing leaf age, while the Ca2+and Mg2+concentrations increased, except in older plants with flowers and fruits, where an increased concentration was found in the youngest leaves. This is discussed in connection with increased indoleacetic acid (IAA) synthesis in the shoot. Excision of leaves at different levels from 21‐day‐old plants, followed by uptake for 24 h from the nutrient solution on days 22 and 23, resulted in no immediate reduction in Ca2+(45Ca) uptake. Transport of Ca2+increased to leaves above and below the excision point and total Ca2+uptake remained at the same level as for the intact plant. It is suggested that regulation of Ca2+uptake is primarily achieved in the root while the distribution in the shoot is regulated by the accessability of negative binding si

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02764.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

N‐phenyl indoryl‐3‐butyramide (NP‐IBA) and phenyl indole‐3‐thiolobutyrate (P‐ITB) are new synthetic auxins that enhance rooting of bean (Phaseolus vulgariscv. Top Crop) hypocotyl cuttings and jack pine (Pinus banksianaLamb.) seedling cuttings. In comparison with an equal concentration of indole‐3‐butyric acid (IBA), NP‐IBA treatment resulted in greater rooting of bean and jack pine seedling cuttings. IBA and P‐ITB treatment at equal concentration were equally effective in inducing rooting of bean cuttings. However, in comparison with an equal concentration of IBA, P‐ITB treatment promoted greater rooting of jack pine seedling cuttings, but P‐ITB treatment was less effective than NP‐IBA treatment. Application of crystalline chemical to jack pine seedling cuttings indicated lesser toxic effects and earlier and greater root‐promoting effects of P‐ITB and NP‐IBA treatments, in comparison with IBA treatment. The earlier rooting of NP‐IBA‐treated jack pine seedling cuttings was positively related to increase in fresh weight of basal 1 cm stem before primordia were initiated. Weight of basal steins of NP‐IBA‐treated cuttings initially increased during propagation at day 2 in comparison with the control, and at day 3 in comparison with IBA‐treated cuttings. Results that were obtained with seedling jack pine cuttings were generally c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02765.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A three‐phase partitioning method to separate indolyl‐3‐acetic acid (IAA) and abscisic acid (ABA) from a crude plant extract was developed and evaluated. The aqueous phase at pH 2.7 of a methanolic plant extract constituted the 1st phase, from which IAA and ABA were transferred via diethyl ether, the 2nd phase, to a 3rd phase consisting of an alkaline buffer, enclosed in a dialysis tube. Partitioning of the free forms of the two hormones among the three phases in one container were carried out simultaneously and efficiently. The method also proved to be satisfactory when used as a combined step for both extraction and partitioning, at which the plant homogenate in buffer at pH 2.7 constituted the 1st phase. The content of IAA and ABA in kernels ofZea maysand in hypocotyls ofBeta vulgariswere tested with the new method. The method presented is reliable and time‐saving, and the demand for chemicals is less than for most of the conventional procedur

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02766.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In the garden pea (Pisum sativumL.), shoots of the extremely short plants with the mutant na (phenotype nana) are found by bioassay to contain undetectable levels of gibberellin‐like substances. This is confirmed by the use of near isogenic lines differing at theNalocus. Thus, mutantnaappears to block a step early in the pathway of gibberellin synthesis. It is suggested that the polar gibberellin‐like substance found in the apical portion of shoots of tall (Le) but not dwarf (le) peas could be GA1. Extracts of shoots ofna Lepeas treated with GA20(the major active gibberellin in dwarf peas) possess a large amount of GA1‐like activity whereas extracts of shoots ofna lepeas treated with GA20possess a much reduced amount. Thus, geneLemay allow the conversion of a less active gibberellin (GA20) into one more active in stimulating elongation in the pea (the GA1‐like compound). In contrast to their influence in the shoot, thenaandLegenes do not appear to be operative in controlling the gibberellin content of developing seed, indicating that organ specific gibberellin biosynthesis and metabolism occur

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb02767.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY