摘要:

AbstractThe physiological basis for senescence symptoms induced by spraying attached primary leaves of bean plant (Phaseolus vulgarisL. cv. Brittlewax) with silicone oil emulsions was investigated. It was found that chlorophyll levels declined significantly between 24 and 48 h after spraying, whereas neither protein levels nor respiration rates were affected over a 7‐day period. Rates of photosynthesis and reducing sugar levels in silicone‐sprayed leaves were however significantly reduced after 1 and 24 h respectively. These responses were obtained using plants grown under low stress controlled environment conditions. By contrast, leaves on greenhouse plants did not senesce in response to silicone sprays. A possible mechanism of silicone oil action based on selective leaf penetration and inhibition of photosynthesis is postula

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01539.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractWheat seeds (Triticum aestivumL. cvs. Yorkstar and Sirius) were cut transversely into embryoless and embryo‐containing (embryonated) halves and the content of endogenous cytokinins and gibberellins in both halves determined before and after the seeds imbibed water for 12–15 h at 22°C in the light. Dry seeds contained little ethyl acetate‐extractable gibberellin activity as measured by bioassay butn‐butanol‐soluble cytokinins were detected mainly in the embryoless halves. Dry, embryonated half‐seeds contained water‐soluble gibberellins which could be extracted into acidic ethyl acetate after treatment of the aqueous extract with either alkaline phosphatase, β‐glucosidase or a crude pectolytic enzyme preparation.When half‐seeds were allowed to imbibe water for 12 h and then extracted, cytokinin activity was largely lost from the embryoless halves and completely from the embryonated halves and water‐soluble gibberellins were also lost from the embryonated halves. However, ethyl acetate‐soluble gibberellins were present in the latter suggesting that “bound’ gibberellins were released during imbibition. The hormones present in normal and naturally embryoless dry grains of cv. Yorkstar were also determined. Both gibberellin and cytokinin activity was higher in normal grains suggesting that the presence of an embryo is essential for synthesis or accumulation of these hormones in t

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01540.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractBoth acid and alkaline invertases were present in immature juice sacs of satsuma mandarin (Citrus‘Unshu Marcovitch”) fruit, in which sugar content was low. Maturing and mature juice sacs, in which sugar content increased steadily with time, were characterized by the presence of alkaline invertase and the absence of acid invertase.When the immature juice sacs were homogenized with 0.2Msodium phosphate‐citrate buffer (pH 8.0), almost all of the acid invertase activity was found in the solubilized fraction, whereas almost all of the alkaline invertase activity was present in the insoluble fraction. The distribution of alkaline invertase between the solubilized and insoluble fractions changed with the development of fruit.The acid invertase had a molecular weight of 69,000, optimum pH of 4.8–5.3, andKmvalue for sucrose of 7.3 mM.The alkaline invertase had a molecular weight of 200,000, pH optimum of 7.2–7.7, andKmvalue of 35.7 mM.The hydrolysing activities of both enzymes for raffinose were considerably less than those for sucrose. The alkaline invertase had lower activity for raffinose than the acid

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01541.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe differentiation stage of the caulonema inFunaria hygrometricaprotonema is distinguished from the chloronema stage by three additional protein bands (CSP) in the soluble protein fraction. During the change of caulonema to chloronema, which is induced by isolation of single filaments (regeneration), the CSP disappear. This is not the consequence of an accelerated degradation or turnover but of a gradual termination in thede novosynthesis of CSP during regeneration as demonstrated by pulse‐chase experiments withl‐[4,5–3H] leucine. Cytokinin inhibits the termination of the synthesis of CSP. The decrease in synthesis parallels the decrease in ability of the isolated caulonema cells to respond to cytokinin via bud formation. It is therefore concluded that the CSP are involved in the competence of caulonema cells to respond to cytok

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01542.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractBased upon the method we developed to measure ethylene in very low concentrations (as low as 0.01 ppb in the ambient atmosphere) an experimental chamber was constructed and integrated in the measuring system for plant physiological studies. Parameters influencing the accuracy of the technique are evaluated. The pressure in the plant chamber increased 0.05 atm at a flow rate of 10 1/h during ethylene trapping. At this flow rate the ethylene production per seedling is independent of the number of seedlings used. The ethylene measured per seedling is directly proportional to the length of trapping time. Under standard conditions of chamber configuration and volume very small changes in ethylene content can be detected accurately in a very short time range. Our experimental arrangement allows kinetic studies of ethylene evolution by biological objects in a qualitative and quantitative manner. All methods used heretofore are more complicated and less accurate compared to the measuring system presented here. Its versatility is demonstrated for bothin vitroandin vivostudies of ethylene production by bean seedlings. The application fields of the apparatus are discussed.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01543.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractHomogenates of tomato (Lycopersicon esculentumMill.) tissues oxidize IAA at a rate proportional to their peroxidase activity. Moreover, isoproteins with peroxidase activity catalyze also the oxidation of IAA. Two monogenic recessive mutations,olivaceaandmonstrosa, are involved in the control of the peroxidase‐IAA oxidase activity. Inolivacealeaflets this activity is 15 times that of the normal; all the aerial organs ofmonstrosashow high activities, particularly the midrib. These high activities depend on the enhancement of the organ‐specific isoenzymes and on the derepression of the root isoenzyme band C2. This latter peroxidase‐IAA oxidase band is present inolivaceaandmonstrosaleaflets, inmonstrosastems and, less intensely stained, inmonstrosamidribs. The reduction in length and weight of mutant organs and their epinastic and geotropic‐like behavior are associated with high peroxidase‐IAA oxidase activities and with the derepression of the root‐specific band C2. These results suggest an important role of the peroxidase‐IAA oxidase system in controlling the metric relationships among different organs of the plant.Olivaceaandmonstrosaare to be viewed as auxin‐related mutations controlling the synthesis of a group of proteins rela

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01544.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractFive cereals and two related grasses were tested for adventitious shoot production from tissue cultures using methods concordant with those reported to be successful for cereals. The five cereals I wheat (Triticum aestivumL.), oats (Avena sativaL.), and maize (Zea maysL.) Pioneer hybrid 3369A, the Bolivian race Pororo and the Equadorian race Chococenõl were all found to proliferate in culture through an aberrant root‐like mechanism of growth which had the external appearance of callus. Two related species, teosinte (Zea mexicanaReeves and Mangelsdorf) and tripsacum (Tripsacum dactyloidesL.), were less successful in culture, but grew in the same way. Oats, and probably Pororo and Chococeño, initiated presumptive shoot meristems directly from root vascular tissues within this root‐like growth. Hybrid maize and wheat initiated no shoot meristems and produced only roots. The occasional shoot production observed in wheat was discounted as simple carryover of existing shoot apices from the primary embryo cultures. This study suggests that the incidence of shoot regeneration in cultures of these cereals may be related more directly to adventitious bud formation on roots than to any controlledde novoorganogenesis from undifferentiated c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01545.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe photosynthetic capabilities of the fernPteris creticavar.ouvrardiiwere analysed by means of the light response curves of CO2exchange. In control growth conditions (greenhouse, low‐light: 20–32 W m−2); photosynthesis was shown to be saturated for low irradiance (20–25 W m−2); the saturating photosynthetic rate, very low as compared to higher plants, was due to an extremely high intracellular resistance. When irradiance during the photosynthesis measurement was higher than 60–80 W m−2, a constant decline of net CO2exchange as a function of time was observed.When irradiance during growth was enhanced, whether in greenhouse (20–250 W m−2) or controlled (62 W m−2) conditions, the first fronds that had developed in the new condition from the crosier stage exhibited decreased net maximal photosynthesis and a decreased efficiency in low light, but saturating irradiance was unmodified. However, the fronds whose entire differentiation (from meristem) occurred under these moderate irradiances (plants defoliated of all fronds and crosiers at the time of transfer), possessed more efficient photosynthetic characteristics than control plants.Pterisis able to grow under extreme shade conditions (4–8 W m−2); light saturating photosynthesis and efficiency are higher under extreme shade than under control conditions. These adaptive characteristics indicate thatPterisis a wel

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01546.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe effect of phosphorus and potassium deficiencies on transpiration in tea (Camellia sinensisL. Clone DT 1) was studied. The plants were grown in sand culture, and measurements were made after the plants showed phosphorus or potassium deficiency symptoms. The overall growth of plants was reduced by potassium deficiency but not by phosphorus deficiency. Both deficiencies reduced stomatal aperture and increased leaf water potential. Stomatal density decreased in phosphorus deficient leaves and it increased in potassium deficient leaves. The transpiration of whole plants was reduced by both deficiencies. The relative sensitivity of transpiration to water stress was increased by potassium deficiency but not by phosphorus deficiency.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01547.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractSeeds of winter wheat (Triticum vulgareL.) cultivars Fema and Ferto, were vernalized at 3°C in the dark. Samples were taken 9, 18, 27, 36 and 45 days after the start of vernalization, and extracts were analysed for auxins, gibberellins and growth inhibiting substances. As vernalization progressed the levels of auxins and gibberellins increased whereas the levels of growth inhibitors decreased. The pattern of growth regulator changes was almost similar in both the cultivars. Vernalization seemingly controls the balance between growth promoting and growth inhibiting substances in winter wheat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1978.tb01548.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY