摘要:

SUMMARYAt its northernmost distributional limit in northeastern America, in Newfoundland,Bryopsis hypnoidesLamour. appears to have a heteromorphic, monophasic life‐history. Zygotes resulting from fusion of anisogametes develop in culture into prostrate filamentous germlings, these also reproducing sexually by anisogametes to form a new generation of the prostrate type. ErectBryopsislater grew from the prostrate phase: asexual stephanokontic zooids were entirely absent. The life‐history in Newfoundland compares in part with that forB. hypnoidesfrom northern parts of its European range; the presence of sexual reproduction in the prostrate phase in Newfoundland, however, is unique inBryopsisand is not apparently a temperature dependent phenomenon. In the field NewfoundlandB. hypnoidesreaches sexual maturity in winter at temperatures less than 0°C. Germling phases studied in culture could not be located in the field. The question is raised as to the possible genetic isolation of NewfoundlandB. hypnoidesfrom populations in Eu

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00898.x

年代:1973

数据来源: WILEY

摘要:

SUMMARYGolgi vesicles from the tips of growing pollen tubes ofPetuniawere isolated on a discontinuous sucrose gradient and compared with those in vivo by means of EM techniques. The results indicate that the isolation procedure does not alter the morphology of the Golgi vesicles. The isolation technique developed renders it possible to analyse biochemically the contents of Golgi vesicles in relation to cell wall synthesis in germinating pollen.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00899.x

年代:1973

数据来源: WILEY

摘要:

SUMMARYA procedure for in vitro culture of floral buds of petunia is described. A relatively simple medium, agar + sucrose, supports the normal development of premeiotic cultured buds in vitro. Meiosis in vitro proceeds similarly to in vivo under different (from 20°C to 40°C) temperature regimes. Compared with other species the duration of meiosis is relatively short (12 hours from zygotene to tetrads

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00900.x

年代:1973

数据来源: WILEY

摘要:

SUMMARYHistological studies of bean rust colonization revealed that mesophyll colonization accelerates abruptly on the sixth day following inoculation corresponding to (a) the time of development of the first visible symptoms and (b) the often reported manifold increase in respiration of diseased leaves. There is an accompanying hypertrophy of mesophyll cells. These observations are considered as further evidence that much of the respiratory increase may be ascribed to the fungus but they do not discount host contributions.With scanning electron micrography and standard histological techniques, new observations made on the early stages of pustule development cast doubt on the (assumed) role of tactile pressure in uredial opening.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00901.x

年代:1973

数据来源: WILEY

摘要:

SUMMARYThe action spectrum for the phototropical curvature of the coremia ofP. isariiformewas determined by means of unilateral illumination. The I50(Λ), that is the light intensity at wavelength Λ at which 50% of the coremia react positively, was calculated from a series of experiments with the help of the probit analysis. The I50(Λ), the 95% confidence interval, and the relative quantum efficiency were calculated and a plot of the values gave the action spectrum. This spectrum is quite different from the action spectra for sporulation and initiation of coremia in the same fungus. However, with peaks at 425 nm, 450 nm and 476 nm, it resembles rather well the action spectra for other light‐sensitive fungi. Therefore it might be assumed that inP. isariiformethe same photoreceptor as in other fungi is active. The great difference between the three action spectra remains to be explained. Possibly a screening pigment causes the distortion of the action spe

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00902.x

年代:1973

数据来源: WILEY

摘要:

SUMMARYDuring flower development in tobacco (Nicotiana alataLink&Otto) changes in peroxidase activity in the unpollinated style and in the corolla were determined both qualitatively and quantitatively. In both the peroxidase activity increases during maturation, especially towards the end of the growth period. Immediately after anthesis the peroxidase activity in the style decreases during two days, followed by a strong increase. The changes in peroxidase activity in the style are different from those in the corolla.The alterations of isoenzyme patterns during flower development are primarily quantitative rather than qualitative. Only one new isoenzyme appears during the growth in style and corolla.The possible relationship between the variations in peroxidase activity in the style and the physiological barrier preventing self‐fertilization is discusse

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00903.x

年代:1973

数据来源: WILEY

摘要:

SUMMARYTreatment of dark‐grown gherkin seedlings with dichlobenil (2,6‐dichlorobenzonitrile) causes an increase in the phenylalanine ammonia‐lyase (PAL) activity in the hypocotyl. This is explained by the following mechanism. Hydroxycinnamic acids, end products of the pathway in which PAL is a key enzyme, are normally mainly present in cell compartments separated from compartments containing phenol oxidizing enzymes such as peroxidases and phenol oxidases. Dichlobenil increases the permeability of membranes for hydroxycinnamic acids, making these acids available for the oxidizing enzymes. This results in the deposition of lignin‐like material and in the decrease in the concentration of soluble hydroxycinnamic acids. In its turn this leads to derepression of PAL synthesis and/or diminished inactivation of PAL resulting in a higher PA

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00904.x

年代:1973

数据来源: WILEY

摘要:

SUMMARYChanges in fresh and dry weight, total nitrogen, protein nitrogen, phosphorus, potassium, and sulphur, have been followed in the shoot and in the root of young pea seedlings grown under a variety of growth conditions. It is shown that light inhibited shoot elongation, transport of reserve materials from the cotyledons, and acropetal transport, but enhanced net protein synthesis both in the shoot and in the root, and accumulation of mineral elements in the root. Treatment of the seedlings with gibberellic acid (GA) partly lifted the growth inhibition caused by light and shifted the nitrogen metabolism close to that of dark‐grown seedlings, but did not affect transport from the cotyledons and only slightly the internal distribution of minerals.Competition between the shoot and the root from light‐grown seedlings for the reserve minerals studied is not established until the end of the second week. The extent of secondary transport depends on the element considered. Potassium appears to be highly immobile once deposited, under the conditions of these experiments, while sulphur is the most mobile, nitrogen and phosphorus behaving in an intermediate way. Although the amount of acropetal transport depends on the growth conditions and age of the seedlings, the influence of these variables is non‐specific, as indicated by the constant proportion in which the different elements are transported to the

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00905.x

年代:1973

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00906.x

年代:1973

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1973.tb00907.x

年代:1973

数据来源: WILEY