摘要:

Changes in the activity and isoenzyme patterns of acid phosphatase, leucine aminopeptidase, glutamate-oxaloacetate transaminase, esterase, and malate and glutamate dehydrogenases were studied in cotyledon cell suspension cultures ofPhaseolus vulgarisgrown in the presence and absence of the growth regulators 2,4-dichlorophenoxyacetic acid and kinetin. With all enzymes studied, the pattern of isoenzymes and total enzymatic activity changed with the different phases of the culture cycle. In particular, the patterns of esterase, malate dehydrogenase, and glutamate dehydrogenase changed markedly with the inoculation of cells into fresh medium.The differences in isoenzyme patterns of cells grown with and without regulators were predominantly quantitative. However, certain minor isoenzymes of acid phosphatase, glutamate-oxaloacetate transaminase, esterase, and malate dehydrogenase were only detected in cultures grown in the presence of the regulators, while one isoenzyme of leucine aminopeptidase and two of esterase were unique to cells cultured in the absence of regulators.Three cathodic isoenzymes of acid phosphatase were released from wall material by 1 MNaCl. Such isoenzymes were also detected in the medium and in cytoplasmic extracts. Increase in the wall isoenzymes following inoculation into fresh medium was correlated with a decrease in anodic, cytoplasmic acid phosphatase.

ISSN:0008-4026    

DOI:10.1139/b78-262

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The phytotoxic actions of two herbicides, glyphosate and amitrole, were compared using corn seedlings. Six days after treatment with amitrole at 1.68 kg/ha, plant heights, leaf lengths, and shoot fresh weights were reduced 20, 20, and 25% respectively, whereas with glyphosate applied at 1.12 kg/ha the inhibition was 62, 60, and 84% respectively. The lowest concentration of glyphosate (0.28 kg/ha) inhibited plant growth more than the inhibition caused by the highest concentration of amitrole (3.36 kg/ha). A purple colour appeared on the whole shoot of plants treated with glyphosate, and with amitrole, only the new growth of shoots was white. Both treatments reduced chlorophyll levels and the amitrole treatment reduced the carotenoid levels more than the chlorophyll levels. The root growth of plants treated with 1.12 kg/ha glyphosate was inhibited more than 80%, whereas with amitrole at 1.68 kg/ha, the inhibition was 40%. Within 6 h glyphosate severely reduced the rate of root respiration and 12 h after treatment respiration was reduced more than 70%. This rapid effect on root respiration was not observed with amitrole, and even 48 h after treatment, the decrease in respiration was less than 30%. We conclude that the primary site of action of glyphosate in corn seedlings is in the roots whereas the effect of amitrole is in the shoot.

ISSN:0008-4026    

DOI:10.1139/b78-263

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Fusariumwas consistently isolated from leaf spots on English ivy (Hedera helixL.). ThisFusariumculture (mass culture) was single spored, and three distinct pigmentation types were evident: brown, red, and white. They appeared to be cultural variants of the mycelial type and were identified asFusarium tricinctum(Corda) Sacc. Perithecia resulting from pairings of certain combinations of these single-spored cultures, or from the mass culture, were formed on water agar containing cold-sterilized dried stem pieces of coastal Bermuda hay (Cynodon dactylonPers.).Gibberella tricinctan.sp. is proposed for the binomial of the heterothallic sexual state, which is heretofore undescribed. In vitro inoculation of detached English ivy leaves with ascospores or conidia of the pathogen reproduced the leaf spotting originally observed; however, pathogenicity was very limited under the conditions studied.

ISSN:0008-4026    

DOI:10.1139/b78-264

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

A period of 1 to 3 days imbibition followed by drying altered the subsequent germination responses of seeds ofRumex crispusL. When the imbibition took place under alternating light and temperature conditions subsequent germination was faster and more complete. In contrast, when the seeds imbibed at a constant temperature and in nearly continuous darkness subsequent germination was delayed and less complete. Subsidiary tests demonstrated that (a) within a 24-h drying period, the seeds lost virtually all water imbibed over 1 to 3 days; (b) a 3-day imbibition pretreatment was followed by faster, more complete germination in a 0.25 M mannitol solution; (c) the duration of the drying period (up to 29 days) had little effect on the outcome; and (d) seeds pretreated for 1 to 3 days under an alternating light and tempèrature regime germinated more rapidly than untreated seeds when sown in soil in a greenhouse. These results help to explain why seedlings ofR. crispasappear rapidly each summer following a drought-ending downpour, whereas seeds of the same species buried deep in the soil acquire a secondary dormancy and may remain viable for up to 80 years.

ISSN:0008-4026    

DOI:10.1139/b78-265

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Excised root samples from 901 plants, representing 130 species of nonnodulated angiosperms largely in upland, pioneering habitats, were assayed for nitrogenase activity by the acetylene-reduction technique after overnight preincubation of the samples under lowpO2. Most samples and most species exhibited very low excised root acetylene-reducing activities, but for 19 species, maximum values were greater than 50 nmol C2H4∙g−1∙h−1. In situ C2H2assays, conducted on 10 species which had exhibited maximum excised root activities greater than 10 nmol C2H4∙g−1∙h−1, indicated average belowground N2-fixation rates of 3 to 92 g N∙ha−1∙day−1and maxima greater than 100 g N∙ha−1∙day−1for 3 of the 10 species. The highest values were for grasses characteristic of poorly drained soils and for some dicotyledonous weeds. It is concluded that the potential of temperate-zone angiosperms for nitrogenase activity by 'associative symbioses' approaches that of tropical

ISSN:0008-4026    

DOI:10.1139/b78-266

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Experiments are reported which demonstrate the interaction of temperature with genotype in controlling germination in wild oats. In some pure lines germination of newly matured seeds occurs at all temperatures in the range 4–32 °C. Other pure lines exhibit strong suppression of germination in the midportion of this temperature range. The possible adaptive significance of this dimorphism in nature is discussed.

ISSN:0008-4026    

DOI:10.1139/b78-267

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The isoflavonoid phytoalexin medicarpin has been found to accumulate in leaflets of high- and low-coumarin cultivars ofMelilotus albaandMelilotus officinalisfollowing inoculation with the fungusHelminthosporium carbonum. Little or no medicarpin was isolated from leaflets treated with deionised water. Medicarpin was also produced when leaflets were irradiated with short-wavelength ultraviolet light. Elimination of the high-coumarin character from sweet clover cultivars does not appear to affect phytoalexin production, and in consequence, low-coumarin varieties should not be more susceptible to fungal colonisation than their high-coumarin counterparts.

ISSN:0008-4026    

DOI:10.1139/b78-268

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The fine structure of actively growing hyphae ofColletotrichum graminicolawas investigated. The hyphae were found to secrete a mucilaginous sheath into which melanizing particles and fibrils were deposited. Classical ubiquitous mitochondria, multipored doublewalled nuclei, ribosomes, mesosome-like structures, lomosomes, vacuoles, and inclusions such as lipids, closely associated with vacuoles, especially noticeable during germination, as well as glycogen were present. During maturation, vacuoles appeared and enlarged. In addition, a few endoplasmic reticulum profiles were observed in actively growing hyphae. Mitochondrial profiles changed from spherical to elongate. A plasmalemma, perhaps double in nature, was present. Penetration of one hypha by another was also observed.The mature appressorium exhibited a thick three-layered cell wall. This thick wall appeared to play a part in poor fixation and embedding, resulting in a poor definition of such cellular organelles as ribosomes, nuclei, etc. Internally, appressoria, depending on the stage of development, exhibited many vacuoles and osmiophilic deposits indicative of lipid reserve material. A germ pore through which a germ tube and migrating organelles and cytoplasm emerged was also observed.

ISSN:0008-4026    

DOI:10.1139/b78-269

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Gliocladium catenulatumparasitizesSclerotinia sclerotiorumandFusariumspp. It kills the host by direct hyphal contact causing the affected cells to collapse or disintegrate. Pseudoappressoria are formed by the hyperparasite but hyphae derived from them do not penetrate the host cell walls. Vegetative hyphae of all species tested and macroconidia ofFusariumspp. are susceptible to this hyperparasite but chlamydospores ofFusarium equisetiare resistant.

ISSN:0008-4026    

DOI:10.1139/b78-270

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Phytoalexin production and browning were elicited in Dark Red Kidney bean cotyledons by application of mycelial walls isolated from three races ofColletotrichum lindemuthianum. Two races, α and δ, were avirulent on this bean cultivar and a third, β, was virulent. Heat treatment of aqueous suspensions of the α, (β, and δ mycelial walls released soluble polysaccharides that elicited browning and phytoalexin production on bean cotyledons. These polysaccharides were not adsorbed by anion or cation exchange resins and ranged in size up to at least a molecular weight of 106. The highest molecular weight fractions were predominantly glucans and showed elicitor activity on cotyledons with application of less than 10−6 g glucose equivalents. The soluble polysaccharide extracts also possessed minor amounts of sugars which differed among the α, β, and δ races.

ISSN:0008-4026    

DOI:10.1139/b78-271

出版商:NRC Research Press    

年代:1978

数据来源: NRC