摘要:

Pea (Pisum sativumL.) cv. Afghanistan inoculated withRhizobium leguminosarumbiovar.viciaeaborts the nodulation process if North American strains are used but will form effective nodules with strain TOM. Early nodulins (nodule specific root proteins) were examined byin vitrotranslation of total root or root + nodule RNA and two-dimensional gel analysis. Qualitatively different protein patterns were found between effective nodulation in Trapper (a North American variety) and 'Afghanistan' and between effective and abortive nodulation in 'Afghanistan'. Six days after inoculation a 26-kDa protein was evident that was only produced in Trapper roots and several nodulins were visible. Nodulin N-37 was present in effective and abortive combinations. Nodulin N-52 was present in inoculated Trapper but not in inoculated 'Afghanistan', whereas N-23 was present in inoculated 'Afghanistan' but not in inoculated Trapper. Nodulin N-58 occurred only in abortive combinations with 'Afghanistan'. Nonnodulating Trapper (Trapper into which the nonnodulation genes of 'Afghanistan' had been back-crossed) showed the same patterns of gene expression as 'Afghanistan'. The expression of several genes apparently differs between 'Afghanistan' and Trapper for the nodulation process.

ISSN:0008-4026    

DOI:10.1139/b89-327

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Lodgepole pine (Pinus contortaDougl.) germination, as indicated by radicle emergence from the seed coat, was completed 2 days after imbibition at 28 °C. By this time, the hydrolysis of the megagametophyte storage protein reserve had commenced. This was 90% complete 5 days after imbibition. Megagametophytes and embryonic axes contained two classes of peptidases: aminopeptidases that hydrolyzed amino acid β-naphthylamides, and carboxypeptidases. Cell-free extract studies showed that carboxypeptidase activity was very low in mature seed megagametophytes and embryonic axes, but increased rapidly in these tissues after radicle emergence. However, maximum rates of carboxypeptidase activity only occurred when 70% of the megagametophyte storage protein reserve had been depleted 5 days after imbibition. Thus, it was unlikely that carboxypeptidases played a significant role in the rapid mobilization of megagametophyte storage proteins. Mature seed megagametophytes contained high levels of aminopeptidase activity. Following germination this level of activity was maintained in megagametophytes and only declined when storage protein hydrolysis was almost completed, 5 days after imbibition. It is proposed that aminopeptidases are involved in the hydrolysis of megagametophyte storage proteins in the germinated lodgepole pine seed.

ISSN:0008-4026    

DOI:10.1139/b89-328

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Insoluble crystalloid proteins formed the major storage reserve in the mature lodgepole (Pinus contortaDougl.) seed where they were found mainly in the megagametophyte. Smaller amounts were identified in the embryonic axis. These proteins had a subunit molecular mass in the presence of sodium dodecylsulphate of 50–55 kDa. Crystalloid subunits were heterodimers with subunit polypeptide molecular masses of 33–36 and 22–23.5 kDa. Following the emergence of the radicle from the seed coat, this reserve was rapidly mobilized in both the megagametophyte and the embryonic axis, and clearly played a major nutritional role in the germinated seed. In the megagametophyte, crystalloid protein hydrolysis appeared to involve the production of a buffer-soluble protein with a molecular mass of 34 kDa that was a heterodimer. Several soluble megagametophyte and embryonic axis proteins were identified that were also rapidly hydrolyzed following germination. These too could play a storage role. Crystalloid protein hydrolysis in the megagametophyte was not accompanied by a significant increase in the soluble megagametophyte amino acid pool. In contrast, the soluble amino acid pool of the embryonic axis increased markedly following germination. Isolated germinated embryonic axes did not show this increase. Thus, amino acids generated by crystalloid protein hydrolysis appeared to be immediately exported to the developing embryonic axis, presumably to support the many metabolic events that are occurring during its early growth.

ISSN:0008-4026    

DOI:10.1139/b89-329

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Based on field studies in New Brunswick and Ontario, two species of the genusPyxidiophoraare demonstrated to be of frequent occurrence.Pyxidiophorasp. andPyxidiophora spinuliformishave complex life cycles involving anamorph formation and sporulation on a phoretic mite host.Pyxidiophorasp., the more common of the two species, appears to be parasitic on the apothecia of coprophilous Pezizales where it forms clusters of synnemata within a week of dung deposition. Later, perithecia develop among the synnemata and produce ascospores. Ascospores attach to mites that are, in turn, carried by beetles and flies to a new substrate. On the new substrate while attached to the mite, ascospores ofPyxidiophorasp. differentiate into linearly arranged or complex and often muriformThaxteriolathalli, which produce phialoconidia. The phialoconidia appear to be the propagules that inoculate the new substrate.Pyxidiophora spinuliformishas a life cycle similar to that ofPyxidiophorasp. but differs in having a conidial anamorph with a different development and ascospores that never form muriform thalli on the phoretic mite host. The taxonomic, ecological, and evolutionary significance of these findings is discussed.

ISSN:0008-4026    

DOI:10.1139/b89-330

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Differences in flowering phenology may be an important premating reproductive barrier between willow species. The seven sympatric species studied fall into two flowering groups within which there is substantial seasonal overlap: an early flowering group that includesSalix bebbianaSarg.,Salix discolorMuhl.,Salix eriocephalaMichx., andSalix petiolarisSmith, and a later flowering group that includesSalix amygdaloidesAnderss.,Salix exiguaNutt., andSalix lucidaMuhl. The species flowering sequence was reasonably consistent over the 3-year period from 1984 to 1986. Thermal control over flowering phenology was related to cumulative growing degree-days. The inheritance of phenological responses in artificially produced F1interspecific hybrids was intermediate between that of the parental species.

ISSN:0008-4026    

DOI:10.1139/b89-331

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Tests were conducted with cuttings of bean (Phaseolus vulgarisL. cv. Top Crop) and jack pine (Pinus banksianaLamb.) seedlings to determine the influences of the new auxins 4-carbomethoxyvinylenephenyl indole-3-butyrate (CMVP-IBA) and 2,4-dichlorophenyl indole-3-butyrate (DCP-IBA) on adventitious rooting. For comparison, bean cuttings were used to determine the effects on adventitious rooting of the unsubstituted phenyl ester of IBA, phenyl indole-3-butyrate (P-IBA). Results indicated that, compared with IBA, treatment with CMVP-IBA resulted in less adventitious rooting of jack pine and bean cuttings, treatment with DCP-IBA resulted in equal adventitious rooting of jack pine and bean cuttings, and treatment with P-IBA resulted in greater rooting of bean cuttings (jack pine was not tested). Based on results of the present and previous research, the phenyl esters of indole auxins have equal or greater root-inducing activity, compared with the parent auxin, only if their phenolic moieties do not contain a substituent (e.g., P-IBA) or contain only a simple substituent such as -OH (e.g., 3-hydroxyphenyl indole-3-acetate) or -Cl (e.g., DCP-IBA), rather than a more complex substituent like -CH=CH—COOCH3(e.g., CMVP-IBA). However, further research is needed to test the accuracy of these generalizations.

ISSN:0008-4026    

DOI:10.1139/b89-332

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Wall development during primary spore formation, discharge, and germination of Entomophthorales is emphasized in ultrastructural studies ofConidiobolus,Entomophaga,Neozygites, andErynia. In the fungi examined, spore and sporophore walls consist of a thick, electron-translucent inner layer and a thin, electron-dense outer layer. During spore formation, cytoplasm of the supporting sporophore cell migrates into the spore initial. As the former cell empties, a septum develops. Discharge is caused by inversion of the papillum, which lacks the electron-dense layer. Only inEryniadid the two spore wall layers separate upon impact. Intracytoplasmic organization of the primary spore is typical of the Zygomycotina; the morphology of organelles was characteristic of species, whereas nuclear ultrastructure was consistent within genera.Conidiobolusnuclei have a prominent nucleolus that lacks heterochromatin, in contrast with the other genera where large patches of heterochromatin were observed. Upon germination, no rupture of the spore outer layer was observed other than at points of germ tube emergence. The germ tube wall was continuous with the inner spore wall layer. The results are discussed in reference to Entomophthorales taxonomy and definition of the terms conidium and monosporous sporangiolum.

ISSN:0008-4026    

DOI:10.1139/b89-333

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

We have examined the long-standing hypothesis that leaves are morphologically more complex following prolonged proximity to the shoot apical meristem. Growth rates of the petiole and rachis of conventional and mutant pea leaves were compared for successive nodes of insertion in seedling plants. Leaves were longer at higher nodes, though the relative growth rate did not vary. Mature afila leaves were longer than those of conventional and tendril-less genotypes. The afila leaf alone exhibited a transient, highly significant rise in relative growth rate during the plastochron interval P4.5–P5.5. This rise occurred after the stage at which leaves of the different genotypes were anatomically distinguishable (stage P2–P3). Rates of vertical displacement of the leaf primordium from the shoot apical meristem did not differ significantly among genotypes. Our data suggest that the rate of leaf extension is one of the consequences, rather than a cause, of leaf morphology.

ISSN:0008-4026    

DOI:10.1139/b89-334

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The fungusBotrytis cinereaPersoon (ex Fries) is an important pathogen of container-grown conifer seedlings. The examination of whole mounts and serial sections of diseased needles of western larch (Larix occidentalisNuttall) seedlings with a light microscope confirmed that the development of fungal infection structures conforms to that observed in nonconiferous hosts. Both stomatal and cuticular penetrations were evident. Infection hyphae displayed occasional taxis toward stomata on senescent needles but not on healthy needles. The treatment of seedlings with fungicides at levels corresponding to 1 and 10% normal application rates induced no consistent changes in fungal structures.

ISSN:0008-4026    

DOI:10.1139/b89-335

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Isozyme variation of 291 isolates ofAtkinsonella hypoxylon(Clavicipitaceae, tribe Balansieae) from 24 populations of its four known host grasses (Danthonia compressa,Danthonia sericea,Danthonia spicata, andStipa leucotricha) was examined using starch gel electrophoresis. In total, there were 20 distinct multilocus genotypes. Eleven out of 13 enzyme loci (84.6%) exhibited more than one allele (mean 2.8) per locus. Nei's total gene diversity (HT) within all isolates was 0.229. Between isolate samples fromS.leucotrichaand the threeDanthoniahosts, Nei's genetic identity (I) ranged from 0.21 to 0.31 and among isolate samples from the threeDanthoniaspeciesIranged from 0.65 to 0.88, with isolates fromD.spicataandD.compressabeing most similar. Variation ofA.hypoxylonoccurred both within and among populations ofD.spicataandD.compressa, where up to 53 isolates were sampled per host population. In contrast, all 20 isolates fromS.leucotrichawere identical, as were all 6 fromD.sericea. A few isolates fromD.spicataexhibited the same, unusual multilocus genotype with unique alleles at six different loci. The occurrence of several multilocus genotypes in isolates from the same ascostroma and the 1:1 segregation of genotypes among ascospores from a single ascus indicated gene exchange among sexually reproducing individuals, consistent with a heterothallic mating system forA.hypoxylon.

ISSN:0008-4026    

DOI:10.1139/b89-336

出版商:NRC Research Press    

年代:1989

数据来源: NRC