摘要:

A continuous range of variation in vegetative proliferation among members of the red fescue complex is documented in (ii) the number of spikelets proliferating in the inflorescence, (ii) the position where initiation of proliferation occurs, (iii) the rachilla, where abnormal elongation may result in internodes 3–10 mm long, and (iv) the position of proliferation, which may be either lateral or terminal on the rachilla. Both facultative and obligatory vegetative proliferation occur. Recorded chromosome counts of 2n = 49, 50, 63, and 70; low pollen stainability; absence of seed; and occurrence of proliferation in spikelets of known hybrids suggest that at least some specimens are the products of hybridization. In North America, the nameFestuca proliferahas been applied to vegetatively proliferating specimens ofF.richardsonii,F.rubras.l,, and some specimens that may be hybrids. Although proliferating spikelets are conspicuous, they do not justify taxonomic rank.

ISSN:0008-4026    

DOI:10.1139/b88-001

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Comparisons of differences between morphological means of individual plant parts indicate that the greatest source of variation in two populations ofBalsamorhiza sagittatais the individual plants within populations; within-population diversity is greater than among-population diversity. Variable covariance and correlations differ between individual plants and there are subgroups of interrelated variables that can be tied to developmental phenomena. The relationship between developmental phenomena and these groups of variables suggests a relationship between organizational, as reflected in variable interrelationships, and ontogenetic variation. These results are not adequately explained by neoDarwinian theory but are explained more comprehensively by a theory of evolution that views biological change over time as an intrinsically driven self-organization, accompanied by an increase in complexity (a manifestation of the "Second Law of Thermodynamics" as it applies to open systems).

ISSN:0008-4026    

DOI:10.1139/b88-002

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Phenylalanine ammonia-lyase activity increased rapidly beginning 2 h after inoculation withPhytophthora megasperma(Drechs.) f.sp.glycinea(Hildeb.) Kuan & Erwin race 1 in unwounded hypocotyls of soybean cv. Harosoy 63 (resistant) but did not change significantly in cv. Harosoy (susceptible). Small increases in phenylalanine ammonia-lyase activity also were caused by wounding. Activity increased more slowly in hypocotyls (cv. Harosoy 63) wounded just before inoculation than in intact inoculated hypocotyls, but most activity developed in hypocotyls wounded 12 h before inoculation. There were comparable effects of wounding on symptom development. Trifoliolate leaves of 14-day-old cv. Harosoy 63 plants are resistant, but trifoliolate leaves of 12-day-old cv. Harosoy 63 plants and of 14-day-old cv. Harosoy plants are susceptible to race 1. Increases in phenylalanine ammonia-lyase activity following inoculation were demonstrated only in 14-day-old Harosoy 63 plants but not until 24–36 h after the inoculation. Significant accumulation of glyceollin occurred by 24 h. Susceptible trifoliolate leaves of 12-day-old cv. Harosoy 63 plants produced only low levels of glyceollin following either infection or treatment with the abiotic elicitor AgNO3, whereas trifoliolate leaves of 14-day-old cv. Harosoy plants produced high levels of glyceollin in response to AgNO3. It is concluded that trifoliolate leaves of 12-day-old, as opposed to 14-day-old, cv. Harosoy 63 plants have not developed mechanisms that trigger responses to either infection or the abiotic elicitor or they are deficient in metabolic processes that support glyceollin biosynthesis or other defense-related responses.

ISSN:0008-4026    

DOI:10.1139/b88-003

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

TheArnica angustifoliaaggregate is a circumpolar taxon previously consisting of a number of geographically distinct infra-specific taxa. Cluster and principal component analyses of 99 populations revealed the aggregate to be best represented by two subspecies:A.angustifoliasubsp.angustifolia(a combination of the previously recognized subspeciesangustifolia,attenuata,sornborgeri,intermedia,iljinii, andalpinaandA.plantaginea) andA.angustifoliasubsp.tomentosa.Arnica angustifoliasubsp.angustifoliais polymorphic and varied in ploidy level and foliar flavonoid chemistry. No significant differences were found among the means of 14 characters in plants collected from six broadly delimited geographic areas. Four cytotypes (2n = 38, 57, 76, and 95) and seven flavonoid glycosides (five flavonols and two flavones) were discerned. The aggregate is predominantly agamospermous with amphimictic phases in unglaciated Alaska and west central Yukon. Disjunct distributions are probably the result of survival in refugia during the late Wisconsinan.

ISSN:0008-4026    

DOI:10.1139/b88-004

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The effects of beaver cutting on forest succession were studied on the banks of the lower Chippewa River in west central Wisconsin, U.S.A. Beavers were often found to be selective in their choice of woody plants, preferring ash and yellowbud hickory over all other species present. The effect of beaver cutting on tree density was substantial, with greatly reduced densities of trees in areas inhabited by beavers. The effects of beaver on the predicted composition of future generations of trees was also substantial. A major reduction in density is predicted for future populations of ash, hickory, and hackberry in areas of beaver activity, with a concomitant increase in the density of basswood and elm and possibly silver maple and prickly ash.

ISSN:0008-4026    

DOI:10.1139/b88-005

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Rhabdocline parkeriSherwood-Pike, Stone, & Carroll, an endophyte of Douglas-fir, infects healthy foliage by direct penetration of the host epidermal cell wall. Penetration is accomplished by a very fine penetration hypha. Intracellular infections are established in a single epidermal cell and result in the death of the cell. Haustoria lacking neckbands are produced from the intracellular hyphae at the onset of needle senescence. The intracellular hyphae contain large quantities of stored lipid and numerous mitochondria and peroxisomes. Although not growing, the hyphae appear to be metabolically active. Douglas-fir epidermal cells are alive at maturity and contain rudimentary chloroplasts. Small quantities of lipids and starch are present in the healthy epidermal cells. The large central vacuole of the epidermal cells contains primarily condensed tannins and tannin precursors.

ISSN:0008-4026    

DOI:10.1139/b88-006

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The survival and growth of ectomycorrhizal and ectendomycorrhizal red pine (Pinus resinosaAit.) seedlings transplanted from a nursery onto iron tailings were examined. Seedlings were inoculated with the E-strain fungus BDG-58 (Complexipessp. Walker emend. Yang & Korf),Phialophora finlandiaWang & Wilcox,Pisolithus tinctorius(Pers.) Coker & Couch, orSuillus subluteus(Peck) Snell ex Slipp & Snell. The first two isolates are ectendomycorrhizal fungi and the last two ectomycorrhizal fungi. Two-year field data on the tailings indicated a mycorrhizal treatment effect only in root-collar diameter at the end of the first growing season. The mycorrhizal treatments had a higher survival rate than the controls, with BDG-58 andPh.finlandiaseedlings having the greatest percent survival. Results from freehand root sections indicated that ectendomycorrhizae persisted in young roots of 4-year-old red pine seedlings that had been transplanted 2 years previously.

ISSN:0008-4026    

DOI:10.1139/b88-007

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Two strains of flax rust,Melampsora lini, designated strains CH5and I, were found to possess a number of double-stranded (ds) RNAs. A third strain, LMS, lacked dsRNAs. Sexual transmission of the dsRNAs was investigated by examining the dsRNAs in progeny obtained by selling and by intercrossing strains CH5and I. The results allow the dsRNAs in each strain to be assigned to transmission units, with strain CH5possessing two such units (designated L and C) and strain I three units (L, A, and B). The L unit consists of a single large dsRNA (about 4800 base pairs), while the other units (A, B, and C) each consist of a set of five to seven smaller dsRNAs, which taken together, total approximately 8000–9000 base pairs. The L unit in both strains was transmitted to all sexual progeny, whereas the multisegment units, A, B, and C, were transmitted to only some of the progeny. The A and C units were transmitted only via recipient pycnia ("maternal" inheritance), but transmission of the B unit occurred through both donor and recipient pycnia. Asexual transmission did not always occur, since one of five sublines of strain I lacked the B set. The dsRNAs were shown to be "infectious," since strain LMS acquired dsRNAs when grown on the same plant as strain I.

ISSN:0008-4026    

DOI:10.1139/b88-008

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

WhenVerticillium dahliaeKleb. was grown under a negative pressure potential of −0.039 MPa, conidial production increased 800% over that of untreated control fungus. The increased production occurred when the fungus was grown on Czapek Dox broth, on sugar-maple sap, or on sugar-maple sap amended with asparagine. Fungal survival within a host is discussed in light of the data.

ISSN:0008-4026    

DOI:10.1139/b88-009

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Pithomyces chartarum(Berk. & Curt.) M. B. Ellis was isolated from bluegrass sod (Poa pratensisL.) in Illinois, Indiana, and Wisconsin during July and August 1986. This is the first report ofPithomyces chartarumin the north central United States and the first report of the fungus in bluegrass sod. The fungus appears to be a saprophyte on senescent bluegrass leaves; its interest as a possible mycotoxin producer is underlined.

ISSN:0008-4026    

DOI:10.1139/b88-010

出版商:NRC Research Press    

年代:1988

数据来源: NRC