摘要:

Four new species of Laboulbeniales occurring on beetles (Coleoptera) from Sulawesi (Celebes), Indonesia, are described and illustrated:Cucujomyces celebensissp.nov. parasitic onHyliotasp. (Cucujoidea, Cucujidae),Dimeromyces storkiisp.nov. parasitic onEustra matangaAndrewes andEustra plagiataSchm.-Goebel (Carabidae, Paussinae),Laboulbenia hammondiisp.nov. parasitic onOmadiusspp. (Cleridae), andRickia anthribidicolasp.nov. parasitic onHypseus vestitusJordan (Anthribidae, Anthribinae). All of the new species are compared with existing taxa. Of particular note isR.anthribidicola, which represents the first confirmed instance of parasitization by a laboulbenialean fungus on members of the hyperdiverse beetle family Anthribidae.Keywords: Laboulbeniales, Indonesia, Anthribidae.

ISSN:0008-4026    

DOI:10.1139/b96-011

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

The transition from alder (Alnus tenuifolia) to balsam poplar (Populus balsamifera) is a critical turning point in primary succession on river floodplains in interior Alaska. Associated with the change in plant species are large changes in N cycling. N-fixation and nitrification decrease and the system becomes N-limited, with NH4+dominating the inorganic N pool. Balsam poplar leaves contain large quantities of tannins and low molecular weight phenolic compounds. We evaluated the effect of these compounds on microbial respiration and N cycling in laboratory assays on soils from an alder-dominated site. Plant compounds were purified and applied to silica gel as an inert carrier. Both tannins and phenolics caused net N-immobilization over a 30-day assay. However, tannins inhibited respiration while phenolics stimulated it. There were no specific effects on nitrification. Thus, tannins acted as a general microbial inhibitor, while phenolics acted as a growth substrate. By inhibiting mineralization while stimulating immobilization, poplar secondary compounds may reduce soil N-availability during the transition betwen alder and poplar stages in succession.Keywords: respiration, mineralization, tannins, secondary chemicals, succession, plant–microbe interactions.

ISSN:0008-4026    

DOI:10.1139/b96-012

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

A high level of achene sterility, nonexserted anthers, and aborted pollen support the hybrid rank of a plant of unusual morphology from the Timiskaming district in northern Ontario. While the centrally involute leaves associate the plant unquestionably withCarex oligosperma, the waxy and papillate leaf surface associate it unquestionably withCarex rostrata, and various intermediate characteristics and circumstantial evidence provide further support for this parentage and a new natural hybrid. This new taxon has pistillate scales 1.7–2.4 mm wide, intermediate in width between the lanceolate scales ofC.rostrata, which are 1.3–1.6 mm wide, and the broadly triangular scales ofC.oligosperma, which are 3–4 mm wide. The perigynia correspond most closely with those ofC.oligosperma, but the pistillate spikes with 8–41 flowers resemble more closely those of theC.rostrataparent.Carex oligosperma×C.rostrataresemblesC.vesicariabut differs in its long creeping rhizomes, narrower involute leaves, and shorter ligules. A key toCarexsectionVesicariaein northern Ontario is included, as well as a description of the new hybrid. The hybrids occupied an inundated zone between a higher solid sphagnum carpet dominated byC.oligospermaand a quaking mat occupied byC.rostrata.Keywords:Carex, hybridization, systematics, morphology, Ontario, Canada.

ISSN:0008-4026    

DOI:10.1139/b96-013

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Damage to the carpel surface of the developing cotton boll such as that caused by infection with aflatoxigenicAspergillusspp. results in activation of the lipoxygenase pathway. Lipoxygenase pathway activation generates a series of diverse, antifungal, volatile aldehydes that affect the growth ofAspergillus flavusand indirectly has an effect on aflatoxin production. Analysis of the head space volatile aldehydes by gas chromatography – mass spectrometry trapped during a 1-h sampling period of carpel surfaces of 23- to 35-day developing cotton bolls treated with exogenous lipase resulted in the identifications of C5–C9alkanals and alkenals including hexanal andtrans-2-hexenal. Hexanal concentrations generated in lipase-treated bolls resulted in a two-fold increase of hexanal production. The effects oftrans-2-hexenal on aflatoxin production were determined on intact 30-day-old developing cotton bolls treated with 2.2–8.6 μmol amounts oftrans-2-hexenal and inoculated with aflatoxigenicAspergillusin three different treatment systems.Trans-2-hexenal was placed on the developing cotton boll (i) 24 h before, (ii) 24 h after, or (iii) simultaneously with fungal inoculation. After a 3-week incubation on the intact cotton plants, bolls were harvested and aflatoxin determinations were conducted on cottonseeds from the bolls. The results suggest that pretreatment of the boll withtrans-2-hexenal initiates a strong antagonism to aflatoxin formation due to the antifungal effects on the growth of the fungus in developing cotton bolls. These results also demonstrate a series of host-plant defense responses that suggest the possible involvement of the lipoxygenase pathway in interactions between aflatoxigenicAspergillusand the cotton plant.Keywords: aflatoxin,Aspergillus flavus, cotton (Gossypium hirsutum), lipoxygenase (LOX) pathway, lipids.

ISSN:0008-4026    

DOI:10.1139/b96-014

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Endophytic fungi were isolated from the needles of 45 species and varieties of the genusPinusplanted in an arboretum, and the species composition of the endophytes were compared among the pines examined. In general,Leptostromaspp. andCenangium ferruginosumFr. ex Fr. were dominant in the middle segment of the needle, while on the basal segment,Phialocephalasp. was more frequently isolated than the other two taxa.Leptostromaspp. seemed to be excluded from the basal segment byPhialocephalasp. The endophytic mycobiota of pines belonging to the same taxonomic group was similar. The taxonomic affinities of the host pines strongly affected the colonization patterns of the endophytes, while the effects of factors such as sampling date, tree age, and location in the stand were much weaker.Keywords: endophytic fungi,Pinus, host preference.

ISSN:0008-4026    

DOI:10.1139/b96-015

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Pollination drops are secreted from the ovules of interior spruce (Picea glaucaorPicea engelmanniiand their hybrid) as seed cones begin to close at the end of the pollination period. Secreted pollination drops persist within spaces surrounding the micropylar opening in closed seed cones. Saccate pollen floats into the micropyle within the pollination drop. Pollination drops become voluminous enough, within the enclosed spaces, to scavenge pollen adhering to the micropylar arms and other surfaces in proximity with the micropyle. Scavenging of pollen from cone surfaces adjacent to the integuments is sometimes facilitated by rainwater that can float pollen into the opening of the micropyle before cone closure and pollination drop secretion. In practice, periodic, light misting of seed orchard trees during seed cone receptivity might increase pollination efficiency by mimicking rainwater involvement in the pollination mechanism. Rainwater involvement in pollination of some modern conifers may reflect a similar situation in the pollination mechanisms of ancestral conifers. Environments with limited rainfall combined with the requirement for moisture in the pollination mechanism may have provided the selective pressure for evolution of the pollination drop.Keywords: pollination drop,Picea, conifer, sacci.

ISSN:0008-4026    

DOI:10.1139/b96-016

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

The 3′ region of thematK gene from 17 species, representing 13 tribes and six subfamilies of the Poaceae, is used to investigate the potential of the gene in addressing systematic questions in the family. The aligned sequences were analyzed by the Wagner parsimony methods usingPAUPandPHYLIPand by the neighbor-joining method. Out of the 583 bp sequenced, 30% were variable and 14.9% were informative. The strict consensus tree, rooted byJoinvillea(Joinvilleaceae), showed well-resolved major clades that represent the grass subfamilies. The bambusoidPhyllostachysappeared as a basal clade in the family.Oryzadiverged either before or after the Pooideae in the parsimony and neighbor-joining methods, respectively. The three members of the Pooideae grouped in a monophyletic lineage in both analyses.Arundo(Arundinoideae) was basal to the subfamilies Panicoideae and Chloridoideae. Analysis of the various types of DNA mutations underscores the potential of thematK gene in providing insight into grass systematic and evolution.Keywords:matK, Poaceae, grasses, phylogeny, chloroplast, DNA sequence.

ISSN:0008-4026    

DOI:10.1139/b96-017

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Experiments were conducted under field conditions to assess selected growth, physiological, and biochemical responses of three leguminous plants (Vigna radiataL. (Wilczek) cv. PS-16,Phaseolus mungoL. (Hepper) cv. Mash-48, andGlycine maxL. (Merr.) cv. Punjab 1) to enhanced UV-B radiation equivalent to 15% ozone depletion at 25°N latitude. Enhanced UV-B radiation adversely affected growth characteristics, chlorophyll and carotenoid contents, photosynthetic rate, ascorbic acid content, and catalase activity, whereas a reverse trend was found for phenol content and peroxidase activity in all three species. However, the magnitudes of increases or decreases were different among species, and there was no direct relationship between growth and biochemical responses across species.Keywords: chlorophyll,Glycine max, net photosynthesis,Phaseolus mungo, plant growth,Vigna radiata.

ISSN:0008-4026    

DOI:10.1139/b96-018

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Stigma and style morphohistological features of the sixRomuleaspecies (Iridaceae) living in France and their various pollination modes, described for the first time in this study, were considered with regard to nectar floral apparatus features, also described for the first time here. This apparatus was also variable among taxa. The results confirmed the self-compatibility of all species as well as the almost obligate autogamy among the small-flower species, and the allogamy among the gynodioic large-flower species. This study represents a new and necessary step in the reconstitution of the speciation and genus evolution.Keywords:Romulea, reproductive systems, autogamy, allogamy, evolution, speciation. [Journal translation]

ISSN:0008-4026    

DOI:10.1139/b96-019

出版商:NRC Research Press    

年代:1996

数据来源: NRC

摘要:

Plant size and flower production were compared between female and hermaphroditic plants of two gynodioeciousChionographis. Frequency distribution of size and minimum size class of flowering plants were not different between two sex morphs in bothChionographis. InC.japonicassp.hisauchiana, females produced more ovuliferous flowers than hermaphrodites, although the total number of flowers were not significantly different between two sex morphs. In contrast, hermaphrodites ofC.japonicavar.kurohimensisexceeded females in the total number of flowers, whereas the number of ovuliferous flowers was not significantly different between two sex morphs. Reproductive effort at flowering season is not different between females and hermaphrodites. These little differences in secondary sex characters, compared with dioecious species, are probably due to the selfing of hermaphrodites and weaknesses in gender specialization.Keywords:Chionographis, flower production, gynodioecy, plant size, secondary sex characters.

ISSN:0008-4026    

DOI:10.1139/b96-020

出版商:NRC Research Press    

年代:1996

数据来源: NRC