摘要:

Control over elongation inAvenacoleoptile andPisumepicotyl segments by cyclic far-red light treatment is dependent on the timing of successive irradiations and independent of total energy. The effect of each far-red irradiation in a cycle is cumulative. Maximum efficiency of far-red light in a cycle is obtained when the light treatments follow within 2 to 3 h of each other. Additional increments of elongation may also be obtained by successive red light treatment only when presented at least 8 to 9 h apart. The effect of a single far-red treatment is to establish a maximum rate of elongation which is maintained for no more than 3 h. The results offer support for the hypothesis that low-energy phytochrome mediated responses result from maintenance of low but maximally effective levels of Pfrand that Pfrdestruction is essentially independent of physiological action.

ISSN:0008-4026    

DOI:10.1139/b72-001

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The date of publication of the genusCallistopollenitesprecedes that of the genusPseudoexpressipollisby about 3 months. ThusCallistopollenitesS. K. Srivastava has priority overPseudoexpressipollisKrutzsch.The genusTricolporitesCookson has been considered here as a valid monotypic genus because it meets the requirements stipulated by the International Code of Botanical Nomenclature.The acceptable spelling and taxonomic position of the genusCarpinipitesS. K. Srivastava have been discussed.

ISSN:0008-4026    

DOI:10.1139/b72-002

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

We have demonstrated that the reduced net rate of oxygen uptake observed when DCMU-poisonedChlorellaare illuminated is a result of an inhibition of respiration rather than residual photosynthetic oxygen evolution. The action spectrum of the effect demonstrates that chlorophyllais the main photoreceptor, implicating system I of photosynthesis. Studies using PMS, which is known to stimulate cyclic photophosphorylation by photosystem I, show that the respiratory inhibition is caused by a change in the intracellular ATP/ADP balance as a result of cyclic photophosphorylation.

ISSN:0008-4026    

DOI:10.1139/b72-003

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

As many potato seedlings became infected with leaf roll virus when infested with viruliferous aphids (Myzus persicaeSulz.) by a fast cut-leaf method, as when infested by a slower brush method. More plants, however, became infected when infested at emergence than at any of five other periods of growth including that of sprouts.In recovery tests, more infected plants were detected by testing sprouts and excised leaves of 7-week-old plants than by testing newly emerged plants. Any of the small leaves from the upper 6 cm of infected plants were equally good sources of virus for aphids. Also, when tests were made for 18 successive weeks after inoculation on infected Netted Gem plants, it was only during the first 9 weeks and at the 13th week that all infected plants were detected.No differences resulted, in the number of infected plants produced, when eyes were grown from the bud or stem end or from the middle of infected tubers.

ISSN:0008-4026    

DOI:10.1139/b72-004

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Hypocotyls of 76 species of dicotyledonous seedlings, drawn from 30 families, were surveyed for tissue site of red pigmentation. In 42 species, red pigments were borne by a single layer of cells. Two layers were pigmented in 19 species and several layers in 15. Hypocotyl extracts of 61 species were analyzed for anthocyanidins. Pelargonidin was the major pigment in only one. Cyanidin alone or in combination with pelargonidin or delphinidin was identified in 37 species and probably present in 11 more. Delphinidin and its derivatives malvidin and petunidin were found in members of the Solanaceae. Delphinidin and malvidin were also major pigments in twoPhaseolusspecies. Anthocyanidins were not detected in the four members of the Centrospermae examined.

ISSN:0008-4026    

DOI:10.1139/b72-005

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The mature spore ofChoanephora cucurbitarumpossesses a thick three-layered cell wall which is different from the hyphal wall. Its germination is accompanied by the formation of a thin, elastic inner layer which extends around the emerging germ tube and the growing hypha. High resolution autoradiography showed that3H N-acetyl-glucosamine, a precursor of chitin, was incorporated preferentially in the thin inner layer of the conidial wall and also in the wall of the growing hypha. When the label was fed to the infected cells, at different intervals, 18, 24, 30 h after inoculation, grains were observed in the sheath area around the haustorium ofPiptocephalis virginiana, only at 24 and 30 h after inoculation. The significance of these results in relation to the origin and composition of the haustorial sheath is discussed.

ISSN:0008-4026    

DOI:10.1139/b72-006

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Tilletiaria anomalagen. et sp. nov. is described. The species is characterized by aculeate teliospores similar to those of some Ustilaginales. The transversely septate metabasidia, sterigmata, and basidiospores are as in the Auriculariaceae. The hyphal cells are monokaryotic and haploid; fertile branches are subtended by a fusion bridge through which dikaryotization occurs.

ISSN:0008-4026    

DOI:10.1139/b72-007

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The type species ofDoliomyces, D. senegalensis, is redescribed.Doliomyces mysorensissp. nov. is described from decaying leaves ofArtocarpus integrifolia. Conidium ontogeny in this species is identical with that of some species ofPestalotiaandPestalotiopsis.

ISSN:0008-4026    

DOI:10.1139/b72-008

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

More isolates ofGnomonia fructicolaformed perithecia on Leonian's agar than on potato-dextrose or cornmeal agar. Fortifying these media with a strawberry petiole extract stimulated perithecium formation on potato-dextrose agar but not on Leonian's or cornmeal agar. All eight isolates studied produced perithecia on strawberry petioles and one produced them only on petioles. The eight isolates segregated into four cultural races according to their ability to form perithecia on the agar media and petioles. This explains why different media have been reported to be best for perithecium production in this fungus.

ISSN:0008-4026    

DOI:10.1139/b72-009

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A study was made of gibberellin action on germinating lettuce seed. Results obtained by observing the total response of a seed population to the inhibitor cycloheximide could be interpreted as being indicative of gibberellin-induced protein synthesis. Biochemical studies did not substantiate this interpretation. Quantitative studies involving incorporation of leucine-4, 5-T in protein and qualitative studies using polyacrylamide gel electrophoresis suggest that there are no major GA-induced changes in protein synthesis before visible germination.

ISSN:0008-4026    

DOI:10.1139/b72-010

出版商:NRC Research Press    

年代:1972

数据来源: NRC