摘要:

Each basidiospore ofGymnosporangium juniperi-virginianaecontains many ribosomes as well as lipid droplets, mitochondria, small vesicles, endoplasmic reticula, and structures thought to be microbodies. Mature spores are either uninucleate or binucleate although larger, tetranucleate spores were occasionally observed. The spore wall appears as a thin layer except around the hilar region where two layers are evident. Germination is almost always lateral although no germ pore region was noted in the wall. Vacuolation takes place during germination and lipid bodies disappear. The wall of the germ tube arising from the spore is continuous with that of the spore. A large number of vesicles is present in the germ tube. Basidiospores may also germinate by repetition.

ISSN:0008-4026    

DOI:10.1139/b77-124

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The ultrastructure of the epidermis and stomatal complex ofAbies balsamea(balsam fir) was examined. Needles were fixed at the time of emergence from the bud and at intervals thereafter. Epidermal cells in the youngest needles examined had a prominent nucleus, with several nucleoli, ribosome-rich cytoplasm, a few rudimentary chloroplasts. and small vesicles with osmiophilic material. With maturation, the vacuole expanded to nearly fill the cell leaving only a thin layer of cytoplasm around the wall. The walls underwent a high degree of thickening, and a wax and cuticle layer developed.Guard cells were located below the needle surface with specialized subsidiary cells overarching them and creating a stomatal antechamber. This cavity contained wax formations deposited even before the needles emerged from the bud scales. Guard cells were substantially matured at the time of bud break with a characteristic pattern of wall structure. Chloroplasts, which develop multiple starch grains, were abundant near the polar ends of the cells. Radial micellation of the walls was pronounced. Specialized 'hinge' areas were noted. A region on the ventral wall, facing the pore, lacked lignification and showed distinct bends in the fibrillar material, which may be associated with opening and closing the stomate.

ISSN:0008-4026    

DOI:10.1139/b77-125

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Besides a trimerous calyx and corolla, the mature flower exhibits a polyandric androecium and an apocarpous gynoecium consisting of a whorl of carpels. Yet the primary pattern of the flower is completely trimerous and tetracyclic. After the inception of three sepals and three petals, three antesepalous primary androecial primordia are initiated each of which forms three stamens (i.e. secondary androecial primordia). Opposite these three groups of three stamen primordia, three groups of three carpels are initiated, possibly on three extremely inconspicuous primary gynoecial primordia. Additional carpel primordia are formed in varying numbers between the original three groups. Even before carpel inception, the three primary androecial primordia merge laterally thus forming an androecial ring. Additional stamen primordia arise on this ring first between the three groups of three stamen primordia and then in centrifugal direction as the androecial ring broadens basally. Eventually four whorls of stamens and two to three whorls of staminodia are formed secondarily on the androecial ring which arose from the primary primordia. Morphogenesis and construction of the flowers ofLimnocharis flavadiffers in two major respects from those of all other taxa of the Alismatales studied thus far: (1) there are no stamen pairs primarily associated with the petals, and (2) the first-formed carpel primordia do not alternate with the stamen primordia of the preceding whorl, thus violating Hofmeister's rule of alternation.

ISSN:0008-4026    

DOI:10.1139/b77-126

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The reproductive region ofSagittaria cuneatais basically trimerous. This trimery is exhibited in the arrangement of the bracts, sepals, petals, pairs of stamens in the male flower, and pairs of staminodia in the female flower. In the male flower after the inception of three sepal primordia, each of the three petal primordia arises with one pair of stamen primordia on an alternisepalous bulge of the floral apex, i.e., a petal–stamen (CA) primordium. Subsequent stamen primordia are formed in alternation with the six first-formed primordia. If, for convenience sake, the first six primordia are referred to as the first whorl of stamens up to four additional whorls may be produced. Depending on the size of the floral bud, the third and fourth whorls (if present) consist of two to six stamen primordia, whereas the fifth whorl (if present) contains one to five stamen primordia. Finally, primordia of pistillodes are formed in varying numbers. In the female flower the presence of CA primordia could not be as clearly established as in the male flower. However, again each petal primordium is definitely associated with a pair of antepetalous primordia. The latter primordia develop into staminodia. In alternation with the first six staminodia six additional staminodia are formed and then again in alternation many whorls of pistils (carpels). Even in the mature flower the basic trimery is reflected in the triangular shape of the globose and massive gynoecium. From a developmental point of view, the male and female flowers are primarily trimerous. The polyandric androecium and the large pleiomerous gynoecium are superimposed on the primary trimery. It appears quite possible that this developmental modification also reflects a phylogenetic derivation. This means that the pleiomerous gynoecium and androecium are not primitive but rather advanced. There is no indication of a spiral arrangement of stamens and carpels.Whereas the foliage leaves, bracts, and sepals are initiated as dorsiventral primordia, the petals, stamens, staminodia, pistils, and pistillodes arise as more or less hemispherical mounds and become dorsiventral thereafter. The vegetative apices, inflorescence apices and the floral apices have a two-layered tunica over a massive corpus. Foliage leaves, bracts, sepals, petals, stamens, staminodia, carpels, and pistillodes are initiated by periclinal divisions in the second tunica layer. In the case of the stamens and staminodia the corpus may also contribute. Ovules are initiated by periclinal divisions of the second layer of the carpel primordium.

ISSN:0008-4026    

DOI:10.1139/b77-127

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The primordia of the floral appendages are initiated in an acropetal succession. Members of the same whorl appear nearly simultaneously. The gynoecial whorl and the two staminal whorls are trimerous, whereas the perianth consists only of two anteriolateral tepals. However, the posterior (adaxial) tepal may be present as an extremely reduced buttress whose growth becomes arrested immediately after its inception. If this somewhat questionable tepal rudiment is included we have a perfectly trimerous and tetracyclic flower with alternation of successive whorls. Subtending bracts of the flowers are completely missing in all developmental stages. While the tepal primordia are dorsiventral from their inception, the stamen and pistil (carpel) primordia originate as hemispherical mounds which become dorsiventral in subsequent stages of development. Each pistil (carpel) primordium becomes horseshoe shaped. As the margins grow up and contact they fuse postgenitally. No cross zone is formed. Placentation is submarginal. InA. natanseight ovules are formed and inA. undulatusonly two arise; all ovules are bitegmic. The floral apices have a two-layered tunica up to the stage of pistil formation. The inception of all floral appendages (including the ovules) occurs by periclinal cell division in the second tunica layer. The third layer (corpus) may contribute to the formation of the stamens and pistils. Each appendage primordium receives only one procambial strand which begins to differentiate after the inception of the primordium. The questionable rudimentary tepal buttress lacks a procambial strand. Apparently it does not reach the developmental stage at which procambial induction occurs. From the point of view of floral development, the two species ofAponogetondiffer drastically from members of the Alismatales studied so far. Among the Helobiae, the Aponogetonaceae appear to be most closely related to the Scheuchzeriaceae and the Juncaginaceae (Triglochinaceae).

ISSN:0008-4026    

DOI:10.1139/b77-128

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

At different stages in the growth cycle the short-term translocation pattern of14C-labelled assimilates was determined together with carbohydrate concentration changes in twoSolidago canadensisL. populations growing on abandoned pasture sites in southern Ontario. Tagging whole shoots with14C revealed that (1) a high (50–70%) proportion of assimilated carbon is retained by leaf tissue, (2) the proportion of assimilated carbon incorporated in the aerial stem increases during shoot extension but declines later during inflorescence development, (3) the proportion of assimilated carbon translocated to the inflorescence during flowering and fruiting is considerably in excess of its dry weight contribution, and (4) underground tissues, even the new rhizomes which develop in late season, account for a comparatively small proportion of assimilated carbon. Tagging individual leaves with14C during reproductive development showed that the proportion of leaves exporting assimilates to the new rhizome system progressively increases, while that supplying the inflorescence decreases, after August and that individual leaves do not simultaneously export carbon to the inflorescence and new rhizomes. Carbohydrate analysis showed that early shoot development is associated with a marked reduction in carbohydrate status of both roots and rhizomes, which is subsequently restored, and that roots and rhizomes retain a storage function for at least 2 and 3 years, respectively.

ISSN:0008-4026    

DOI:10.1139/b77-129

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

As the seedling primary root of maize inbred W64A elongates, basal and augmented K+(86Rb) uptake rates increase in regions increasingly distant from the apex and in regions at a fixed distance from the advancing apex. The pH-dependent process of augmentation requires aeration, begins without a lag period at pH 6, and is linear for 90 to 120 min. The augmentation potential of W64A(N) midzone root segments is minimal at 0.5 mMexternal K+concentration and increases toward higher and lower external K+concentrations. Augmentation is prevented at pH 4 in the Texas cytoplasmic male-sterile (T) version of inbred W64A but not in the male-fertile (N) version.Protein synthesis is required for development of K+(86Rb) uptake augmentation and probably also for maintenance of the augmented rate after development but apparently not for its expression. Inhibition of the maintenance of the augmented rate by low concentrations of chloramphenicol or cycloheximide does not prevent subsequent augmentation in their absence.Augmentation of amino acid uptake is not inhibited by 100 μg/ml chloramphenicol or 10 μg/ml cycloheximide, but augmentation of amino acid incorporation is inhibited by each. Augmentation of amino acid influx is sensitive to the toxin ofHelminthosporium maydis, race T, in T roots but not in N roots, whereas augmentation of amino acid incorporation is only slightly more toxin-sensitive in T than in N root segments.

ISSN:0008-4026    

DOI:10.1139/b77-130

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Sclerotia ofSclerotium rolfsiigerminated without the addition of an exogenous nutrient source. The germinating sclerotia excreted sugars and amino acids to the surrounding medium. Continuous washing of sclerotia prevented germination. In germinating sclerotia, the rate of uptake and incorporation into macromolecules of [3H]uridine and[3H]leucine was very low in the first 6 h but increased rapidly during the next 6 h. Electron microscopy of germinating sclerotial slices revealed that only the granulated medullar cells were involved in germ-tube formation. The germination tubes were very electron-dense and had a large number of mitochondria near their tips. The huge vesicles of the cortex cells appeared almost empty in the germinating sclerotium. It is suggested that these cells serve as an external nutrient reservoir for the germination tubes.

ISSN:0008-4026    

DOI:10.1139/b77-131

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The magnesium level required to support full growth in batch suspension cultures of anIpomoeasp. (Morning Glory) cell line in 2% sucrose media was less than 0.3 mM. The uptake of magnesium increased with increasing magnesium in the medium, and with increasing pH at constant magnesium level. In medium containing 1.0 mM(24 mg/ℓ) magnesium, a culture kept at pH 4.7 absorbed 6 mg of magnesium in 150 h; the corresponding figure for a culture kept at pH 6.9 was 19 mg.Much of the excess magnesium taken up by cells grown at the 1.0 mMmagnesium level at various controlled pH levels could be extracted by grinding the cells in distilled water. The data suggest that under conditions of high magnesium supply and high pH these cells absorb large amounts (i.e. several milligrams per gram dry cells) of magnesium in excess of their requirement for growt

ISSN:0008-4026    

DOI:10.1139/b77-132

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Resistance to white pine blister rust in sugar pine is simply inherited and can be identified by distinct needle spot morphs. After artificial inoculation at 2 years of age, seedlings from selfed and full-sib families developed either 'fleck' spots, characterized by a pale, yellow margin with a necrotic fleck in the center, or they developed typical yellow or red spots (or both). Seedlings segregated for needle spot reaction in monohybrid ratios with fleck dominant. Mycelium in secondary needle tissues of fleck spots, in contrast to yellow and red spots, was relatively sparse and confined by dense tannin deposits. Bark infection and mortality was heavy on seedlings with yellow and red spots. On seedlings with fleck spots, no bark symptoms developed from secondary needle infection but small, abortive cankers did develop on some of these seedlings as a result of primary needle infection. These atypical cankers did not sporulate or spread extensively, and had healed by the 2nd year after inoculation. The gene responsible for the fleck reaction thus elicits a hypersensitive response in secondary needles and, apparently, in bark tissues as well.

ISSN:0008-4026    

DOI:10.1139/b77-133

出版商:NRC Research Press    

年代:1977

数据来源: NRC