摘要:

Lasthenia(Compositae: Helenieae), a western North American‐Chilean genus of 16 species, produces 22 flavonoid glycosides. Flavonoids are the chalcones butein and okanin, the aurones maritimetin and sulfuretin, the flavone luteolin, and the flavonols kaempferol, quercetin, and patuletin. The presence or absence of various of these classes of compounds in general follows sectional alignments in the genus, confirms affinities based on morphological and cytological evidence, and suggests relationships of problematical species. Intraspecific variation in flavonoid constituents occurs in several species, and in one taxon intrapopulation variation seems to exist as well. Evolution withinLastheniahas been associated with a loss of the ability to produce or accumulate luteolin, chalcones, and aurones; an increase in diversity of quercetin glycosides; acquisition of the ability to produce patuletin; and an elaboration of glycosylation patterns of patuletin.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12276.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

The classical pteridophyte apical cell theory of meristem organization is not flexible or realistic enough to encompass the variation encountered in a comprehensive anatomical survey of fern meristems. The meristems of 28 taxa of ferns (both eu‐ and leptosporangiate) were studied. This analysis has led to the formulation of the concept of a promeristem composed of two zones: the surface and subsurface initials. This concept is flexible and sufficient to describe the variation encountered in the ferns as a group. No differences in promeristem organization were observed in plants with various rhizome morphology (e.g., upright and radial; prostrate and dorsiventral). Marking experiments, performed on living surface cells of fern promeristems, correlate with anatomical observations of division planes in the promeristem and indicate that the central, surface initials are not quiescent. Feulgen determinations indicate thatNephrolepisstolons have no endomitotically polyploid cells in the promeristem. Additional work is needed before a generalization can be made concerning ploidy levels in a more typical fern apex. Ferns, in general, have a zoned promeristem which is parallel to the zonation described for higher vascular plants.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12277.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

A study of a mutant variety ofZea mays(ON8147) revealed that the mutant plants, in contrast with normal maize plants, do not exhibit a light‐induced increase in the rate of transpiration, and that the ontogeny of the stomatal complex is abnormal. In later stages of differentiation, the guard cells of mutant plants deteriorate, leaving the mature stomata with only the two subsidiary cells. The subsidiary cells in stomata of mutant leaves are similar to those of normal leaves with respect to their capacity to accumulate K+in the dark, but they do not lose K+in the light, as do subsidiary cells of stomata of nonmutant plants. It is suggested that impairment of guard cell function causes death of the mutant plant seedlings primarily by restricting CO2entry into the leaf.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12278.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

Three mutants ofImpatiens sultani(named as ‘Orange', ‘Crimson', and ‘Pink') show an unusually wide spectrum of aberrations in microsporogenesis. These aberrations range from premeiotic cytomixis to meiotic and postmeiotic irregularities such as precocious disjunction, tripolar separation of chromosomes, chromosome bridges, various patterns of atypical cytokinesis, supernumerary divisions of the meiotic products, and irregular divisions in the microspore. As a result of these abnormalities Orange is partially and Crimson and Pink are completely pollen sterile. The stigmas of Pink, besides, do not support pollen germination. The failure of pollen germination is attributed to the defective stigmatic fluid of Pink, which, compared to that of Orange and Crimson lacks organic compounds absorbing UV light at 261 nm. This constitutive deficiency in stigmatic fluid appears to be a little investigated facet of female sterility.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12279.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

Relative water content, resistance to gas transfer, stomatal spacing, and other characteristics of primary bean leaves were studied in relation to ozone sensitivity and injury. Cells of primary bean leaves are maximally sensitive to ozone exposure 9–10 days after germination under our experimental conditions. The stage of maximum sensitivity was not correlated with changes in stomatal number or resistance on either adaxial or abaxial leaf surfaces. It was deduced that bean leaf sensitivity was a function of more internal circumstances, and gas exchange was never the limiting factor through the developmental period studied. Changes in resistance were not significantly altered by ozone levels that produced no visible injury. After exposure to high ozone doses, a decrease in adaxial resistance occurred apparently as a result of palisade and epidermal cell lysis. Normally most gas exchange occurs through the adaxial surface. A 10 % decrease in relative water content accompanying a 60‐min ozone exposure of 0.55 ppm could not be explained physiologically on the basis of cell injury as no visible leaf injury occurred.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12280.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

At least eleven somatic compatibility loci exist in the myxomyceteDidymium iridis.Cell fusion is controlled by at least seven fusion loci (Fus1–Fus7). Cytoplasmic compatibility is controlled by at least four clear‐zone loci (Cz1–Cz4). Plasmodia with identical phenotypes at all seven fusion loci, but different phenotypes at the clear‐zone loci, will fuse temporarily, but fusion is soon blocked by cytoplasmic reactions which prevent complete mixing. Areas which contain cytoplasm from two incompatible Plasmodia become clearly delineated from healthy cytoplasm. Such areas, termed clear zones, have been isolated and found to recover. If clear zones are sectioned into several small pieces, not all pieces will recover, indicating that toxic cytoplasmic reactions have occurred. Plasmodial fusion studies and F1studies of recovered clear zones indicate that the clear‐zone loci may also control nuclear survival in heterokaryons.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12281.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

The spatial relationships observed during microsporogenesis and pollen development inSorghum bicolorindicate that a strong polarization exists in the anther locule and within individual microspores and pollen grains. During all developmental stages, each sporogenous cell and its derivatives lie continuously adjacent to the tapetum. The microspores and pollen grains form depressions in the tapetal orbicular wall. When the single pore of each microspore is initiated, as a gap in the primexine, it too lies adjacent to the tapetum and remains tightly appressed there until pollen maturity. A sequence of polar phenomena in microspores and pollen grains centers on an axis through the pore and perpendicular to the tapetal surface. These events include migrations of the microspore and vegetative nuclei, initial placement of the generative cell opposite the pore and its later migration, and a polar engorgement process whereby the pore end of the pollen grain (adjacent to the tapetum) fills with starch grains first. The tapetal cytoplasm completely degenerates at precisely the time of pollen engorgement, and its degradation products are believed to be available for pollen uptake at this time. The continuous association of the sporogenous cells or their cellular derivatives and their pores with the tapetum is thought to play an indispensible role in pollen development in sorghum and probably in all other grasses as well. The consistent position of the pore adjacent to the tapetum should be considered another common feature of microsporogenesis in the Gramineae. The characteristic exine pattern forms over the operculum and annulus of the pore, but the lamellae, which underlie the annulus, form a highly modified multilayered nexine. Membrane‐like cores are observed in these lamellae and are believed to be involved in the initiation of sporopollenin deposition, but they are obliterated by pollen maturity. Neither the cores nor the lamellae are found in other parts of the pore or in the nonapertured wall.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12282.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

Limnobium spongiaproduces upright vegetative axes and prostrate stolons. The upright axes bear new stolons, whereas the stolons bear new upright axes and fertile and sterile branching systems. Upright axes and fertile and sterile branching systems are all interpreted to have sympodial growth. However, it was not determined whether growth of stolons is monopodial or sympodial. Both stolons and upright axes branch in alternate plastochrons, and branching is achieved solely by the bifurcation of apical meristems. Each meristematic bifurcation is interpreted to represent the formation of a precocious lateral bud. The upright axes develop from presumed precocious lateral buds on stolons, whereas such buds on upright axes produce renewal shoots.Limnobium spongiaexhibits a marked degree of mirror‐image symmetry.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12283.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

Removal of the rostellum following pollination does not prevent stigmatic closure inCymbidiumflowers and has a minimal effect on straightening of the gynostemium (column). However, this treatment does depress anthocyanin levels in both gynostemia and labella. Excision of the rostellum 30 or 60 min after pollination has a more pronounced effect than removal after 150 min. Stigmatic closure is not inhibited by removal of the gynostemium tip, but column swelling is reduced. These findings are discussed relative to rostellar functions and theories regarding their origin.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12284.x

出版商:Wiley    

年代:1974

数据来源: WILEY

摘要:

A total of 235 accessions ofTripsacum dactyloides(L.) L. representing natural populations from 88 locations distributed throughout ten states of the United States were collected in the wild and studied morphologically and cytologically. Multivariate analysis of variance (MANOVA) was applied to 17 morphological characters recorded for 868 specimens from the 88 locations, which were further combined into 25 groups to facilitate analysis. Multivariate F ratios for six comparisons involving different groups were highly significant, indicating that the populations were significantly different on the basis of all 17 characters. Non‐significant MANOVA F ratios for two comparisons between sympatric diploid and polyploid accessions showed them to be morphologically similar. Discriminant function (DF) analysis was employed to determine which characters contributed towards group discrimination. No one variable was found to distinguish between groups; rather, a combination of characters was necessary, and the combination changed with each comparison. Accessions were mainly either diploid (2n= 36) or tetraploid (2n= 72), with two triploids (2n= 54) reported from separate locations in Texas. Cytological data revealed that diploids and tetraploids occupy a more sympatric distribution than previously supposed. Morphological analysis suggested that diploids could not always be distinguished from polyploids on the basis of morphology alone, unless the appropriate characters were used. Information from cytological and morphological data showedTripsacum dactyloidesto be composed of many populations covering a wide range of variability, with each population possessing a characteristic combination of morphological attributes. It was concluded thatT. dactyloidescan be most meaningfully analyzed in terms of particular geographic regions, rather than attempting to elucidate natural relationships by correlating data from the entire United States.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1974.tb12285.x

出版商:Wiley    

年代:1974

数据来源: WILEY