摘要:

The cellular distribution of the starch biosynthetic and degradative enzymes in protoplasts prepared from maize leaf mesophyll and bundle sheath cells was investigated. In conformity with the cellular distribution of starch, starch biosynthetic enzymes (soluble starch synthase, ADPglucose pyrophosphorylase, branching enzyme and starch Phosphorylase) were exclusively localized in the bundle sheath cells. In contrast, starch degradative enzymes (α‐amylase, β‐amylase and debranching enzyme) were present in both types of leaf cells. Isolated chloroplasts from bundle sheath cells were shown to contain 100% of the starch biosynthetic enzymes. However, approximately 60% of the activity of degradative enzymes and 67% of the activity of starch Phosphorylase was localized in bundle sheath chloroplasts.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08517.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Twenty four quantitative characteristics of 95 specimens of the big bluestem (Andropogon gerardiiVitman)—sand bluestem (Andropogon halliiHack.) complex collected from six topographic positions along a local dune to meadow topographic gradient in the eastern Nebraska Sandhills were examined to determine the relationship between morphological variation and habitat variation in adjacent bluestem populations. All morphological characters showed intergradation between big bluestem and sand bluestem but based on awn length, ligule length, cilia length on pedicels and rachises, rhizome length, and hybrid indexes, as well as comparisons with isolated bluestem populations, dune and meadow bluestems were found to be morphologically distinct. Sand bluestem types occupied dry, upland sand dunes, big bluestem types were restricted to adjacent, subirrigated meadows and plants intermediate in morphology were found only in narrow dune/meadow transition zones. For all bluestems, four characters (awn, ligule, cilia and rhizome) were significantly correlated with each other but correlations were most non‐significant when only intermediates were considered; pollen stainability, however, was highly variable and was not related to morphology. Variation in leaf thickness, adaxial stomatal frequency and leaf absorptance to photosynthetically active radiation was found to exist in bluestems, which previously has not been quantitatively described in this complex. Habitat assortment in bluestem types along this dune to meadow topographic gradient was closely related to soil moisture levels which, in these sandy soils, were controlled primarily by the depth of the underlying water table.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08518.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Ants are attracted to extrafloral nectaries subtending reproductive organs ofFerocactus acanthodesvar.lecontei(Cactaceae) in central Arizona. Extrafloral nectar produced by these glands contained amino acids, sugars, and water. Nectar quality and composition varied temporally in relation to plant reproductive phenology. The number of nectar glands on a barrel cactus did not change significantly, however; the mass of nectar produced per gland increased significantly with immature fruit production. Of the three sugars present in extrafloral nectar (fructose, glucose, and sucrose), only glucose occurred at a higher concentration in June, when immature fruits first appeared on barrel cactus. Amino acid concentration and composition in extrafloral nectar of barrel cactus did not change significantly over time. Ant density on barrel cactus increased significantly from mid‐May to mid‐June at two field sites. Water availability per nectar gland increased 158% from May to June. Water plays an important role in attracting ants to barrel cacti.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08519.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Intraseasonal variation in ovule and seed production per flower and per plant of the perennial herbThalictrum thalictroides(L.) Eames and Boivin was documented at three sites during three spring flowering seasons. Shading and pollen‐addition experiments were used to assess the impact of variation in pollination and light availability on seed production. Mean seed number and percent seed set were lower in flowers open late in the season than in those open earlier. The lower percent seed set occurs primarily in flowers that are positioned laterally on the inflorescence and which open later than center flowers. Plants flowering early in the season produce more flowers, ovules and seeds than those flowering later. Mean percent seed set per plant did not change, however, indicating that temporal differences in total seed output can be traced largely to variation in total ovule number. Seed production may be limited by lack of pollination during periods of inclement weather. At least late in the season, seed output may also be resource‐limited: the decline in percent seed set among flowers coincided with the decline in light availability, and hand‐pollination of late‐opening flowers did not increase percent seed set to earlier levels. Artificial shading led to a significant reduction in percent seed set of lateral flowers, and decreased the probability of flowering again the following year. Thus, the relative selective roles of resource and pollination limitations may vary during the flowering season.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08520.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

This paper describes our study of the flavonoid chemistry of the Menyanthaceae, which includedMenyanthes, Fauria(=Nephrophyllidium),Liparophyllum(all monotypic), nine species ofNymphoides,and 11 species ofVillarsia.The flavonoid profiles are based upon kaempferol, 7‐O‐methylkaempferol, quercetin, 7‐O‐methylquercetin, isorhamnetin, 3,7‐di‐O‐methylquercetin, and 7,3′‐di‐O‐methylquercetin, although not all taxa exhibit all of these aglycones. These compounds occur as a complex mixture of 3‐O‐mono‐ and 3‐O‐diglycosides; 4′‐O‐glucosides were restricted to four species ofNymphoides.Some acylated glycosides were also observed. The presence of flavonols and absence of both C‐glycosylflavones and xanthones set the Menyanthaceae apart from the Gentianaceae, the family with which it is most often allied. Flavonoid data do not allow assignment of the Menyanthaceae with surety to either the Gentianales or Solanales. The flavonoid profiles ofLiparophyllumandFauriaare unique within the family and do not support a close affinity of the latter genus toMenyanthes. Aclose relationship betweenNymphoidesandVillarsia,suggested on morphological grounds, is supported by the flavonoid data. Flavonoids support the view, based upon morphology, that the South AfricanVillarsia capensisis more closely related to eastern AustralianVillarsiaspecies than to Western Australian ones that are geographically closer. Segregation ofNymphoides fallaxfrom other Meso‐American and Caribbean taxa is supported by the flavonoid data. Flavonoid data also support the view thatN. indicais a circumtropical taxon not deserving separate species status in the New World.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08521.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

“Individual” large diam lichen thalli ofUmbilicaria vellea(L.) Ach. andU. mammulata(Ach.) Tuck. are not uniform in physiological activity or enzymatic phenotype. Horizontal variation in net photosynthetic rates and dark respiration rates was found, but this was independent of the mass of the photosynthesizing or respiring tissues. In addition, sublethal temperature pretreatments reduced the net photosynthetic and respiratory rates of some areas of the thallus, but increased others.Assays of isoenzyme phenotypes showed that all large diam thalli are extensively polymorphic while young, small diam thalli are mainly monomorphic. Taken together, the results say that the concept of the “individual” may be inappropriate for these organisms.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08522.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Shape variation of 67 specimens from the neotype slide ofTabellaría flocculosawas analyzed by computer‐assisted morphometric techniques. Coefficients of a Legendre polynomial expansion of specimen shapes are shape descriptors used in principal component analysis (PCA). The first PC axis (PC1) is highly correlated with valve length. Variation along PC, is a combination of increase in width with a reduction in the distance between central and terminal inflations. The second axis (PC2) is the major length‐free component of shape variation. Variation in PC2scores is related to the degree of constriction between the poles and the center. Shape variability increases as specimen length decreases. Three nonexclusive hypotheses can explain this: 1) different genetic entities are involved, 2) control of shape is strict in specimens longer than 35 μm, but not for those less than 35 μm, 3) the pattern of variation reflects environmental variation during the period of development of the population.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08523.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

A survey of corolla venation patterns in thePhaceliaHumiles group (Hydrophyllaceae) revealed considerable diversity, ranging from open venation and no interpetal vascular connections in some taxa to closed venation and interpetal vascular connections in others. In general, the distribution of the different venation patterns agrees with recent taxonomic treatments and provides evidence for the artificiality of sections based on ovule number. In several cases where the affinity of a species was ambiguous, the venation pattern of its corollas provides evidence for its placement.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08524.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Seeds ofCakile edentulassp.edentulavar.edentula(hereafteredentula) were collected from the Pacific Ocean shore of Washington, andCakile edentulassp.edentulavar.lacustris(hereafterlacustris) seeds were collected from the Lake Huron shore of Ontario. Germination rates of the two varieties showed equal tolerance of substrate salinities ranging from 0–10,000 ppm. Early root growth ofedentulaseedlings was significantly stimulated by 1,000 ppm salts, but otherwise both varieties showed equal tolerance to 10,000 ppm.Edentulaplants exposed for 4 wk to salt spray intensities of 0, 20, and 90 mg dm–2d–1, applied in a growth chamber environment, showed no significant changes in shoot or root biomass, plant morphology, or reproductive effort.Lacustrisplants exhibited significant declines in stem length and reproductive effort with increasing levels of salt spray. Our results suggest thatlacustrisandedentulahave diverged physiologically over the past 9,000 years, and field observations from the literature corroborate our conclusion that this divergence in salt tolerance has ecological significance.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08525.x

出版商:Wiley    

年代:1986

数据来源: WILEY

摘要:

Callus cultures were established from young vegetative shoots of 15 to 18‐year‐old white pine trees. The callus has been repeatedly subcultured for 15 months on a modified Murashige and Skoog's medium supplemented with 2 mg/L 6‐Benzyladenine and 0.2 mg/L α‐Naphthaleneacetic acid. Best callus proliferation occurred when 2 to 4‐week‐old shoots were used as expiants. Older shoots were heavily contaminated with microorganisms and could be only partially disinfected by heat or chemical treatments.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1986.tb08526.x

出版商:Wiley    

年代:1986

数据来源: WILEY