摘要:

Starch gel electrophoresis of plant proteins was used to identify purple loosestrife (Lythrumspp.) cultivars and weedy populations. Preliminary determinations were made as to what degree weedy loosestrife populations were related (or genetically similar) to populations ofL. alatum, L. virgatum, and horticultural cultivars. Cluster analysis of the data indicated that nativeL. alatumwas genetically different from all populations of purple loosestrife and cultivars examined. TheL. salicariaandL. virgatumcultivars, as groups, were not genetically distinguishable from the weedy populations analyzed. Seven cultivars ofL. salicariaorigin analyzed as a group were not distinguishable from the eight cultivars ofL. virgatumorigin, indicating that separation by cultivar origin may not be feasible. While the two “groups” were not distinguishable, most individual cultivars could be distinguished from one another by isozyme phenotype. Genetic variation was high within populations of weedy purple loosestrife but low among populations, which is characteristic of polyploid, perennial plant species that are widely distributed. Geographic location did not consistently correlate with genetic similarity.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12707.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

A comparison of cellulose synthesized in vitro from primary walls of etiolated mung bean (Vigna radiata) seedlings and secondary walls of cotton fibers (Gossypium hirsutum) was made by applying conditions found to be essential for in vitro cellulose I assembly from cotton (Kudlicka et al., 1995,Plant Physiology, vol. 107, pp. 111–123). Mung bean fractions including the plasma membrane (PM), the first solubilized fraction (SE1), and the second solubilized fraction (SE2), incorporated more radioactive UDP‐Glc into the total product than the same fractions from secondary walls. A significant difference was found with the mild digitonin solubilized fraction (SE1), which produced eight times more total product than the SE1fraction of cotton. However, the SE1fraction from cotton produced a larger quantity of cellulose (32.1%) than from mung bean (6.9%). Treatment of the in vitro product by acetic/nitric acid reagent (AN) for varying periods of time demonstrated that cellulose synthesized in vitro from mung bean was more easily degraded than cellulose from cotton fibers. This would suggest that cellulose I produced in vitro from the cotton SE1fraction may have a higher crystallinity and DP than cellulose I produced in vitro from mung bean. The fibrils of cellulose produced by the SE, fraction of mung bean were loosely associated and not arranged into a compact bundle as in case of cellulose I synthesized by the cotton SE1fraction. The electron diffraction patterns (ED) of both products show reflections characteristic for cellulose I. Products from the SE2fraction of mung bean and cotton reveal similarities with the cellulose II allomorph synthesized, as well as abundant β‐1,3‐glucan.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12708.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

The tobacco stamen has been the object of many developmental studies, and the organ has more recently become a model for molecular genetic studies of anther differentiation. However, the spatial and temporal details of cellular differentiation of early anther development have never been thoroughly characterized. In the present study, the age of 15 tobacco flowers from plants grown under constant light and temperature was estimated using growth analysis. Prior to tissue fixation for light microscopy, moulds of stamen and anther primordia were made with a dental impression polymer so morphological and histological observations could be made on each tissue sample. Flower ages spanned an 8‐d interval during which petal and stamen initiation occurred, and sporogenous cells reached the leptonema stage of meiosis. The initial development of the tetrasporangiate anther shape largely preceded periclinal division of archesporial initials. Anatomically, periclinal divisions in the hypodermal ∗∗∗(l2) layer were observed before archesporial initials began to divide. These data indicate differences in the cellular basis of tobacco anther development compared to earlier clonal analyses ofDatura.The pattern of mitotic cell division associated with microsporangial development suggested modal peaks in division over time. The ability to estimate developmental time in the tobacco anther has implications for future studies directed at understanding mechanisms of anther evolution via heterochrony.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12709.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

We sampled 17 populations of a rare autotetraploidAster kantoensis(Asteraceae) from three river systems located in central Japan, and studied them for allelic variation at 22 enzyme loci. There was no significant correlation between the actual population size and three genetic diversity parameters, suggesting that the effective population size was very small even for the large populations, i.e., even large populations may still have a high probability of being of recent origin and remain influenced by the founder effect. Compared to other autotetraploid species, the total genetic variation ofA. kantoensisis small. The number of alleles and gene diversity of a population were not significantly different among the river systems, although the percentage of polymorphic loci was different. Genetic differentiation among river systems was larger than between populations within the river systems, thereby indicating that gene flow between river systems is small, especially between the Kinu River system and Tama or Sagami River systems.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12710.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

I describe temporal patterns of seed production in the andromonoecious lilyZigadenus particulatus.Fruit set per flower and seed set per fruit declined through time within plants. Hand pollination experiments showed that this was not due to increasing pollen limitation. Nutrient supplementation had little effect on seed output, but leaf clipping reduced seed production, especially in late‐blooming flowers, and removal of early‐blooming flowers increased seed set by later flowers. Thus, the temporal pattern of seed output was due to declining availability of photosynthates. Plants with larger bulbs produced larger inflorescences, a greater proportion of hermaphrodite flowers, more fruits per hermaphrodite flower, and more seeds per fruit, but lost a greater fraction of their initial bulb mass as a consequence of fruiting. After controlling for the effects of bulb mass, plants with larger inflorescences produced a greater proportion of male flowers, and plants with more hermaphrodite flowers produced fewer fruits per hermaphrodite flower and fewer seeds per fruit. Thus, the female fitness gain curve was decelerating. The temporal decline in seed output provides a partial explanation for the parallel decline in allocation to pistils. However, a complete explanation for the pattern of gamete packaging requires an understanding of factors controlling male, as well as female, fitness.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12711.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

We investigated the fates of ovules following self‐ and cross‐pollination of the variably self‐sterileEpilobium obcordatumby observing thin sections of ovaries 4, 5, and 10 d postpollination (PP). Three types of unfertilized ovules were observed: apparently normal ovules not entered by pollen tubes, nonfunctional ovules with a nucellus but lacking an embryo sac, and empty ovules with integuments but lacking a nucellus. The average frequencies for all three types were not different for selfs and crosses. Fertilization frequencies did not differ among pollination treatments, averaging 61.4% of the total sample of 4 and 5 d PP ovules. The phenotypes of failing postfertilization ovules at 4 and 5 d PP included those containing preglobular and globular embryos lacking endosperm, ovules with endosperm but no embryo present, and failing embryos in the presence of endosperm. Self‐ and cross‐fertilized 10 d PP ovules also possessed heart‐stage and torpedo‐stage failing embryos. Early embryo failures (5 d PP) were distributed throughout the length of the ovary, as expected if failures are the consequence of factors intrinsic to each ovule. The sizes of normally developing self‐ and cross‐fertilized embryos were not different at 4 d PP. The 5 d PP cross embryos were larger than selfs. A comparison of 10 d samples was not possible due to attrition of self embryos. Although ovular position did not affect the probability of early embryo failure, it did affect the size of normally developing embryos at 4, 5, and 10 d PP, with embryos at the stylar end larger than those at the basal end.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12712.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

Delayed outcrossed pollination of female spinach plants (Spinacea oleraceaL.) resulted in increased stigma length and a male‐biased progeny sex ratio. One group of females was outcrossed 10–14 d after anthesis, a second group was never outcrossed, and a third group, the control, consisted of females that were outcrossed as soon as stigmas appeared. Stigma length was significantly greater for plants in the delayed and never outcrossed groups compared to the control. Furthermore, stigmas of virgin flowers grew until they were either pollinated or the plants produced anthers. Plants that were never outcrossed produced their own anthers and self pollinated. The resulting progeny were all female. The sons of the delayed outcrossed group produced more stamens, on average, than sons of the control group.The observed male‐biased sex ratio among the progeny of delayed outcrossed plants could be due to gametic selection. To test for this, plants were held virgin until their stigmas reached a length of at least 3 mm. These stigmas were then pollinated either distally or proximally. No significant difference was found between the progeny sex ratios of these two treatments. However, both sex ratios were more male biased than progeny of plants pollinated the day of anthesis (control group of the first experiment). We conclude that maternal factors, rather than gametophytic selection, may be responsible for the male‐biased sex ratio observed in the first experiment.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12713.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

An experiment was conducted to determine if spatial nutrient heterogeneity affects mean plant size or size hierarchies in experimental populations of the weedy annualAbutilon theophrastiMedic. (Malvaceae). Heterogeneity was imposed by alternating 8 × 8 × 10 cm blocks of low and high nutrient soil in a checkerboard design, while a homogeneous soil treatment consisted of a spatially uniform mixture of the two soil types (mixed soil). Populations were planted at three densities. The effect of soil type on the growth of individuals was determined through a bioassay experiment using potted plants. The high nutrient, low nutrient, and mixed soil differed in their ability to support plant growth as indicated by differences in growth rates and final aboveground biomass. Concentrations of N, K, P, and Mg, measured at the end of the growing season in the experimental plots, also differed among all three soil types. Nevertheless, nutrient heterogeneity had little effect at the population level. Mean maximum leaf width measured at midseason was greater for populations on heterogeneous soil, but soil treatment did not affect midseason measurements of plant height, total number of leaves per plant, or canopy width. Population density affected all these parameters except plant height. When aboveground biomass was harvested at the end of the growing season, soil treatment was found to have no main effect on mean plant biomass, total population biomass, the coefficient of variation in plant biomass, or the combined biomass of the five largest plants in the population, but mean plant biomass was greater for populations on heterogeneous soils at the intermediate planting density. Mean plant biomass, total population biomass, and the coefficient of variation in plant biomass all varied with planting density. Mortality was low overall but significantly higher on homogeneous soil across all three densities. Soil heterogeneity had its strongest effect on individuals. In heterogeneous treatments plant size depended on the location of the plant stem with respect to high and low nutrient patches. Thus, soil nutrient heterogeneity influenced whether particular individuals were destined to be dominant or subordinate within the population but had little effect on overall population structure.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12714.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

Various hypotheses have been put forward to explain the presence of sclerophyllous plant disjuncts between western North America and the Mediterranean region. The Madrean–Tethyan hypothesis postulates that the two regions were floristically connected in the Early to Middle Tertiary by way of a low‐latitude migration route. Others deny the possibility of such a route, and instead postulate convergence to xerophytic conditions from more widespread mesophytic ancestors, or suggest long‐distance dispersal scenarios. One example of a “Madrean–Tethyan link” between the two regions is composed of four species within the genusStyrax: S. officinalissubsp.officinalisfrom the Mediterranean region,S. officinalissubsp.redivivusand subsp.fulvescensfrom California, and three closely related species in Texas and northeastern Mexico (S. texanus, S. platanifolius, andS. youngiae). This group was examined with isozymes to assess whether patterns of genetic variation are consistent with those predicted by the Madrean–Tethyan hypothesis. Ten populations from California, six from the Mediterranean region, and three from Texas were sampled. Pairwise comparisons revealed mean genetic identity (I) estimates of 0.581 between Mediterranean and California populations, 0.470 between Mediterranean and Texas populations, and 0.640 between California and Texas populations. Two populations of a species thought by many to be the closest relative ofS. officinalison morphological grounds (S. jaliscanus) exhibited lowI(0.299–0.321) relative to all other group comparisons. Intercontinentally disjunct populations ofS. officinalispossessed anIvalue that warrants species status for the Californian and Mediterranean groups. Divergence time estimates between Madrean and TethyanStyraxrange from 5.0 to 13.8 Mya, too recent to be consistent with the Madrean–Tethyan hypothesis. However, alternative explanations for this disjunction are suboptimal in that they require the invocation of either long‐distance dispersal, which appears unlikely in this group, or extinction. Nonetheless, the evidence presented here and in other recent studies casts substantial doubt on the Madrean–Tethyan hypothesis as a general explanation for the presence of Madrean and Tethyan taxa similar in overall appearance. More plants with Madrean–Tethyan distributions must be sampled before definitive conclusions regarding this aspect of Madrean and Tethyan vegetation can be reached.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12715.x

出版商:Wiley    

年代:1996

数据来源: WILEY

摘要:

RayjacksoniaR. L. Hartman&M. A. Lane, gen. nov. (Compositae: Astereae), is named to accommodate the “phyllocephalus complex,” formerly ofHaplopappusCass. sect.BlepharodonDC. The new combinations areR. phyllocephalus(DC.) R. L. Hartman&M. A. Lane,R. annua(Rydb.) R. L. Hartman&M. A. Lane, andR. aurea(A. Gray) R. L. Hartman&M. A. Lane. This transfer completes the reclassification of the North American species ofHaplopappussensu Hall, leaving that genus exclusively South American.Rayjacksoniahas a base chromosome number ofx =6. Furthermore, it shares abruptly ampliate disk corollas, deltate disk style‐branch appendages, and corolla epidermal cell type, among other features, withGrindelia, Isocoma, Olivaea, Prionopsis, Stephanodoria, andXanthocephalum.Phylogenetic analyses of morphological and chloroplast DNA restriction site data, taken together, demonstrate that these genera are closely related but distinct.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1996.tb12716.x

出版商:Wiley    

年代:1996

数据来源: WILEY