摘要:

Genetic variation in life history traits has important consequences for life‐history evolution. Here we report the results of a greenhouse experiment investigating the broad sense genetic basis of variation in life history traits within and among five populations ofCampanula americanadistributed along a latitudinal gradient. The populations exhibit differentiation for a number of morphological traits (seed weight, number of branches, final plant size, number of capsules) and the phenological traits, days to emergence, days to bolting, the onset of flowering, and the duration of flowering. Families within populations differed only in days to emergence and seed weight. These results suggest that the life history differences among populations are genetically based. In addition, two life history types—winter annuals and biennials—have previously been reported from natural populations ofCampanula americana.This experiment identified a third type—summer annuals from the Florida population.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15480.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Linum perenneL. is a nonclonal perennial herb widely distributed across a range of habitats. Variation in seed germination patterns was examined for 21 Intermountain collections and for the commercial cultivar ‘Appar’. Collections from sites with long, snowy winters were largely dormant at harvest and responded positively to chilling. Collections from middle elevation sagebrush‐grassland sites were generally nondormant and contained a fraction induced into secondary dormancy by chilling. Collections from palouse prairie and pinyon‐juniper sites were generally nondormant and unaffected by chilling, as was ‘Appar’. When seeds of contrasting populations were planted in seed retrieval experiments at low, middle, and high elevation sites, their field germination phenology was predictable from laboratory experiments. In common garden experiments, there were significant among‐sibship differences in germination for each garden‐grown wild accession but not for ‘Appar’, suggesting that differences both among and within populations may be genetically based. Garden‐grown seeds were generally less dormant than wild‐collected seeds, possibly because of selection during propagation. Results demonstrated the existence of ecologically relevant among‐population and within‐population variation in germination phenology for blue flax. Seeds of high‐montane populations are spring‐emerging and have little provision for between‐year carryover. Populations from lower elevation habitats with less predictable weather have seeds with contrasting germination patterns, allowing for emergence in both fall and spring as well as for seed bank carryover. ‘Appar’ seeds lack these predictive and carryover mechanisms.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15481.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

In a 3‐yr field studyAmmophila breviligulataresponded positively to sand accretion by maintaining plant height above a rising sand surface. Vertical growth for treated plants was approximately 80 cm over 3 yr. Bunch size did not differ between treated and control plants in the first or second year. But by Year 3, bunch circumference, number of stems per bunch, and plant height above the sand surface were significantly greater in plants receiving accelerated sand accretion. During the first year, treated plants flowered significantly less than controls. The greater vertical growth necessary for the treated plants may have depleted the energy reserves of a young rhizome system otherwise used for inflorescence production. The percent of the total nonstructural carbohydrates in rhizomes in the form of sugar was greater in plants in the accelerated sand accretion treatment, perhaps sustaining the necessary rapid vertical growth. To determine whether ethylene plays a role in stimulating stem elongation, endogenous ethylene accumulation was measured in plants in the field and seedlings in the greenhouse exposed to sand accretion. Treated plants responded by accumulating higher levels of ethylene in their stems, after 10 and/or 30 d, than did control plants. However, plants treated with exogenous ethylene exhibited growth and elongation inhibition.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15482.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Investigations of the floral biology of the traveler's tree (Ravenala madagascariensis) and the ecology of the ruffed lemur (Varecia variegata), both endemic to the island of Madagascar, suggest a plant‐pollinator relationship.Ravenalaexhibits many specializations for visitation by large nonflying animals: inflorescences placed below the crown of the plant and easily accessible to arboreal animals; large flowers enclosed in tough, protective bracts that require a strong pollinator to open; stiff, rodlike styles that withstand the rough handling of the visitors; and copious, sucrose‐dominant nectar that provides a renewable reward for a sizable animal for a long time period. Our observations in the field also show thatVarecia variegata:consistently and almost exclusively visit the flowers ofRavenala; carry pollen on their fur between flowers on the same plant and between conspecific plants; do not destroy the flowers while obtaining the nectar; and appear to be highly dependent on nectar as a food source during specific times of the year. The basal phylogenetic position ofRavenalain the family Strelitziaceae, as indicated by molecular sequence data, and the distribution of reproductive traits in the three extant genera are consistent with the hypothesis that pollination by nonflying mammals is an archaic system, whereas bird and bat pollination are derived.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15483.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Pollen development requires a large number of genes expressed in both sporophytic and gametophytic tissues. We have isolated a pollen‐specific gene,PS1, from rice.PS1is a unique gene in the rice genome and encodes a 164 amino acid long protein. RNA blot analysis shows thatPS1mRNAs accumulate specifically in rice anthers. When introduced into rice tissues by microprojectile bombardment, thePS1promoter drives expression of a marker gene, β‐glucuronidase, specifically in rice pollen. ThePS1gene and the deduced amino acid sequence of the PS1 protein share significant levels of homology with another monocot pollen‐specific gene—the maizeZm‐13gene and its deduced protein, respectively.PS1also shows some homology with the dicot tomato anther‐specific geneLAT‐52.Interestingly, the structure of thePS1gene is more similar to that of theLAT‐52gene than toZm‐13.The coding regions of bothPS1andLAT‐52are interrupted by a single intron, and the positions of the introns are conserved in these genes. Moreover, there is considerable sequence homology in the introns of thePS1andLAT‐52genes in regions immediately upstream of the 3' splice sites. The upstream regulatory sequences of thePS1gene show several regions of homology with other pollen‐ or anther‐specific genes from a number of plant species. The conservation of coding sequences ofPS1from rice,Zm‐I3from maize, andLAT‐52from tomato suggests a functional conservation of their gene products. Similarities in the regulatory regions ofPS1and other anther‐ or pollen‐specific genes among monocotyledonous and dicotyledonous species indicate that at least some regulatory features controlling gene expression in male reproductive tissues are conserved. This is supported by the preservation of pollen‐specific expression from the ricePS1promoter when it is introduced into tobacco plants byAgrobacteriumTi plasmid‐mediated transformation.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15484.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Seasonal changes in the development of reproductive structures are documented forPopulus trichocarpaTorr. and Gray. Buds were collected and studied from several trees for a 2‐yr period, but to maintain a congruous phenology, representative structures from only one male and one female tree are presented. Collected tissues were fixed, dehydrated, embedded in wax, sectioned, and differentially stained. The development of reproductive meristems begins early in the spring, before leaves emerge. However, the anatomy of male and female flowers is virtually indistinguishable until late spring. The structures of the gynoecium develop in about 2 wk, then continue to enlarge through the summer and autumn until the trees become dormant. The unilocular ovary consists of usually three, but sometimes four carples. Stamen development begins in the center of a disk‐shaped meristematic region and proceeds centrifugally. Megasporogenesis and microsporogenesis take place late in the winter, approximately 2 wk before anthesis. Dissection of mature flowers revealed 30–50 seeds per capsule on female trees and 40–60 stamens on male trees. When compared to most otherPopulusspecies,P. trichocarpahas a relatively large number of reproductive structures.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15485.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

One hypothesis for the evolution of maleness in plants postulates the following: male plants appear that have re‐allocated resources from female parts into a larger number of male flowers, creating a larger floral display. Pollinators respond “dramatically” to the increased display, driving the spread of males in the population (Bawa, K. S., 1980,Annual Review of Ecology and Systematics11:15–40). To test this, we measured the total number of flowers and the size of male displays in dioeciousSagittaria latifoliaand monoeciousS. australis.We also measured how fast visitors arrived at “target” flowers in the displays. Then we used the Cox Model, a failure time analysis procedure, to analyze the relationship between visitor arrival and display size. We found that male display sizes were somewhat larger in the dioecious than the monoecious plants, but this was due to more compressed blooming rather than to a larger total number of flowers. The visitors to both plants were similar arrays of generalist bees. Visitors did not show the predicted “dramatic” response, however, but rather a plateauing response to larger display sizes, so our results do not support the hypothesis. Reviewing the literature, we found no reports of the “dramatic” response the hypothesis asserts. Instead, relative insensitivity to display size is the rule.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15486.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Flowers of 169 species of Rosaceae subfamily Maloideae, which were chosen to represent the taxonomic and geographic diversity of the group, were studied to ascertain their morphological variation and its systematic relevance. We describe and illustrate variation in size, indumentum, color, and macroscopic structural features. Most maloid species have syncarpous flowers with two to five carpels in which the ovary is at least three‐quarters inferior, whereas species of other Rosaceae subfamilies have apocarpous or unicarpellate flowers with superior ovaries. However, maloid flowers show significant variation in the degree of carpel connation and of ovary adnation to the hypanthium.Cotoneaster, Heteromeles, andPyracanthaare completely apocarpous, andDichotomanthesis perigynous with a completely superior ovary. Thus, no one floral character is sufficient to separate the Maloideae from other subfamilies of Rosaceae. Differences among their flowers support our recognition ofMalus, Pyrus, andSorbusas separate genera. Further, we argue for removal ofDocyniopsisandEriolobusfromMalus, division ofSorbusinto several genera, and union ofAronia, Photinia, andStranvaesia.No floral characters support the traditional dichotomy of the subfamily into tribes Crataegeae and Sorbeae.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15487.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

We characterized the development of a tobacco morphological mutant,puzzle box, previously obtained by selection for resistance to an inhibitor of an enzyme in the polyamine biosynthetic pathway.Puzzle boxplants are shorter than wild type with smaller leaves and an irregular leaf plastochron. The diameter and shape of thepuzzle boxshoot apex are similar to wild type. Inpuzzle boxplants, the terminal flower develops but not the cymose inflorescence. This flower has a variable phenotype with more than five sepals, five petals, and five stamens. The organs in the fourth whorl are produced by carpellike primordia and contain tissue biochemically similar to wild type transmitting tissue. These organs form a cylinder within which additional floral organs are produced. Some cultures ofpuzzle boxbuds and excised cylinders produce additional floral organs. The inflorescence and floral programs may be expressed together inpuzzle box.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15488.x

出版商:Wiley    

年代:1994

数据来源: WILEY

摘要:

Physiological and anatomical attributes of leaves were examined of three species ofQuercussectionErythrobalanus.All three species occur in moist temperate deciduous forests of eastern North America. Seedlings of each species were grown in different light conditions for comparison. The attributes measured were net photosynthesis, stomatal conductivity, blade and cuticle thickness, stomatal density, thickness of upper and lower epidermis, and thickness of palisade mesophyll. The results generally demonstrate the close association between anatomical adaptations and efficiency of physiological processes; they also elucidate the distribution patterns of the threeQuercusspecies across the forest topography in southern New England. The most drought‐tolerant and light‐demanding species,Q. velutina(Lam.), exhibited the greatest leaf anatomical plasticity, the highest net photosynthesis in the different light conditions, and the lowest stomatal area per unit area of leaf. The most drought‐intolerant species,Q. rubra(L.), exhibited the least leaf anatomical plasticity, the lowest net photosynthesis in the different light conditions, and the highest stomatal area per unit area of leaf.Quercus coccinea(Muenchh.) usually exhibited values that were intermediate betweenQ. rubraandQ. velutina.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1994.tb15489.x

出版商:Wiley    

年代:1994

数据来源: WILEY