摘要:

PIKE, L. M., HU, A., RENZAGLIA, K. S.&MUSICH, P. R., 1992. Liverwort genomes display extensive structural variations. Analyses of the total genomic DNA of eight species of liverworts and two species of green algae by thermal denaturation and CsCl buoyant density gradient centrifugation reveal a high degree of structural complexity and interspecific heterogeneity. The hepatic taxa exhibit two or more DNA components of varying base composition. Average G4‐C contents of total cellular DNA calculated from melting profiles are similarly variable, ranging from 38% to 53% G + C. The green algaChara, a member of the ancestral line to land plants, shows similarities with liverworts in possessing multiple DNA components of comparable complexity, whereasHydrodiciyonDNA displays a single component. Detailed hybridization analyses of individual density gradient fractions using α‐tubulin, rRNA and ribulose 1,5‐bisphosphate carboxylase/oxygenase large subunit(rbcL)gene probes were performed to locate the low‐copy number and moderately repetitive nuclear genes, and the chloroplast chromosome, respectively. The location of each gene within the density gradient is highly variable among the organisms examined; a‐tubulin occurs in fractions ranging from 44–64% G + C, rDNA in 50–64% G + C fractions, and theRbcLgene is located in fractions from 30–59% G + C. For a given species, the two nuclear genes normally overlap in their distributions within the gradient. In most instances, neither gene occurs in the major DNA components, indicating that these components may contain repetitive DNAs. The observed variation in the density of therbcLgene implies substantial reorganization of the chloroplast genome. The overall differences in the genomic components within and between taxa provide insight into the dynamics of DNA structure that have occurred during the extended evolutionary history of

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00255.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

TAKASO, T.&TOMUNSON, P. B., 1992. Seed cone and ovule ontogeny inMetasequoia, SequoiaandSequoiadendron(Taxodiaceae–Coniferales). Structural features of seed cones, up to the initiation of ovules, are developed in the three genera in the summer and late fall prior to pollination in the following spring, when cones renew their further development. Bracts are initiated in a decussate manner inMetasequoiabut spirally inSequoiaandSequoiadendron.No ovuliferous scale is initiated, at most there is a shallow mound of tissue on the adaxial surface of the bract from which the ovules are developed.Metasequoiaproduces a single series of up to eight ovules in acropetal (centripetal order),SequoiaandSequoiadendronproduce a double series of six to nine ovules, also in acropetal order, since a second series of ovules appear distal to and alternate with the first series. Common features that unite the genera are the somewhat peltate configuration of the cone scales due to late intercalary expansion, the derivation of the vascular supply to the bract‐ovule complex from a single bundle and the usual inversion of the seed during late development, to which can be added developmental features. The absence of tooth‐like structures, present in some other Taxodiaceae, is discussed in relation to cone evolution in the family being determined by changes in developmental timing. Emphasis is made on the way in which features of morphogenesis, determine cone organization in the three genera independent of an interpretation that relies solely on hypothetical ancestral

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00256.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

BOSCH, J., 1992. Floral biology and pollinators of three co‐occurringCistusspecies (Cistaceae). The pollination of three speciesof Cistus, Cistus albidusL.,Cistus salvifoliusL. andCistus monspeliensisL. is studied. Insect visitors were censused and some were captured to analyse pollen distribution on their bodies. Floral phenology, breeding systems, some aspects of floral biology (pollen and nectar production, pollen‐ovule ratios) and floral morphology were also studied for each species. Flowers ofC. albidusproduce more pollen and nectar than the other two species studied, and attract more insects, especially those with higher nutritional requirements. All three species are highly self‐incompatible, butC. salvifoliusandC. monspeliensisshow some features that hinder xenogamy, and they have lower pollen‐ovule ratios thanC. albidus.As a result, this latter species apparently receives higher levels of cross‐pollination, but at the cost of a higher investment to attract and reward reliable po

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00257.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AGUINAGALDE, I., GOMEZ‐CAMPO, C.&SANCHEZ‐YELAMO, M. D., 1992. A chemosystematic survey on wild relatives ofBrassica oleraceaL. A study on 12 taxa ofn= 9, wildBrassicaspecies (including wildB. oleracea)has led to the detection of 21 different flavonol‐glycosides. Differential patterns have been obtained for each taxon. Seed proteins and five isoenzyme systems have been analysed by polyacrylamide gel electrophoresis. The presence of many bands common to ail species was the rule for seed proteins, but differences in polypeptide contents were observed. There were also clear qualitative differences in isoenzyme patterns. Interspecific differences were examined by including those phytochemical characters in a numerical analysis. While the maximum morphological variability occurs in Sicily, phytochemical diversity seems to be maximum further east, in theB. cretica

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00258.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

PERIS, J. B., STÜBING, G.&FIGUEROLA, R., 1992. A new species ofSideritisL. (Lamiaceae) for the Spanish flora. A description is given of a new species of the genusSideritisL. for the Spanish Flora

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00259.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

WIKLUND, A., 1992. The genusCynaraL. (Asteraceae‐Cardueae). This study includes a taxonomic revision of the genusCynara.Eight species and four subspecies are recognized, viz.C. algarbiensis, C. auranitica, C. baeticaincluding subsp.baeticaand subsp.maroccana(formerly known asC. hystrix), C. cardunculusincluding subsp.cardunculusand subsp.flavescens, C. cornigera, C. cyrenaica, C. humilis(formerly sometimes in the genusBourgaea)andC. syriaca.The cultivated artichoke (formerlyC. scolymus)and cardoon are both included inC. cardunculus.One species,C. tournefortii, is excluded fromCynara.A cladistic study of the genus is also undertaken and its morphology, anatomy and phytogeography are discusse

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00260.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

VALDÉS, B.&DÍAZ LIFANTE, Z., 1992. Karyology and reproductive biology ofMuscari matritensisM. Ruíz Rejónet al.(Liliaceae).Muscari matritensisM. Ruíz Rejónet al., previously known from only five localities, has been recorded for S.W. Spain. The plants have a karyotype composition which differs from the other four karyotypes described for this species, and experimental studies of the breeding system provide evidence that they are moderately autog

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00261.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

VAN RAAMSDONK, L. W. D.&DE VRIES, T. 1992. Biosystematic studies inAlliumL. sectionCepa.Principal component analyses and hybrid analyses, according to Wells, using 31 morphological characteristics were used to study the biosystematic relationships between sixAlliumspecies of sectionCepaandA. royleiof sectionRhizirideum.Seventeen interspecific hybrid populations were included. Based on these analyses and on additional information from geography, chromosome banding pattern, DNA amount and seed epidermis texture, the speciesof AlliumsectionCepacan be divided into three groups: 1.A. galanthumandA. pskemense, 2.A. cepa, A. oschaniniiandA. vaviloviiand 3.A. futulosumandA, allaicum.Presumed evolution of both groups 2 and 3 from the basic group 1 is indicated by the development of new morphological characteristics, a change in genome structure and migration.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00262.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

NILSSON, L. A., RABAKONANDRIANINA, E., RAZANANAIVO, R.&RANDRIAMANINDRY, J.J., 1992. Long pollinia on eyes: hawk‐moth pollination ofCynorkis unifloraLindley (Orchidaceae) in Madagascar. The pollination biology ofCynorkis unifloraLindley (Orchidaceae) was studied on a rocky outcrop in a fragment of montane rain forest in central Madagascar. The plant was obligately pollinated by hawk‐moths. Nectar was produced in a floral spur and was accessible to hawk‐moths with medium‐long and long tongues. All observed visits took place during the 80 min following dusk. Floral traits and visits indicated pollination association with endemic hawk‐moths of the generaNepheteandHippotionwith medium tongue length and early‐evening habits. The orchid pollinia had extraordinarily long caudicles(c.16 mm) and were carried attached to the hawk‐moths' eyes, thus protruding far in front of the face of the pollinator. The ratio between components of floral female and male functions within the orchid population suggested that the much elongated operative male floral parts result from strong and progressively extreme sex‐specific selection for acquiring mates via hawk‐moths. By far the most frequent flower‐visitors ofC. unifloraat the study site were long‐tongued nectar thieving hawk‐moths whose relative abundance probably reflected faunal imbalance caused by the destruction of nearby moth foraging habitat

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00263.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1992.tb00255a.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY