摘要:

Because of the unique developmental features of higher plants, somatic mutations may enter the germline and be transmitted to the progeny. In the present review, the role of somatic mutations in higher plant evolution is documented by taking into account the following topics: somatic gene mutations and chromosome structural changes; aneusomaty; bud sports; periclinal chimeras; somatic chromosome doubling; virus infection; effects of environment and soil conditions; mutagenic plant products.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797380

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

A B-chromosome system has been found inRanunculus bulbosus.87 plants from Monte Croce della Serra in Umbria (Italy) have been examined and 12 of these have shown Bs. Bs inR. bulbosusare unstable (in roots, leaves and male meiocytes), very small (less than 1 μm), can reach relatively high numbers (up to 19B) and are heterochromatic (visible in interphase nuclei after Feulgen or Giemsa staining procedures). In spite of the wide intra tissue range of B number the mitotic behaviour of B is very often regular. Also microsporogenesis observations have shown that Bs can pair and segregate regularly in the A chromosome fashion, especially when the B-number in meiocytes is low. Irregularities (clumps, laggards, micronuclei) are much more frequent when Bs are more than six.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797381

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797382

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

A cyto-histological study was carried out onPinus sylvestrisseedlings artificially infected with basidiospores ofMelampsora pinitorquaandMelampsora larici- tremulae, in order to differentiate between the two rust fungi and delineate their taxonomical relationships. The general morphology of the early phases of the majority of infections ofMelampsora larici-tremulaeonP. sylvestrisshow similar characteristics to those ofM. pinitorqua.Moreover, inM. larici-tremulae/P. sylvestrisinteractions, the following were the specific characteristics: abnormal germlings and secondary basidiospore production, «cell wall-like appositions» encasing the fungal structures in the host, necrosis of the infection structures, necrosis of the host tissue colonized by mycelium from epidermal to parenchymal cells. Such reaction types reveal the coexistence of pre-and posthaustorial defence mechanisms, typical, respectively, of a non-host and host resistance. This coexistence which is useful in understanding the evolution of this host-rust interaction, was examined. The described defence mechanisms ofP. sylvestrisvs.M. larici-tremulaecould indicate that the two rust fungi are still closely related entities, however diverging, which evolve from «formae speciales» to «species».

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797383

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

Peripheral blood cultures were set up to obtain high resolution GBA + CBA banding in cattle prometaphase chromosomes of normal karyotypes and rob (1; 29) carrying karyotypes by using early BrdU incorporation simultaneous to MTX-block, Fifty-nine karyotypes were strictly arranged according to the Reading Conference standard. Chromosome pairs from 24 to 29 were also shown in their RBA- banding paterns to further support the GBA + CBA banding in the same chromosomes, including the most disputed ones (chromosomes 25, 27, 28 and 29), and the inconsistencies in the two international cattle chromosome nomenclatures. Comparisons with cattle and river buffalo standard nomenclatures are reported. This study is our contribution to the construction of a GBA + CBA standard karyotype in cattle.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797384

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

The use of heterochromatic regions, containing moderately repetitive DNA as markers, has allowed to follow the course of development of the generative and vegetative nuclei in the pollen grains of some species ofTradescantiaandNarcissus.It has been found that the chromocentres, relatives to the NOR-heterochromatin, are not randomly distributed. This implies the existence of a special mechanism governing the orientation of the centromeres in the spindle-shaped generative nuclei: a predisposition which may facilitate the mitotic process in the pollen tube.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797385

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

The present paper deals with chromosome number of eightAlchemillaL. species from the section Alchemilla Rothm., subsection Chirophyllum Rothm., ser. Sericeae Bus. and subsection Heliodrosium Rothm., ser. Pubescentes Bus. The studies were carried out on plants from the Northeast Anatolia (Turkey). The following chromosome numbers have been detected:A. sericeaWilld. 2n= 104,A. rizensisPawl. 2n= 74–98,A. sericataReichb. 2n= 92–95,A. caucasicaBus. 2n= 96–104,A. erythropodaJuz. 2n= 96–101,A. surculosaFröhn. 2n= 80–92,A. plicatissimaFröhn. 2n= 104–106,A. lithophilaJuz. 2n= 64–88. The species of genusAlchemillaL. studied from Northeast Anatolia are proven to be polyploids like the majority of species from the section Alchemilla investigated from various geographic areas.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797386

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

The karyotype of swamp minnow,Eupallasella percnurus(=Phoxinus percnurus) from northern part of Poland was studied by conventional Giemsa staining and Ag-NOR technique. The diploid chromosome number 2n= 50, was composed of 5 pairs of metacentric, 15 pairs of submetacentric and 5 pairs of subtelo- to acrocentric chromosomes (NF = 90). Two pairs of NORs bearing chromosome were detected. They were located terminally on the short arms of one pair of medium sized submetacentric and on one pair of medium sized subtelocentric chromosomes. Most of the related species from the genusPhoxinusandMorocohad diploid chromosome number 2n= 50 and their karyotypes were also characterized by the biggest acrocentric pair. Most of the North American minnows species had one pair of NORs bearing chromosomes.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797387

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor

摘要:

Cell lines were established from three sturgeon species. All were maintained for more than 15 subcultures. The cytogenetic characterization of the three lines yielded the following results:Acipenser baeri2n= 246±10,Huso huso2n= 120±8, andAcipenser transmontanus 2n= 246±10.

ISSN:0008-7114    

DOI:10.1080/00087114.1997.10797388

出版商:Taylor & Francis    

年代:1997

数据来源: Taylor