Karyotype of Mesembryanthemum crystallinum (Aizoaceae) studied by chromosome banding,FISH with rDNA probes and immunofluorescence detection of DNA methylation

The karyotype of the common ice plant Mesembryanthemum crystallinum L. (Aizoaceae) was studied using Chromomycin A₃ (CMA)/4′,6-diamidino-2-phenylindole (DAPI) staining, fluorescence in situ hybridization with 5S and 18S–5.8S–25S rDNA probes, DAPI/C-banding and immunodetection of 5-methylcytosine. A single bright CMA-band was revealed on the satellite chromosome, whose location was coincided with a position of a site of 18S–5.8S–25S rRNA genes. A site of 5S rRNA genes was observed on one of the other chromosomes. Relatively large DAPI/C-bands were mainly localized in the pericentromeric regions of the chromosomes. DAPI/C-banding patterns allowed us to identify all the chromosomes in the karyotype of M. crystallinum. The methylation of euchromatic chromosome regions was weaker as compared with heterochromatic DAPI/C-bands, which were hypermethylated. The obtained results may provide opportunities for investigating, at the chromosomal level, the genomic changes occurring in M. crystallinum either under salinization or under the action of other stress factors.     

体外培养的绒毛细胞中普通脆点的研究

体外培养绒毛细胞,用缺叶酸培养基或在培养基中加入大量鸟苷或胸苷,造成脱氧核苷酸库的不平衡,导致染色体断裂和普通脆点的表达。大量鸟苷对普通脆点的诱导作用较强,而大量胸苷的作用则稍缓和。大量鸟苷与缺叶酸培养基合并使用时,诱导作用减弱,其可能原因是:缺乏叶酸使鸟苷生成受阻,脱氧核苷酸库的不平衡状态减轻。     

夏蜡梅属的细胞地理学研究

本文首次报道西美蜡梅(Calycanthus occidentalis)的核型为K(2n)=22=20m(2SAT)+2sm,与美国蜡梅的变种光叶红(C.floridus var.oblongifolius)同属“2A”类型但较为原始,它们都比“1A”的夏蜡梅(C.chinensis)进化,三者由原始到进步的顺序可能为夏蜡梅—→西美蜡梅—→美国蜡梅(光叶红)。夏蜡梅属可能以较原始的夏蜡梅起源于东亚(中国),再东向迁移到北美洲(美国)形成西美蜡梅和美国蜡梅(光叶红)。     

A survey of C-band patterns in chromosomes ofLilium (Liliaceae)

C-band patterns are described for 20Lilium spp. distributed across six sections. All species have a similar basic karyotype (n = 12) but C-bands differ markedly between them. The patterns are characterized by a dispersed scattering of thin intercalary bands as well as centric and NOR bands. Only one species,L. canadense, shows a clear equilocal pattern with intercalary C-bands occurring proximally in all of the longer chromosome arms. Comparing species, similar patterns are revealed forL. regale andL. sulphureum, forL. formosanum andL. longiflorum (all in sect.Leucolirion) and to a lesser extent forL. hansonii, L. martagon, andL. tsingtauense (sect.Martagon). The pattern forL. henryi (previously classed in sect.Sinomartagon) matches those ofL. regale andL. sulphureum quite well and its transfer to sect.Leucolirion is proposed. This is consistent with results from interspecies hybrids betweenL. henryi andL. regale (and related species) which are reportedly fertile. No other clear similarities in C-band patterns were seen across species. It seems that C-band patterns change rapidly inLilium and hence their usefulness in classification will be restricted to identifying closely related species.Dedicated to Prof.D. G. Catcheside on the 80th anniversary of his birth.     

Aegilops cylindrica var.kastorianum (Poaceae): A new variety from Greece

A native population ofAegilops cylindrica was encountered for the first time in Greece in 1980 (near Kastoria, NW. Greece), completely isolated and at a great distance from its main distribution area. There are morphological and chromosomal, but no protein and esterase pattern differences from otherAe. cylindrica populations. This justifies the recognition of a new variety: var.kastorianum. Our comparative and karyotypic observations support the view thatAe. caudata var.polyathera and not var.caudata (typica) is the possible donor of genome C of the new variety.     

Karyotype analyses in three Patagonian and S. Andean endemic genera ofNicotianeae (Solanaceae)

The somatic chromosomes and karyotypes of threeNicotianeae have been studied for the first time. All of them have 2n = 2x = 22 and symmetrical karyotypes.Benthamiella pycnophylloides has 9 m pairs + 1 sm pair + 1 st pair; pairs 2, 4, 5, and 11 bear microsatellites.Combera paradoxa andPantacantha ameghinoi have 9 m pairs + 2 sm pairs; pair 11 ofC. paradoxa is satellited, while pair 9 ofP. ameghinoi bears microsatellites and shows a pericentric inversion in heterozygous state in 20% of the seedlings. Results are compared with previous chromosome reports for the tribe. The cytological data support their present position in the family system. Besides,Benthamiella, Combera andPantacantha appear to be primitive genera ofNicotianeae, a comparatively advanced tribe within the family.Chromosome studies onNicotianeae (Solanaceae) 1.     

Habit differentiation and chromosome evolution inPleione (Orchidaceae)

Karyotypic and heterochromatin studies suggest a basic division of the orchid genusPleione into two groups, one represented by the clearly epiphytic species and the other including both species with terrestrial trends as well as those that are truly terrestrial. The epiphytic group possesses only (sub) metacentric chromosomes and is characterised by a considerable amount of terminal heterochromatin while the terrestrial group has some subtelocentric chromosomes and only small amounts of centromeric heterochromatin. It is concluded that a major phyletic split in the mode of chromosome change occurred during the transition from the epiphytic to the terrestrial habitat.