Chromosome characterization and variability in some Iridaceae from Northeastern Brazil

The chromosomes of 15 species of Iridaceae of the genera Alophia, Cipura, Eleutherine, Neomarica and Trimezia (subfamily Iridoideae) were examined after conventional Giemsa staining. The karyotypes of Alophia drummondii (2n = 14+1B, 28, 42 and 56), Cipura paludosa (2n = 14), C. xanthomelas (2n = 28) and Eleutherine bulbosa (2n = 12) were asymmetric; Neomarica candida, N. caerulea, N. humilis, N. glauca, N. gracilis, N. northiana and Neomarica sp. (2n = 18); N. cf. paradoxa (2n = 28), Trimezia fosteriana (2n = 52), T. martinicensis (2n = 54) and T. connata (2n = 82) were all generally symmetric. New diploid numbers of 2n = 56 for Alophia drummondii, 2n = 18 for N. candida, N. humilis, N. glauca, and N. gracilis, 2n = 28 for N. cf. paradoxa, and 2n = 82 for T. connata are reported. The karyotypic evolution of the studied species is discussed.     

Cytogeography of the South American Turnera sidoides L. complex (Turneraceae, Leiocarpae)

New chromosome number determinations are presented for 48 populations of five subspecies of Turnera sidoides. Chromosome counts in sspp. carnea, holosericea, integrifolia and sidoides confirm previous data while, in ssp. pinnatifida , the numbers 2n=2x = 14 and 2n = 6x = 42 are reported for the first time. The results show that polyploidy is a very frequent phenomenon. Populations are primarily tetraploids (2n = 4x = 28), while diploids (2n = 2x = 14), hexaploids (2n = 6x =42) and octoploids (2rc = 8x = 56) are less frequent. Diploid, tetraploid and hexaploid cytotypes occur in sspp. carnea and pinnatifida , whereas tetraploids and hexaploids are known in ssp. holosericea. Turnera sidoides ssp. integrifolia shows a polyploid series with ploidy levels from 2x to 8x. The ssp. sidoides appears to be uniformly tetraploid, with the exception of an isolated pentaploid (2rc = 5x = 35). On the basis of these counts and previous reports the geographical distribution of the cytotypes has been determined and related to climatic and ecological factors.     

六种犁头尖属植物(天南星科)的核型研究

报道了 6种 8个居群犁头尖属 ( Typhonium Schott)植物的核型 ,其结果如下 :( 1 )独角莲 ( T.gigan-teum)北京居群 2 n=4 x=5 2 =4 4m+ 7sm+ 1 st;( 2 )鞭檐犁头尖 ( T.flagelliforme)金平居群 2 n=3x=2 4 =3m+ 9sm( 4 SAT) + 1 2 st,河内居群 2 n=4 x=32 =7m+ 2 0 st+ 4sm+ 1 t;( 3)单籽犁头尖 ( T. calcicolum)西畴居群2 n=4 x=5 2 =2 1 sm+ 2 3m( 5 SAT) + 8st;( 4 )犁头尖 ( T.blumei)重庆居群 2 n=4 x=5 2 =4 0 m( 1 SAT) + 1 2 sm( 3SAT) ;( 5 )马蹄犁头尖 ( T.trilobatum)西双版纳居群 2 n=2 x=1 8=4 sm( 2 SAT) + 1 2 m+ 2 st,河内居群 2 n=2 x=1 8=2 st+ 9m+ 7sm;( 6 )金慈菇 ( T. roxburgii)个旧居群 2 n=2 x=1 8=8sm+ 1 0 m( 2 SAT)。其中鞭檐犁头尖 2 n=2 4、32 ,金慈菇 2 n=1 8均为首次报道 ,同时分析讨论了本属植物染色体基数和倍性的多样性及其可能的原始基数     

A karyological study of Asphodelus L. (Asphodelaceae) from the Western Mediterranean

The following aspects of Asphodelus karyology are analysed: base number, polyploidy, chromosome size, chromosome morphology, satellited chromosomes, structural heteromorphism, karyotype asymmetry and karyotype evolution. The base number 0 ×= 14 is common to all species except for A. refractus , which has the derived ×= 13. Three ploidy levels occur, often in the same species; diploid, tetraploid and hexaploid, with 2n = 28, 56 and 84. Chromosomes are generally small to medium-small, with the occasional presence of medium-large chromosomes. The most frequent chromosome types are metacentric of type m and submetacentric. Metacentric chromosomes of type M occur only in sections. Verineopsis, Verinea and Plagiasphodelus ; subtelocentric chromosomes occur only in sections Asphodelus and Plagiasphodelus. There is a wide variability in relation to the number of satellited chromosomes, relative to ploidy level. There are usually two to four in diploids, four to eight in tetraploids and usually six, exceptionally up to 12, in the hexaploid. Satellites are present on the shortest arm, exceptionally on the longest arm. There is a high degree of structural heteromorphism in practically all the species which affects satellited and non satellited chromosomes. Karyotype asymmetry is generally of type 2B. Inter-and intra-chromosomal differences are estimated by the A1 and A2 indexes. Both indices vary in the karyotype evolution of the genus, with a decrease of A1 and an increase of A2. The role of polyploidy, hybridization, asymmetry and decrease of chromosome size in the evolution of Asphodelus is discussed.     

Chromosome studies in Orchidaceae from Argentina

The center of diversity of Argentinean orchids is in the northeast region of the country. Chromosome numbers and karyotype features of 43 species belonging to 28 genera are presented here. Five chromosome records are the first ones at the genus level; these taxa are Aspidogyne kuckzinskii (2n = 42), Eurystyles actinosophila (2n = 56), Skeptrostachys paraguayensis (2n = 46), Stigmatosema polyaden (2n = 40) and Zygostates alleniana (2n = 54). In addition, a chromosome number is presented for the first time for 15 species: Corymborkis flava (2n = 56), Cyclopogon callophyllus (2n = 28), C. oliganthus (2n = 64), Cyrtopodium hatschbachii (2n = 46), C. palmifrons (2n = 46), Galeandra beyrichii (2n = 54), Habenaria bractescens (2n = 44), Oncidium edwallii (2n = 42), O. fimbriatum (2n = 56), O. pubes (2n = 84), O. riograndense (2n = 56), Pelexia ekmanii (2n = 46), P. lindmanii (2n = 46) and Warrea warreana (2n = 48). For Oncidium longicornu (2n = 42), O. divaricatum (2n = 56) and Sarcoglottis fasciculata (2n = 46+1B?, 46+3B?), a new cytotype was found. Chromosome data support phylogenetic relationships proposed by previous cytological, morphologic and molecular analyses, and in all the cases cover some gaps in the South American literature on orchid chromosomes.     

昆虫细胞分类学的基本问题及染色体系统发育的重建方法

本文非昆虫细胞遗传学及细胞分类学原理与技术的全面评述;而是从细胞遗传学特征（或称染色体特征）在混虫分类学中的应用入手,重点提出与分析了昆虫细胞分类学中的种类鉴定,研究取材,染色体多态现象,多倍体及核型进化方向等基本问题,并着重总结了目前国际上细胞水平染色体数据的处理方法,即传统法,倒位法,数值法与支序法;最后,作者指出了正确看待细胞分类学重要性的态度。     

天门冬科广义铃兰族的染色体数目与核型进化研究

广义铃兰族包括6属200余种单子叶植物,具有较为稳定的染色体数目以及明显的核型变化,是研究植物染色体进化非常理想的类群.该研究采用常规压片法对铃兰族5个物种植物的染色体形态、数目及其核型进行了观察分析,并全面收集和整理了铃兰族所有已报道的共81种253条的染色体记录,通过综合统计、重建系统发育树,探讨铃兰族属间以及各属...