中国淡水三角涡虫(Dugesia sp)的染色体研究(Ⅰ)

利用空气干燥法对不同产地淡水三角涡虫的染色体进行了研究。核型分析表明：河南淇县鱼泉三角涡虫(Dugesia sp)和浙江杭州龙井三角涡虫(Dugesia sp)体细胞中有16条染色体,为二倍体,核型公式为2n=2x=16=16m,均为具中部着丝粒染色体;河南济源不老泉三角涡虫(Dugesia sp)有24条染色体,为三倍体,核型公式为2n=3x=24=24m,亦全部由中部着丝粒染色体组成。上述3个产地淡水三角涡虫染色体的形态较为接近。北京樱桃沟三角涡虫(Dugesia sp)的体细胞染色体数目为24,为三倍体,核型公式为2n=3x=24=22m 2sm,由中部和亚中部着丝粒染色体组成,其中第2、4号各有一条染色体属于亚中部着丝粒染色体。研究结果表明：4个产地三角涡虫的体细胞染色体数目存在较大差异,包括二倍体(2n=2x=16)和三倍体(2n=3x=24),染色体基数属于x=8类型。     

我国某些蔷薇属花卉的核型研究

本文报道了我国产的5种和14个品种的蔷薇属花卉的染色体数目和核型,结果如下:小花型为二倍体,2n=2x=14,少数为混倍体;中花型为三倍体,2n=3x=21;大花型为四倍体,2n=4x=28。大部分种的核型均由其中部和近中部着丝点染色体组成,少数种具近端着丝点染色体。它们可以区分为3种核型类型,即1A、2A和1B。     

六倍体多星韭的发现及多星韭种内倍性组成及演化的分析

采用染色体常规制片技术,对云南西北部和中部地区11个多星韭居群进行了细胞学分析。结果显示:(1)云南西北部多星韭二倍体、四倍体混合分布的太子阁和华首门四倍体居群中发现了三倍体(2n=3x=21),核型公式分别为:2n=3x=21=[6m(2sat)+8sm]+(3m+4sm)和2n=3x=21=[4m(2sat)+10sm]+(2m+4sm+lst)。三倍体含2条随体染色体,它的21条染色体含2个同源染色体组和一个与它们同源性稍差的染色体组。(2)在云南中部的多星韭四倍体居群中首次发现了六倍体,核型公式为2n=6x=42=15m(3sat)+27sm,核型类型2A。(3)结合核型特征及地理分布对多星韭三倍体和六倍体的成因进行分析,提示多星韭三倍体来源于二倍体与四倍体的杂交,六倍体是通过四倍体产生的未减数配子(n=4x=28)与正常减数配子(n=2x=14)的结合形成的。本研究结果支持多星韭的分化中心是云南西北部高海拔地区的观点,并结合前人的研究和本工作的结果,对多星韭种内的倍性组成和演化进行了分析和讨论。     

中国淡水三角涡虫（Dugesia sp．）的染色体研究Ⅲ

通过空气干燥法对中国4产地淡水三角涡虫染色体和核型进行研究.结果表明:河南省平顶山市石龙和浙江省杭州市龙泉两产地三角涡虫体细胞的染色体数目以二倍体为主(2n=2x=16),极少数为三倍体(2n=3x=24);山西省麻客沟和三叉沟两产地三角涡虫体细胞的染色体数目以三倍体为主(2n=3x=24),少数为二倍体(2n=2x=16)和三倍性非整倍体(2n=3x 1=25=24 1SB).     

田埂报春多倍体诱导及其形态学研究

在离体培养条件下,比较不同浓度、不同处理时间的秋水仙素对田埂报春进行染色体加倍的诱导效果。结果表明:0.08%秋水仙素处理48h的诱变效果最佳,诱变率高达56%。经秋水仙素诱导后形成的多倍体植株与原二倍体植株比较,在形态上,四倍体植株表现出多倍体特征,叶片变厚,叶形指数减小,保卫细胞增大,单位面积气孔数减少,叶绿体数明显增多。对变异植株进行细胞学研究发现,体细胞中期染色体数目为2n=4x=36,而原二倍体的染色体数目为2n=2x=18,基数x=9,因此,变异植株(2n=4x=36)为四倍体。前者的核型公式为2n=4x=8L+12M2+4M1+12S,核型属于1A;后者的核型公式为2n=2x=4L+6M2+2M1+6S,核型也属于1A。检测发现少数个体有非整倍体变异。     

中国淡水三角涡虫染色体变化与生殖的关系

利用空气干燥法对淡水三角涡虫的染色体进行研究。结果表明：三角涡虫的染色体数目为n=8,2n=16,2n=24,为二倍体2n=2x=16、三倍体2n=3x=24和混合倍体2n=2x=16,2n=3x=24,有时也可见到非整倍体。以有性生殖为主的类群．有性生殖期间有性个体大量存在,生殖器官比较发达．染色体为二倍体;以无性生殖为主的类群,很少出现有性个体,染色体为三倍体;既有有性生殖又有无性生殖的类群,有性生殖期间,生殖器官发育稍差,染色体主要为混合倍体．有时出现二倍体或三倍体。本文对影响三角涡虫性成熟的因素也进行了讨论。     

[AAGG]异源四倍体新棉种的核型及同功酶分析

本文对山西农业大学棉花育种组创育的[AAGG]异源四倍体新棉种及其二倍体亲本亚洲棉(G．arboreum)、比克氏棉(G．bickii)进行了核型分析,并对[AG]异源二倍体和[AAGG]异源四倍体的过氧化物同功酶进行了分析。研究结果：异源四倍体[AAGG]的体细胞染色体数目为2n=4x=52,表现为双亲染色体数目之和,其核型公式为2n=4x=52=50m(6SAT) 2sm,按stebbins的核型分析原则,异源四倍体[AAGG]属1A型。过氧化物酶同功酶分析表明：[AG]棉种酶谱表现为双亲不完全互补型。并具有新式酶带。因此过氧化物酶同功酶可以作为鉴别远缘杂种的生物技术之一。     

枸杞胚乳植株的诱导及染色体倍性观察

枸杞[Lycium chinense Mill.var.potaninii(Pojark)A.M.Lu]的未成熟胚乳接种在MS基本培养基上,并添加1毫克/升2,4-D和0.1毫克/升KT,诱导产生愈伤组织,其频率为23.8％。处于色变期的果实为胚乳培养的最适时期。胚在胚乳培养中不是必不可少的,但当有胚存在时可以提高胚乳愈伤组织的诱导频率。胚乳愈伤组织的继代培养对器官分化和植株再生没有明显影响。胚乳植株根尖细胞染色体数目不很一致,甚至有的植株同一根尖的不同细胞染色体数目也有不同。其中有三倍体(2n=3x=36),也有二倍体(2n=2x=24)和非整倍体的细胞,染色体数为9、18等,但从观察的15株胚乳苗来看,三倍体有11株,占73.3％,非三倍体的只有4株,占26.7％。     

月季种质资源的倍性变异及核型多样性研究(英文)

采用常规压片法对包括5个蔷薇野生种、8个古老月季及9个现代月季品种共22份月季种质资源进行核型分析。供试材料共有3种不同倍性:5个野生种中粉团蔷薇为三倍体(2n=3x=21),其他4个材料为二倍体(2n=2x=14);9个现代月季品种均为四倍体(2n=4x=28);而古老月季品种中包含二、三、四倍体3种倍性。22份材料中共发现4种不同类型的核型,在野生种中为1A、2A;古老月季中为1A、2A、1B;现代月季中为1A、1B、2B。另外,供试材料在核不对称系数、着丝粒指数、随体数目及位置、染色体相对长度组成等方面差异较大,说明在月季种质资源中存在着丰富的核型多样性。     

毛花猕猴桃原生质体再生植株根尖染色体数目变异与细胞多核现象

对18株毛花猕猴桃(Actinidia eriantha Benth.)原生质体再生植株的体细胞染色体数做了观察,其中12株为整倍体:二倍体(2n=58)和四倍体(2n=116)各6株;另外6株为混倍体,其染色体数目变化在59～203之间。还发现原生质体再生植株有丝分裂间期细胞存在多核现象,有多核细胞的共10株,细胞核数目以双核和三核较常见,最多的有7个核。对照植株为2n=2x=58,未发现多核细胞。     

Polyploidy and aneuploidy inOphrys,Orchis, andAnacamptis (Orchidaceae)

Studies on chromosome numbers and karyotypes in Orchid taxa from Apulia (Italy) revealed triploid complements inOphrys tenthredinifera andOrchis italica. InO. tenthredinifera there is no significant difference between the diploid and the triploid karyotypes. The tetraploid cytotype ofAnacamptis pyramidalis forms 36 bivalents during metaphase I in embryo sac mother cells. Aneuploidy was noticed inOphrys bertolonii ×O. tarentina with chromosome numbers n = 19 and 2n = 38. There were diploid (2n = 2x = 36), tetraploid (2n = 4x = 72), hexaploid (2n = 6x = 108) and octoploid (2n = 8x = 144) cells in the ovary wall of the diploid hybridOphrys apulica ×O. bombyliflora. Evolutionary trends inOphrys andOrchis chromosomes are discussed.     

中国姜花属十九个分类群的细胞学研究

采用压片法对中国姜花属十八个分类群进行了体细胞染色体计数,对白姜花减数分裂终变期I的染色体数目和形态进行了观察。结果显示:包括白姜花在内的十九个分类群中有六个二倍体,一个三倍体,十二个四倍体,其中十二个分类群的体染色体数目为首次报道,显示中国姜花属植物具有较高比例的多倍体类型;姜花属的染色体基数为n=17,染色体组可能是多倍体起源的。     

Cytotaxonomic study of genusHymenasplenium (Aspleniaceae) in Xishuangbanna, Southwestern China

The gametic chromosome numbers of sevenHymenasplenium (Aspleniaceae) species from Xishuangbanna, Yunnan Prov., China, were investigated. All the examined individuals ofH. obscurum, H. cheilosorum andH. latipinnum were sexual diploids with n=39 chromosomes. Intraspecific cytological variation was found inH. excisum, which has a sexual diploid (n=39) and a tetraploid (n=78). Only a triploid apogamous cytotype (n=ca.117) was found inH. laterepens. Hymenasplenium apogamum showed the most complicated intraspecific variation and included a sexual diploid (n=39), a sexual tetraploid (n=78) and an apogamous triploid (n=ca.117). This work reports for the first time the sexual diploids ofH. cheilosorum andH. apogamum, which are only apogamous elsewhere in east Asia, Himalayas and Indochina. These results may indicate that this area is one of the diversity centers ofHymenasplenium. Most of the above species have chromosome numbers based on x=39. In contrast,H. costarisorum contains a sexual diploid (n=36) and a sexual tetraploid (n=72), indicating that its basic number is x=36.     

Segregation for sexual seed production in Paspalum as directed by male gametes of apomictic triploid plants

BACKGROUND AND AIMS: Gametophytic apomixis is regularly associated with polyploidy. It has been hypothesized that apomixis is not present in diploid plants because of a pleiotropic lethal effect associated with monoploid gametes. Rare apomictic triploid plants for Paspalum notatum and P. simplex, which usually have sexual diploid and apomictic tetraploid races, were acquired. These triploids normally produce male gametes through meiosis with a range of chromosome numbers from monoploid (n = 10) to diploid (n = 20). The patterns of apomixis transmission in Paspalum were investigated in relation to the ploidy levels of gametes. METHODS: Intraspecific crosses were made between sexual diploid, triploid and tetraploid plants as female parents and apomictic triploid plants as male parents. Apomictic progeny were identified by using molecular markers completely linked to apomixis and the analysis of mature embryo sacs. The chromosome number of the male gamete was inferred from chromosome counts of each progeny. KEY RESULTS: The chromosome numbers of the progeny indicated that the chromosome input of male gametes depended on the chromosome number of the female gamete. The apomictic trait was not transmitted through monoploid gametes, at least when the progeny was diploid. Diploid or near-diploid gametes transmitted apomixis at very low rates. CONCLUSIONS: Since male monoploid gametes usually failed to form polyploid progenies, for example triploids after 4x x 3x crosses, it was not possible to determine whether apomixis could segregate in polyploid progenies by means of monoploid gametes.     

Identification of mitotic chromosomes of tuberous and non-tuberous solanum species (Solanum tuberosum and Solanum brevidens) by GISH in their interspecific hybrids.

GISH (genomic in situ hybridization) was applied for the analysis of mitotic chromosome constitutions of somatic hybrids and their derivatives between dihaploid clones of cultivated potato (Solanum tuberosum L.) (2n = 2x = 24, AA genome) and the diploid, non-tuberous, wild species Solanum brevidens Phil. (2n = 2x = 24, EE genome). Of the primary somatic hybrids, both tetraploid (2n = 4x) and hexaploid (2n = 6x) plants were found with the genomic constitutions of AAEE and AAEEEE, respectively. Androgenic haploids (somatohaploids) derived from the tetraploid somatic hybrids had the genomic constitutions of AE (2n = 2x = 24) and haploids originating from the hexaploid hybrids were triploid AEE (2n = 3x = 33 and 2n = 3x = 36). As a result of subsequent somatic hybridization from a fusion between dihaploid S. tuberosum (2n = 2x = 24, genome AA) and a triploid somatohaploid (2n = 3x = 33, genome AEE), second-generation somatic hybrids were obtained. These somatic hybrids were pentaploids (2n = 5x, genome AAAEE), but had variable chromosome numbers. GISH analysis revealed that both primary and second-generation somatic hybrids had lost more chromosomes of S. brevidens than of S. tuberosum.     

Chromosomal variation in immature embryo derived calluses of barley (Hordeum vulgare L.)

Summary Chromosome counts of ten morphogenic and seven non-morphogenic immature embryo derived calluses of barley,Hordeum vulgare L. cv. Himalaya, were determined. Morphogenic calluses carried the normal chromosome complement (2n=2x=14) in a majority of the cells. A low frequency of haploid (2n=x=7), triploid (2n=3x=21), tetraploid (2n=4x=28) and octoploid (2n=8x=56) cells were also observed. In contrast, non-regenerability of a callus was attributed to the cells having numerical and structural chromosomal changes. In these calluses, aneuploid cells around diploid, triploid, and tetraploid chromosome numbers predominated. It has been demonstrated that chromosomal changes were induced during the culture and that they did not pre-exist in the cultured barley embryos. Based on this study, it is suggested that chromosome analysis of a non-regenerable callus should be conducted before altering the media composition.     

Chromosome doubling and mode of reproduction of induced tetraploids of eastern gamagrass (Tripsacum dactyloides L.)

Eastern gamagrass, (Tripsacum dactyloides L.) is a perennial, warm-season grass that is being developed as a forage plant. Shoots were derived from callus initiated from immature embryos and immature inflorescences of diploid (2n=2x=36) gynomonoecious eastern gamagrass. These shoots were induced to microtiller in the presence of 3 mg/l benzyladenine. Amiprophosmethyl (10, 15, or 20 μm) was applied to 27 microtillers for 3–5 days to induce chromosome doubling. All 14 surviving plants were tetraploid, (2n=4x=72), as determined by flow cytometry or chromosome counts. These plants were morphologically normal and produced seed. Test crosses were made with a known diploid. Flow cytometry and chromosome counts showed that the progeny were triploid, proving that the induced tetraploids reproduce sexually. Received: 12 February 1997 / Revision received: 18 February 1998 / Accepted: 13 March 1998     

Ploidy-dependent genomic stability in the tissue cultures of ornamental Phlox drummondii Hook

Comparisons of the chromosome numbers, 2C nuclear DNA amounts and karyomorphology were made in explant cultures of diploid (2n = 2x = 14) and autotetraploid (2n = 4x = 28) Phlox drummondii. In 6–36 week old calli derived from diploid internodal segment explants, and in cells of root tips regenerated from such callus, marked differences were observed in chromosome number. The chromosome numbers ranged from 2n = 14 to 2n = 100 and DNA amounts from 8.20 to 63.20 pg in the diploid derived callus, while the extent of variation was much reduced in the regenerated roots. In contrast, the autotetraploid cultures were characterised by the maintenance of the same chromosome number and DNA amounts as the mother plant. Modified chromosome structures were not apparent in any of the cultures. The possible reasons for the chromosomal instability at the diploid level and stability at the tetraploid level are discussed.     

A biosystematic study on polyploid populations of the genusSpiraea (Rosaceae) in Korea

A total of 61 chromosome counts from 11 taxa of Korean Spiraea was made. Our counts are the first report for eight taxa;S. blumei (2n=18, 36),S. chartacea (2n=36),S. chinensis (2n=36),S. fritschiana (2n=27, 36),S. microgyna (2n=18),S. prunifolia var.simpliciflora (2n=18),S. pseudocrenata (2n=36), andS. trichocarpa (2n=18). A new chromosome number of 2n=36 (tetraploid) is reported forS. pubescence. Populations of three species includingS. blumei, S. pubescence and .V.fritschiana, show different ploidy levels; diploid and tetraploid populations are found in the former two species and triploid and tetraploid ones, in latter species. Multiplication of chromosome numbers contributes to increase in size of pollen and stomata in the three species. Populations with different ploidy levels inS. blumei occupy different regions; diploid populations in inland Korea and tetraploid ones in Ullung Island. Island tetraploid population of 5.blumei might be originated from intra-island polyploidization through the introduction of diploid from inland Korea, considering the worldwide distribution of this species. Pollen fertilities of island populations of ,S′.blumei are relatively low, and sometimes no pollen grain is produced in anther sacs; it suggests that tetraploid population of the island is gynodioecious which may serve reduction of inbreeding depression.