黄芩的花粉母细胞减数分裂及核型分析

采用压片法,对黄芩花粉母细胞减数分裂及核型进行了研究。结果表明:黄芩的大多数花粉母细胞减数分裂中染色体的行为正常,在终变期同源染色体配对后可形成9个二价体,后期Ⅰ染色体以9∶9的方式向细胞两极分离,其减数分裂为同时型;在少数花粉母细胞减数分裂中观察到落后染色体、染色体桥等异常行为;其花粉粒育性为76.49%。黄芩的染色体数目为2n=2X=18,核型公式为K(2n)=2X=18=16m+2 sm,染色体相对长度组成为2n=1 s+4M1+3M2+1L,其核型为"1A"型。     

番木瓜核型和减数分裂研究

对番木瓜核型和花粉母细胞减数分裂行为的研究表明,番木瓜染色体数目为2n=18,由9对中部着丝粒染色体组成。核型公式为2n=2x=18m。花粉母细胞减数分裂正常,在终变期和中期Ⅰ观察到9个二价体,未观察到染色体结构变异和行为异常。     

亚铁杂交百合红芯Fangio的染色体与其加倍方法研究

对亚铁杂交百合红芯Fangio,进行了染色体数目、花粉母细胞减数分裂行为和染色体核型研究,结果表明：红芯为三倍体,染色体数为2n=3x=36;花粉母细胞减数分裂异常;染色体组成为：R(2n)=3x= R(2n)=3x=12m(SAT)+3sm+3sm(SAT)+12st+3st(SAT)+3t,在第2、4、8、9、10、12染色体上有随体,其核型分类属于3B 型。用不同浓度秋水仙素对其试管苗和鳞片处理不同时间,均对诱导红芯百合染色体加倍有效,最高变异率达20%以上,部分变异苗为六倍体。     

紫竹梅的减数分裂与核型分析

以紫竹梅根尖和花药为材料,分析鸭跖草科紫竹梅的染色体组型,并观察花粉母细胞减数分裂过程中的染色体行为。紫竹梅体细胞染色体数目为24,由12对中着丝粒染色体组成,核型公式为2n=2x=24m。花粉母细胞减数分裂正常,在第一次分裂中期观察到12个二价体,与观察到的体细胞染色体数目互相印证。     

白花丹参的核型分析及小孢子发生过程观察

对白花丹参(Salvia miltiorrhiza f.alba)进行了核型分析及小孢子发生过程观察.结果表明,白花丹参染色体数目为2n=16,核型公式为2n=16=8m+8sm,其中2条染色体具有随体,没有观察到多倍体细胞和B染色体;16条染色体在减数分裂中期I正常配对形成8个二价体,减数分裂的胞质分裂属于同时型;在白花丹参的减数分裂前期I观察到频率较高的细胞融合现象.白花丹参的核型为2B型,其花粉母细胞中的细胞融合现象为首次报道.     

二倍体矮牵牛花粉母细胞异常减数分裂的观察与核型分析

以夏季高温时期二倍体矮牵牛花蕾为材料,采用常规制片法,对花粉母细胞异常减数分裂进行观察并选取终变期进行染色体核型分析。结果发现:异常减数分裂主要表现为具有多核仁、二价体提前分离成单价体、赤道板外的染色体,姊妹染色单体提前分离、不均等分离,落后和丢失染色体,具有微核的三分体和四分体,中期Ⅱ纺锤体定位发生异常出现融合纺锤体和八字形纺锤体可导致2n花粉产生;矮牵牛终变期核型公式为K(2n)=2x=14=10m+4sm(2SAT),其中第1、4、5、6、7号为中部着丝粒染色体,第2号(具有随体)、3号为亚中部着丝粒染色体,染色体相对长度组成为2n=14=4M_1+10M_2,核型分类为2A型。研究表明,矮牵牛异常减数分裂可导致2n花粉和不育花粉的产生,利用终变期进行核型分析具有材料丰富、二价体形态清晰不需人为配对分析等优点,为矮牵牛细胞学研究提供了新方法。     

披碱草与新麦草属间杂种的细胞遗传学研究

将澳大利亚披碱草(Elymus scabervar.scaber,2n=6x=42,StYW)和华山新麦草(Psathyrostachys huas-hanica,2n=2x=14,Ns)进行属间杂交,成功获得杂种F1。分析亲本及其杂种F1的形态特征、繁育特性及花粉母细胞减数分裂染色体配对行为发现:杂种F1形态特征介于父母本之间,分蘖数等农艺性状超过双亲;花粉完全不育,结实率为0。亲本减数分裂染色体配对正常,但杂种F1花粉母细胞在减数分裂中期I染色体几乎没有配对,其构型为:27.31Ⅰ 0.01Ⅱ(环) 0.32Ⅱ(棒) 0.01Ⅲ,C值仅为0.01。以上结果表明:澳大利亚披碱草的StYW染色体组与华山新麦草的Ns染色体组间无同源性,它们之间的亲缘关系甚远。     

斑叶蒲公英的核型分析和花粉母细胞的减数分裂观察

采用根尖压片法确定斑叶蒲公英的染色体数目,通过分析斑叶蒲公英核型及花粉母细胞减数分裂过程,以确定其倍性水平。结果表明:(1)斑叶蒲公英根尖细胞染色体数目为32条,核型公式为2n=3x+x′=32=(18m+6sm)+(3m+4sm+1T),属于2A型。(2)斑叶蒲公英花粉母细胞减数分裂为同时型胞质分裂,四分体的排列方式以正四面体型居多,十字交叉型偏少,偶见左右对称型。(3)前期Ι染色体的构型复杂,中期Ι和中期Ⅱ有赤道板外染色体;后期Ι和后期Ⅱ出现落后染色体、染色体桥及断片;后期Ⅱ和末期Ⅱ还出现染色体分离不同步及不均等分裂的现象;四分体时期出现二分体、三分体、含微核的异常四分体及多分体等异常现象。(4)对其花粉进行离体萌发试验,花粉萌发率只有26.3%,说明斑叶蒲公英是异源四倍体,32条染色体不均等的减数分裂异常,造成花粉活性较低。     

木立芦荟小孢子母细胞减数分裂与花粉育性关系的初步研究

文章从减数分裂过程、小孢子发育两方面,探讨了木立芦荟（Aloe arboresens Mill.）花粉败育的原因。木立芦荟花粉母细胞染色体数目为2n=14,由四对长染色体和三对短染色体组成,属二型性核型。其减数分裂异常,发现存在单价体和多价体、染色体桥、落后染色体、不均等分离、微核等。同时观察到木立芦荟染色体具有极度的粘质性,使减数分裂各阶段的染色体不易散开。统计各种异常现象出现的频率并分析了这些异常现象形成的可能机制及对正常小孢子形成的影响,推测染色体间的丝状粘连可能是木立芦荟小孢子母细胞减数分裂异常并导致败育花粉产生的主要因素。成熟花粉粒中90%以上为败育花粉,属碘败型。     

野蔷薇一变种红刺玫的细胞学研究

以野蔷薇的-变种红刺攻(Rosa multiflora Thunb.vat.cathayensis Rehd.)为材料,对其染色体数和花粉母细胞的减数分裂进程进行了研究.结果表明:红刺玫染色体数目为2n=3x=21,为三倍体;减数分裂始于4月上旬,此时花苞开始膨大、但未开裂,花瓣由绿变成黄色;在同一花药中,花粉母细胞的减数分裂并不同步,可以观察到前期到末期Ⅱ之间各个时期的分裂相;在其减数分裂过程中存在诸如单价体、染色体桥、落后染色体等一系列异常现象.实验还从细胞遗传学上分析了红刺玫育性与花粉母细胞减数分裂异常的关系,部分可育花粉的存在为红刺玫育种实践提供了有用的材料.     

濒危植物巴东木莲花粉母细胞减数分裂观察

对巴东木莲Manglietia patungensis及其近缘种乳源木莲M. yuyuanensis的花粉母细胞减数分裂过程的基本特征进行了比较研究。乳源木莲与巴东木莲的染色体数目和核型相同,但不经任何人为因素诱导,它们之间在减数分裂过程中的染色体行为上有明显差异。(1)巴东木莲减数分裂中期I构型为0.30IV+18.33II+0.15I,与乳源木莲构型19II不同,巴东木莲可能存在同臂内倒位杂合子,染色体结构存在一定的杂合性。(2)后期I和后期II染色体行为异常现象发生频率明显不同。以后期II为例,乳源木莲减数分裂相中有迟滞染色体的细胞占8.8%,迟滞染色体不超过2个;巴东木莲有迟滞染色体等异常现象的细胞占29.2%,迟滞染色体最高达11个,还出现染色体碎裂成断片现象。巴东木莲减数分裂过程中染色体组表现出染色体结构杂合变异和迟滞染色体与染色体的断裂频率很高的异常现象在一定程度上可能影响了雄配子体的发育。     

Cytomixis and meiotic abnormalities during microsporogenesis are responsible for male sterility and chromosome variations in Houttuynia cordata

Houttuynia cordata (Saururaceae) is a leaf vegetable and a medicinal herb througout much of Asia. Cytomixis and meiotic abnormalities during microsporogenesis were found in two populations of H. cordata with different ploidy levels (2n = 38, 96). Cytomixis occurred in pollen mother cells during meiosis at high frequencies and with variable degrees of chromatin/chromosome transfer. Meiotic abnormalities, such as chromosome laggards, asymmetric segregation and polyads, also prevailed in pollen mother cells at metaphase of the first division and later stages. They were caused by cytomixis and resulted in very low pollen viability and male sterility. Pollen mother cells from the population with 2n = 38 showed only simultaneous cytokinesis, but most pollen mother cells from the population with 2n = 96 showed successive cytokinesis; a minority underwent simultaneous cytokinesis. Cytomixis and irregular meiotic divisions appear to be the origin of the intraspecific polyploidy in this species, which has large variations in chromosome numbers.     

Karyotype Analysis of Eight Species of Polygonatum Mill.

Meiosis and mitosis of eight species of Polygonatum from Sichuan, China, were investigated. Ten bivalents (n=10) at meiosis of pollen mother cells were observed ih P. odoratum (Mill.) Druce. Meiotic observation on pollen mother cells in P. punctatum Royle ex Kunth shows 16 bivalents (n=16) at diakinesis, P. kingianum Coll. et Hemsl. 13 bivalents (n=13) at diakinesis. P. zanlanscianense Pamp. 15 bivalents (n=15) in MI, P. cirrhifolium (Wall.) Royle 28 bivalents at diakinesis. Somatic chromosomes were observed in root tip cells. The karyotype formulae are as follows: P. odoratum (Mill.) Druce K(2n)=20=4st+6sm+10m; P. cyrtonema Hua K(2n)=20=6sm+14m; P. punctatum Royle ex Kunth K(2n)=32=2t+8st+ 2sm+20m; P. kingianum Coll. et Hemsl. K(2n)=26=8st(2SAT)+14sm+4m; P. alternicirrhosum Hand.-Mzt. K(2n)=32=6st+8sm+18m(2SAT); P. zanlanscianense Pamp. K(2n)=30= 2t+6st+6sm+16m(2SAT); P. sibiricum Delar. ex Redouté K(2n)=24=2t+14st(2SAT)+6sm +2m; P. cirrhifolium (Wall.) Royle K(2n)=56=18st+10sm+28m. The karyotypes of P. punctatum, P. kingianum, P. alternicirrhosum and P. cirrhifolium are reported for the first time. Both the chromosome number and structure in our materials are certainly different from thoses in previous reports. Of numerical variation polyploidy and aneuploidy have been recorded, and aneuploidy is frequent. According to degree of asymmetry of the karyotype, the 8 species are divided into three types: 2B, 3B, 2C. The increasing asymmetry is correlated with the increasing of the chromosome number. There are no obvious differences in chromosome number and karyotype between Alternifolia Baker and Verticillate Baker. They are not two natural groups. This opinion is different from that of Therman and Suomalainen.     

核桃属部分种的小孢子发生及核型研究

本试验采用常规压片法,观察了核桃属(Juglans L.)四个种花粉母细胞(PMC)的减数分裂过程和花粉形态,检测了两个种的花粉生活力,分析研究了七个种的核型。结果表明,普通核桃(J.regia)核桃楸(J.mandskurica Maxim.)和黑核桃(J.nigra L.)的PMC减数分裂基本正常,但河北核桃PMC的减数分裂过程都极不正常,供试的七个种,除普通核桃为2C核型外,其余均为2B核型,仅黑核桃一种带有随体染色体。根据核型特点把七个种分成三组,并探讨了组间与组内种间的亲缘演化关系。作者认为,河北核桃应为一种独立的种,核桃科在系统发育上可能来源于染色体基数为8的两群)不同植物。     

鱼腥草花粉母细胞减数分裂特征及其育性研究

为深入了解鱼腥草花粉母细胞的减数分裂特征与花粉育性的关系,该研究采用卡宝品红染色法对2个鱼腥草居群花粉母细胞的减数分裂过程进行观察,并采用氯化三苯基四氮唑(TTC)染色法、I2-KI染色法、B-K培养基培养法及荧光显微镜观察法来检测鱼腥草花粉的活力及萌发率。结果发现:(1)鱼腥草减数分裂的进程与花序大小、花药颜色、花药长度均有密切的关系。(2)2个居群的鱼腥草中花粉母细胞减数分裂过程正常占88.2%,有11.8%的花粉母细胞减数分裂异常。(3)减数分裂异常表现在减数分裂过程中出现微核、落后染色体、染色体桥、不均等分离、多分体等现象,并发现在二分体阶段及单核花粉发育过程中存在细胞融合。(4)2个居群的鱼腥草花粉活力均不超过1.5%,花粉几乎不萌发。研究认为,鱼腥草花粉育性低的主要原因是单核花粉的发育过程异常,而非鱼腥草花粉母细胞减数分裂异常所致。     

药蒲公英减数分裂异常行为探讨

对药蒲公英减数分裂各期进行了观察,研究得出药蒲公英花蕾直径大小与花粉母细胞减数分裂各期之间的关系(花蕾直径在2-7mm时为减数分裂期)。并发现药蒲公英减数分裂中出现许多异常行为。如后期桥和落后染色体;药蒲公英花粉粒空瘪,这些异常行为的原因是减数分裂过程中有倒位和重复缺失等染色体结构变异出现以至形成双着丝点染色体。减数分裂过程的异常行为也说明药蒲公英是多倍体。     

温度对斯托克通氏烟草雄配子体形成和发育的影响

为探究低温对斯托克通氏烟草(Nicotiana stocktonii)花粉母细胞(PMC)减数分裂及其雄配子体发育过程的影响,采用卡宝品红染色法,研究不同温度条件下该材料雄配子体形成和发育的过程。结果表明:种植于昼温(31±0.5)℃、夜温(11±0.5)℃人工气候箱中的Nicotiana stocktonii花粉母细胞减数分裂过程异常现象较少,出现微核的比率较低,用新鲜成熟的花粉做萌发实验花粉萌发率较高,为(71±3)%; 而种植于昼温(25±0.5)℃、夜温(3±0.5)℃条件下的Nicotiana stocktonii开花后花药大多干瘪,用新鲜成熟花粉做萌发实验花粉萌发率低,为(13.67±3)%,花粉母细胞减数分裂过程出现染色体桥、染色体不同步、染色体断片、落后染色体等现象,存在微核的细胞比率较高。因此,Nicotiana stocktonii花粉母细胞减数分裂与小孢子发育过程易受温度影响,从而影响花粉的可育性。     

Male and female meiosis in diploid and colchitetraploid Phlox drummondii Hook. (Polemoniaceae)

Comparative studies on male and female meiosis in diploid (2n = 2x = 14) and colchitetraploid (2N = 4x = 28) ornamental Phlox drummondii reveal higher chiasma frequency in embryo-sac mother cells as compared with pollen mother cells in the diploid, and significant differences in the pairing properties of chromosomes in the pollen mother cells and embryo-sac mother cells of the colchitetraploid. Male meiosis in the colchicine-induced autotetraploid was abnormal with 51.70% of chromosomes associated in quadrivalents and tridents in 96% of the cells. This was followed by discordant anaphase I disjunction. In the female meiocytes the chromosomes formed 14 bivalents in 86.66% of the cells. Quadrivalents (1–3) appeared only in 13.34% of the cells. It is concluded that meiosis in male and female cells of the colchitetraploid is governed and regulated by different controlling systems of gene(s).     

Chromosomes of Six Fabaceous Species from Baoxing County,Sichuan Province

Meiosis and/or mitosis of six species of Fabaceae (Leguminosae) from Baoxing County, Sichuan, China, were investigated. The voucher specimens are conserved in PE. Eight pairs (n=8) and 10 chiasmata in meiosis of pollen mother cells have been observed in Medicago lupulina L. (Pl. 1, A-C). Meiotic observation on pollen mother cells in Lotus tenuis W. et K. shows 6 bivalents (n=6) in MI and 9 chiasmata in diakinesis (Pl. 1, D-E). In this species 12 somatic chromosomes (2n=12) in anther wall cells have also been observed. The chromosomal formula may be expressed as 2n=12=8m+2sm+2sm^SAT (Pl. 1, F-G). In pollen mother cells of Vicia tetrasperma (L.) Schreb., 7 bivalents in MI and 7 chromosomes in A II have been observed (Pl. 2, A-B). From A II (Pl. 2, B, the inset on the right) the chromosomal formula, n=7= 2m+2sm+lst^SAT+2t, may be constructed. Only three chromosomes in this karyotype may be found to have counterparts in the one reported by Srivastava (1963), which shows striking differences between these two karyotypes. Meiotic MI shows 7 pairs (n=7) in Vicia hirsuta (L.) S. F. Gray. Vicia sativa L. is very variable in its chromosomes. Our observation shows 6 pairs (n=6) in MI and in diakinesis in pollen mother cells. In Vicia villosa Roth, all the previous chromosome reports are 2n=14 or n=7, but the result of our work shows that somatic chromosomes are 2n=12 in anther wall cells (Pl. 3, D, E). The karyotype in our material (Pl. 3, E) is that the longest pair of chromosomes are metacentric, the pairs 2-4 are terminal, 5 are metacentric and last pair are submetacentric, differing vastly from the idiogram (Pl. 3, F) presented by Yamamoto (1973). Therefore both the chromosome number and structure in our material are greatly different from those in all the previous reports. The evolutionary trends of chromosomes in the genus Vicia is discussed in the work. Srivastava (1963) holds that the primitive basic number of chromosome in the genus is 6 and thus both 5 and 7 are derived. The present author would propose another possibility that 7 is the original basic number and the other numbers are derived ones. First, as shown in Table 1, x=7 occurs in 47 per cent of species in the genus, but 6 only in 28 per cent. Secondly, x=7 is predominant in the perennial and primitive section Cracca. Thirdly, in genera related to the genus under consideration, such as Lens, Pisum and Lathyrus, x=7 is also the predominant basic number. Fourthly, according to Raven (1975) 7 is the primitive basic number in the angiosperms and x= 7, 8 and 9 are the predominant in the angiosperms.