同源四倍体水稻恢复系TP-4和D明恢63与保持系D46B的细胞遗传学比较

以高结实率的同源四倍体水稻恢复系TP-4和D明恢63及优良保持系D46B为材料进行细胞遗传学研究。所有四倍体材料的染色体组成均为2n = 48, 这与有丝分裂的结果一致。恢复系TP-4和D明恢63及保持系D46B的中期Ⅰ单价体和三价体的比例都很低, 配对染色体的比率在99%以上, 具有优良的细胞学特征。恢复系TP-4和D明恢63在中期Ⅰ四价体频率分别为2.00/PMC和2.26/PMC, 而保持系D46B在中期Ⅰ四价体频率为6.00/PMC, 极显著地高于恢复系品系因而具有更好的染色体配对性质; 后期Ⅰ保持系D46B的染色体滞后频率为10.62%, 远低于恢复系材料TP-4的19.44%和D明恢63的23.14%, 接近二倍体对照明恢63的7.30%水平; 末期Ⅰ保持系D46B具有比恢复系更低频率的微核数而末期ⅡD46B的正常四分小孢子比率不但高于恢复系品系甚至高于二倍体对照。相关分析表明后期Ⅰ染色体滞后细胞比率同末期Ⅰ异常细胞比率呈极显著的正相关, 推测后期Ⅰ染色体分离和末期Ⅰ微核形成可能是由相同的显性单基因或主效基因控制。     

将大赖草种转移给普通小麦的研究Ⅵ.端体异附加系的选育与鉴定

利用根尖细胞有丝分裂中期染色体计数、花粉母细胞减数分裂中期Ｉ（ＰＭＣＭＩ）染色体构型分析以及Ｃ－分带,从普通小麦中国春与大赖草（ＬｅｙｍｕｓｒａｃｅｍｏｓｕｓＬａｍ．）杂种回交后代中,选育出两个端二体异附加系９５Ｇ０９．９５Ｇ１１和一个添加了一时大赖草第１４号染色体和另一对端体的双重异附加系９５Ｇ３０２（２ｎ＝４４＋２ｔ）,它们的ＰＭＣＭＩ染色体配对构型分别为０．２１个单价体（其中０．１６个端体单价体）、１９．５７个环状二价体＋２．３２个棒状二价体（其中０．９２个由两端体配对构成）,１．５２个单价体（１．４４个端体单价体）＋１８．０７个环状二价体＋３．１７个棒状二价体（０．２８个由两端体配对构成）,１．０３个单价体（０．７２个端体单价体）＋１８．８９个环状二价体＋３．６１个棒状二价体（０．６４个由两端体配对构成）。运用单花滴注技术对这些材料在活体和离体条件下进行赤霉病人工接种鉴定,结果表明：９５Ｇ３０２的抗性与抗赤霉病对照品种苏麦３号相仿;９５Ｇ１１的抗性高于苏麦３号,明显高于亲本品种中国春。还对端体附加系的利用以及有效、快捷地转移赤霉病抗性基因进行了讨论。     

粘型小麦不育系育性恢复性的细胞遗传学研究

利用5个粘性不育系分别与中国春的二体,1B重双端体及1B°1D^Ⅳ缺四体杂交,调查其F1的育性及其F1减数分裂中期Ⅰ的染色体配对情况和后期Ⅰ出现落后染色体的细胞频率。结果表明：（1）5个不育系与中国春二体杂交F1的自交结实率存在明显差异。中国春的1B重双端体使5个不育系的自交结实率大幅度下降,中国春的1B°1DⅣ缺四体使各不育系表现全不育;（2）5个不育系和3个父本杂交F1减数分裂中期Ⅰ出现单价体细胞的频率与其后期Ⅰ出现落后染色体细胞的频率不存在直接相关;（3）5个不育系与中国春二体的杂交F1自交结实率与其减数分裂中期Ⅰ出现单价体细胞的频率呈正相关。相关系数为0.9695**,与后期Ⅰ出现落后染色体细胞的频率不直接相关。     

用中国春双端二体分析西藏小麦的染色体构成

用普通小麦“中国春”双端二体系列(double ditelosomics)作母本分别与西藏小麦杂交,对全套21个F_1的PMC在MI进行端体配对分析。在(“中国春”双端二体7B×西藏小麦)F_1中,含有(t′,t1″)构型的PMC占观察总数的87.3％,7BS常不参与配对,显示出有较大差异。“中国春”3A、7A、2D—7D等8条染色体的两臂可以分别同时与西藏小麦对应染色体配成异型三价体(tt1′′′)的PMC频率达80.0—95.5％,表明西藏小麦与“中国春”之间这8条染色体差异很小。在涉及其余12条染色体的组合中,出现(tt1′′′)、(t′t1″)和(t′,t′)构型的PMC分别占观察细胞总数的42.3—77.6％、21.9—55.5％和0—8.0％,表明它们之间仅某个染色体臂间有轻度变异或分化。从总体来看,西藏小麦与“中国春”之间除7BS有较大差异外在染色体构成上基本相似。     

八倍体小偃麦与天蓝偃麦草杂交F1染色体组构型

首次获得麦草8号、麦草9号、远中2号八倍体小偃麦与天蓝偃麦草的属间杂种,杂交当代结实率为31.49%,39.28%和10.41%。杂种F1表现为两亲的中间型,植株高大、繁茂,穗长20~30 cm,小穗数25~30个,多年生,抗寒,在哈尔滨冬季无覆盖条件下可安全过冬。对F1植株进行减数分裂行为观察,结果发现,染色体配对不正常,单价体频率高,出现多价体。杂种F1减数分裂中期I染色体配对构型分别为:9.5Ⅰ+16.98Ⅱ+0.27Ⅲ、13.6Ⅰ+14.01Ⅱ+0.87Ⅲ、11.2Ⅰ+16.8Ⅱ+0.08Ⅲ。二价体数变动在13~18间、单价体数变动在11~17间、多价体变动在0.08~0.87间,二价体多数是棒状二价体,推测两亲有一对部分同源关系染色体组,其余为非同源染色体组,但有的染色体间有部分同源关系。小麦5B染色体上Ph基因可能受到E组染色体的抑制。     

小麦品种小偃6号染色体结构变异的细胞学研究

本文报道了小麦品种小偃6号的染色体结构变异。小偃6号及其亲缘品种与中国春小麦杂交,杂种F_1染色体配对资料表明:小偃6号及其父本小偃96与中国春在染色体结构上有很大差异。八倍体小偃麦小偃693与小偃6号和小偃96杂种F_1减数分裂中期出现19″+2′′′+5′的染色体构型,说明小偃6号和小偃96至少含有两个长穗偃麦草染色体片段。将小偃6号与中国春双端体系列杂交,杂种F_1中1AL、2AS、5AS、6AS和7BS端着丝点染色体配对频率极显著地低于(中国春×小偃6号)F_1的平均染色体臂配对频率(90.1％),从而将小偃6号中的异源片段局限于这5个染色体臂内;同时发现:1AL、2DS、4DS、6AL及3B(t″s+t′L)端体中的端着丝点染色体参与了杂种F_1中多价体的形成,或与此有关,故认为小偃6号与中国春至少有两个相互易位的差异,涉及到染色体1A、2D、3B、4D和6A。文章还对小偃6号异源易位的起源和鉴定等进行了讨论。     

一个小麦—黑麦染色体代换的细胞学鉴定

对从六倍体小黑麦与普通小麦的杂种后代中获得的矮秆抗病选系84056-1-36-1进行体细胞C-分带鉴定,结果表明,它的21对染色体中,有1对短臂带型与1R相似的黑麦染色体代换了小麦的1D。观察“中国春”双端二体1A、1B与该选系杂种F_1的花粉母细胞染色体配对,发现分别有82.56%和65.71%的细胞出现异型三价体,所有细胞至少有两个形态不同的单价体;而在“中国春”端二体IDL与84056-1-36-1的杂种中,端体不配对的花粉母细胞占100%,经C-分带后,另外1条单价体显示明显的端带。从上述这些结果推断84056-1-36-1为1R(1D)代换系。     

番茄属种间杂种离体培养F1植株的细胞学分析

本文报道了栽培番茄（Lycopersico esculentum)“北京早红”等5个品种分别与野生型秘鲁番茄（L.peruvianum)PI128657中8号株系杂交,离体胚培养,得F1杂种植株,对花粉母细胞在减数分裂中染色体行为和终变期二价体交叉点的频率,以及亲和性程度等进行了.结果表明,6个亲本植株花粉母细胞减数分裂染色体的行为是正常的,中期I为12个二价体。其中环状二价体占多数,棒状二价体数较少,中期I没有单价体,后期I和II均正常,四分体阶段无微出现,但各亲本在终变期和中期I的环状二价体和棒状二价体的数有一定的差异,这可能与不同亲本基因型的亲和性程度和在遗传学上的不协调有关。5个组合的大多数F1杂种花粉母细胞减数分裂中染色体行为基本正常,12个二价体占多数,但染色体配对不稳定,有较多的单价体,染色单体桥。四分体阶段有微核,此外,在5个组合的F1杂种植株中,均出现双二倍体花粉母细胞,这些双二倍体花粉母细胞的染色体,在减数分裂中,也均,出现落后染色体和染色单体桥,以及较多的多价体,四分体阶段有微和不同类型的四分孢子群。     

小麦ph1b突变体与小黑麦杂交的细胞遗传学研究

本文利用普通小麦品系"中国春"(对照)、中国春ph1b突变体分别与八倍体小黑麦、六倍体小黑麦杂交,杂种F1的减数分裂前期Ⅰ染色体行为表现异常,中期Ⅰ出现较多的单价体、棒状二价体和多价体,在后期和末期出现落后染色体、染色体片断和微核。原因是ph1b基因的存在造成染色体联会机制紊乱,致使一些部分同源染色体配对并发生互换,有可能在以后的世代产生染色体易位与基因重组。     

辣椒属种间杂种F1植析的细胞遗传学研究

本文分析了早椒和Ｃ;ｈｉｎｅｎｓｅ 二亲本及Ｆ１杂种花粉母细胞减数分裂终变期和中期Ⅰ期染色体配对的构型。结果表明;二亲本工粉母细胞减娄分裂染色体配对均正常,为１２个二价体。Ｆ１杂种花粉母细胞减数分裂染色体配对很不规则。其平均频率为单价体０．０３６,二价体９．１８,三价体０．０３６,四价体０．８０,六价体０．３８。     

Nonstructural Chromosome Differentiation among Wheat Cultivars, with Special Reference to Differentiation of Chromosomes in Related Species

Wheat cultivar Chinese Spring (Triticum aestivum L. em. Thell.) was crossed with cultivars Hope, Cheyenne and Timstein. In all three hybrids, the frequencies of pollen mother cells (PMCs) with univalents at metaphase I (MI) were higher than those in the parental cultivars. No multivalents were observed in the hybrids, indicating that the cultivars do not differ by translocations. Thirty-one Chinese Spring telosomic lines were then crossed with substitution lines in which single chromosomes of the three cultivars were substituted for their Chinese Spring homologues. The telosomic lines were also crossed with Chinese Spring. Data were collected on the frequencies (% of PMCs) of pairing of the telesomes with their homologues at MI and the regularity of pairing of the remaining 20 pairs of Chinese Spring chromosomes in the monotelodisomics obtained from these crosses. The reduced MI pairing in the intercultivar hybrids was caused primarily by chromosome differentiation, rather than by specific genes. Because the differentiation involved a large part of the chromosome complement in each hybrid, it was concluded that it could not be caused by structural changes such as inversions or translocations. In each case, the differentiation appeared to be unevenly distributed among the three wheat genomes. It is proposed that the same kind of differentiation, although of greater magnitude, differentiates homoeologous chromosomes and is responsible, together with structural differentiation, for poor chromosome pairing in interspecific hybrids.     

Distribution of Nonstructural Variation along Three Chromosome Arms between Wheat Cultivars Chinese Spring and Cheyenne

Metaphase I (MI) pairing of wheat homologous chromosomes is usually reduced in hybrids between cultivars relative to the parental inbred lines. Previous work suggested that this phenomenon is caused by polymorphism in nucleotide sequences (nonstructural chromosome variation) among wheat cultivars. The present work investigated the distribution of this variation along three selected chromosome arms between cultivars Chinese Spring and Cheyenne. Chinese Spring ditelosomics 3Aq, 6Ap and 6Bp were crossed with disomic substitutions of Cheyenne chromosomes 3A, 6A and 6B in Chinese Spring, respectively. The resulting F₁ plants, called substituted monotelodisomics, were crossed with the respective Chinese Spring monosomics, producing potentially "recombinant" substituted monosomics. When these "recombinant" chromosomes were combined with the parental Chinese Spring telosomes, marked reductions in mean telosome-pairing frequency were found compared with the corresponding Chinese Spring monotelodisomics. The mean pairing frequencies of the "recombinant" chromosomes showed a continuous distribution between those of the substituted and Chinese Spring monotelodisomics. The results suggest that the nonstructural variation that reduces MI pairing between chromosomes of different wheat cultivars is not localized in a specific site but distributed along each chromosome arm. Little variation was found among monotelodisomics for either the number of ring bivalents per cell or the number of univalents other than those constituting the heteromorphic pair. This implies that the reductions in MI pairing between the Cheyenne and Chinese Spring chromosomes are caused by something residing within these specific chromosomes that does not affect the pairing of the remaining Chinese Spring chromosomes in the same cell. Furthermore, the absence of parental types among the "recombinant"-substituted monotelodisomics suggests that the sequences involved in the variation studied here are capable of converting heterohomologous chromosomes to something intermediate in nature in the span of only a single generation.     

Cytogenetic studies on two F1 hybrids of autotetraploid rice varieties showing extremely high level of heterosis

Mechanisms of two F1 hybrids (D46A × DTP-4 and D46A × Dminghui63) of autotetraploid rice (2n = 4x = 48) showing extremely high pollen fertility 87.40% and 85.97%, respectively, seed set 82.00% and 79.00%, respectively and extremely high level of heterosis were analyzed cytologically. The chromosome pairing of D46A × DTP-4 and D46A × Dminghui63 was normal at metaphase I(MI), and had almost no I or III, with an average of 0.020I +14.36 II 6.44rod+7.91ring) +0.01III + 4.80 IV + 0.01VIII and 0.06 I + 17.67 II (11.01rod + 6.67ring)] + 0.06 III +3.10IV+0.01VI, respectively. The most frequent chromosome configurations were 10II+7IV and 12II+bIV. The bivalent frequency was less frequent in hybrids than that in restoring parents, and the same results were gained from univalents, trivalent and multivalents. However, the quadrivalent frequency was significantly higher in hybrids than that in restoring parents at MI. The other meiotic phases progressed normally, except for low percentages of PMCs with lagging chromosomes at AI and low percentages of PMCs with micronuclei at telophaseI (TI) and telophaseII (TII). PMCs with lagging chromosomes at AI and PMCs with micronuclei at TI and TII showed negative correlation between pollen fertility and seed set. Above 90% of the PMCs could form normal microspores, which resulted in the production of viable pollen grains, abnormal microspores were observed including penta-fission and hexa-fission. Based on these results we suggest that the two F1 hybrids had better behaviors of chromosome pairing and genetic stability than autotetraploid rice and other autotetraploid plants ever studied.     

Distribution of Nonstructural Variation between Wheat Cultivars along Chromosome Arm 6Bp: Evidence from the Linkage Map and Physical Map of the Arm

Metaphase I (MI) pairing of homologous chromosomes in wheat intercultivar hybrids (heterohomologous chromosomes) is usually reduced relative to that within the inbred parental cultivars (euhomologous chromosomes). It was proposed elsewhere that this phenomenon is caused by polymorphism in nucleotide sequences (nonstructural chromosome variation) among wheat cultivars. The distribution of this polymorphism along chromosome arm 6Bp (=6BS) of cultivars Chinese Spring and Cheyenne was investigated. A population of potentially recombinant chromosomes derived from crossing over between telosome 6Bp of Chinese Spring and Cheyenne chromosome 6B was developed in the isogenic background of Chinese Spring. The approximate length of the Chinese Spring segment present in each of these chromosomes was assessed by determining for each chromosome the interval in which crossing over occurred (utilizing the rRNA gene region, a distal C-band and the gliadin gene region as markers). The MI pairing frequencies of these chromosomes (only the complete chromosomes were used) with the normal Chinese Spring telosome 6Bp were determined. These were directly proportional to the length of the euhomologous segment. The longer the incorporated euhomologous segment the better was the MI pairing. This provided evidence that the heterohomologous chromosomes are differentiated from each other in numerous sites distributed throughout the arm.—The comparison of the physical map of arm 6Bp with the linkage map showed a remarkable distortion of the linkage map; no crossing over was detected in the proximal 68% of the arm. A population of 49 recombinant chromosomes was assayed for recombination within the rRNA gene region, but none was detected. No new length variants of the nontranscribed spacer separating the 18S and 26S rRNA genes were detected either.     

普通小麦与鹅观草属间杂种F1及BC1的分子细胞遗传学、育性和赤霉病抗性研究

通过胚拯救, 成功获得鹅观草Roegneria kamoji (2n=6x=42, SSHHYY)和普通小麦中国春Triticum aesti-vum (2n=6x=42, AABBDD)的正反交属间杂种F1, 并对这些杂种F1及其BC1的形态学、减数分裂配对行为、育性和赤霉病抗性进行研究。结果表明, (鹅观草×中国春)F1和(中国春×鹅观草)F1的形态介于双亲之间。杂种F1花粉母细胞减数分裂中期I染色体构型分别为40.33I + 0.78II + 0.03III和40.40I + 0.79II 。杂种F1高度雄性不育, 用中国春花粉与其回交可获得BC1代种子。(鹅观草×中国春) F1×中国春BC1植株的染色体数目主要分布在55~63之间, 单价体较多, 植株高度不育; (中国春×鹅观草)F1×中国春BC₁植株染色体数目也主要分布在55~63之间, 但其中部分植株拥有整套小麦染色体且能正常配对、分离, 可形成部分可育花粉粒, 能收到少量自交结实种子。在 (鹅观草×中国春)F1中有1株穗型趋向中国春, 其染色体数目为2n=63, 经染色体分子原位杂交(GISH)检测, 含有42条小麦染色体和21条鹅观草染色体。该杂种F1在减数分裂中期I平均每个花粉母细胞有26.40I+18.30II, 但植株高度雄性不育, 用中国春花粉回交能收到BC₁种子。(鹅观草×中国春) F₁ (2n=63)×中国春BC₁的染色体数目主要分布在40~59之间, 其中的外源染色体已经逐渐减少, 虽然该BC₁的穗型已接近中国春, 但仍然高度不育。赤霉病抗性鉴定结果显示, 所有杂种F1及大部分BC₁对赤霉病均表现出较好的抗性。     

普通小麦与鹅观草属间杂种F1及BC1的分子细胞遗传学、育性和赤霉病抗性研究

通过胚拯救, 成功获得鹅观草Roegneria kamoji (2n=6x=42, SSHHYY)和普通小麦中国春Triticum aesti-vum (2n=6x=42, AABBDD)的正反交属间杂种F1, 并对这些杂种F1及其BC1的形态学、减数分裂配对行为、育性和赤霉病抗性进行研究。结果表明, (鹅观草×中国春)F1和(中国春×鹅观草)F1的形态介于双亲之间。杂种F1花粉母细胞减数分裂中期I染色体构型分别为40.33I + 0.78II + 0.03III和40.40I + 0.79II 。杂种F1高度雄性不育, 用中国春花粉与其回交可获得BC1代种子。(鹅观草×中国春) F1×中国春BC1植株的染色体数目主要分布在55~63之间, 单价体较多, 植株高度不育; (中国春×鹅观草)F1×中国春BC₁植株染色体数目也主要分布在55~63之间, 但其中部分植株拥有整套小麦染色体且能正常配对、分离, 可形成部分可育花粉粒, 能收到少量自交结实种子。在 (鹅观草×中国春)F1中有1株穗型趋向中国春, 其染色体数目为2n=63, 经染色体分子原位杂交(GISH)检测, 含有42条小麦染色体和21条鹅观草染色体。该杂种F1在减数分裂中期I平均每个花粉母细胞有26.40I+18.30II, 但植株高度雄性不育, 用中国春花粉回交能收到BC₁种子。(鹅观草×中国春) F₁ (2n=63)×中国春BC₁的染色体数目主要分布在40~59之间, 其中的外源染色体已经逐渐减少, 虽然该BC₁的穗型已接近中国春, 但仍然高度不育。赤霉病抗性鉴定结果显示, 所有杂种F1及大部分BC₁对赤霉病均表现出较好的抗性。     

萝卜与甘蓝属间杂种基因组原位杂交分析

用基因组原位杂交方法（Genomic in situ hybridization, 简称GISH）研究了萝卜( Raphanus sativus,2n=18,RR)和甘蓝（Brassica oleracea , 2n=18, CC）属间杂种F1减数分裂过程。结果表明杂种体细胞染色体组成为RC,2n=18,但花粉母细胞有三种不同类型：1. RC,2n=18, 终变期染色体平均配对构型为14.87Ⅰ+1.20Ⅱ+0.04Ⅲ+0.06Ⅳ, 染色体配对主要发生在萝卜和甘蓝染色体之间, 后期Ⅰ9条萝卜染色体主要以5/4和6/3的分离比移向两极, 所形成配子的染色体数目和组成均不平衡,配子败育; 2. RRCC,4n=36, 终变期染色体形成18个二价体,后期Ⅰ染色体均衡分离,形成RC不减数配子;3. RRCC缺体,4n=30－34, 少数萝卜染色体丢失,形成的配子具有全套的甘蓝染色体和部分萝卜染色体。     

phlb基因诱导小麦ABD染色体组部分同源染色体配对的研究

通过花药培养首次获得了“中国春”phlb突变体单倍体,同时也获得了“中国春”单倍体。对其细胞学观察表明,前者花粉母细胞减数分裂中期Ⅰ每个细胞染色体交叉为5.08个,后者为1.30个。证明了phlb基因在单倍体状态下具有强的诱导ABD染色体组部分同源染色体间的配对作用。     

Latent Nonstructural Differentiation among Homologous Chromosomes at the Diploid Level: Chromosome 6B of AEGILOPS LONGISSIMA

Previous work has shown that chromosome pairing at metaphase I (MI) of wheat homologous chromosomes from different inbred lines (heterohomologous chromosomes) is reduced relative to that between homologous chromosomes within an inbred line (euhomologous chromosomes). In order to determine if a potential for this phenomenon exists in diploid species closely related to the wheat B genome, MI chromosome pairing was investigated between euhomologous and heterohomologous 6B^e (=6S^e) chromosomes, each from a different population of Aegilops longissima Schweinf. et Muschl. (2n = 2x = 14) substituted for chromosome 6B of Chinese Spring wheat (Triticum aestivum L., 2n = 6x = 42). Euhomologous and heterohomologous monotelodisomics, i.e., plants with one complete chromosome 6B^e and a telosome of either 6B^ep or 6B^eq, were constructed in the isogenic background of Chinese Spring. Pairing at MI of the Ae. longissima chromosomes was reduced in heterohomologous monotelodisomics compared to that in the corresponding euhomologous monotelodisomics. The remaining 20 pairs of Chinese Spring chromosomes paired equally well in the euhomologous and heterohomologous monotelodisomics. Thus, the cause of the reduced pairing must reside specifically in the Ae. longissima heterohomologues. In the hybrids between the Ae. longissima lines that contributed the substituted chromosomes, pairing between the heterohomologous chromosomes was normal and did not differ from that of the euhomologous chromosomes. These data provide evidence that a potential for reduced pairing between the heterohomologues is present in the diploid species, but is expressed only in the polyploid wheat genetic background. The reduction in heterohomologous chromosome pairing was greater in the p arm than in the q arm, exactly as in chromosome 6B of wheat. It is concluded that the reduced pairing between Ae. longissima heterohomologues has little to do with constitutive heterochromatin. The value of chromosome pairing as an unequivocal means of determining the origin of genomes in polyploid plants is questioned.