鹅观草属——人工合成双二倍体(2n=10x=70)的细胞学及育性的研究

本文对缘毛鹅观草（Roegneria pendulina）、鹅观草（R.tsukushiensis var.transiens）及其人工合成杂种F1、双二倍体进行了细胞学,育性等的分析和研究。结果表明双亲的减数分裂,花粉育性和结实性均正常,杂种F1的减数分裂不规则且完全不育;当代双二倍体的染色体数目为70,其减数分裂构型为:6.04 Ⅰ+26.21 Ⅱ+1.52 Ⅲ+1.59 Ⅳ+0.02 Ⅴ:第二代双二倍体的染色体数目为70,个别植株为69,减数分裂构型分别为:4.16 Ⅰ+27.33 Ⅱ+0.50 Ⅲ+2.16 Ⅳ和4.79 Ⅰ26.26 Ⅱ+1.13 Ⅲ+2.13 Ⅳ。与期望染色体配对模式相比,双二倍体中二价体出现的频率有明显增大的趋势。在减数分裂AⅠ和AⅡ分别观察到数目不定的落后单价体,大部份的四分体中出现了微核。双二倍体的育性得到了很大程度的恢复,其花粉可染色性及结实率分别为54.4％和64.0％。     

鹅观草×黑麦杂种F_1的形态及细胞遗传学研究

以鹅观草作母本,黑麦作父本进行杂交,采用杂种幼胚培养技术,首次成功地获得了F_1杂种。杂种穗形呈双亲的中间类型,完全雄性不育。花粉母细胞减数分裂中期在Ⅰ平均染色体配对构型为:27.01Ⅰ+0.47Ⅱ+0.02Ⅲ,后期Ⅰ形成大量的落后染色体以及发生不均等的两极分裂和多极分裂,进而形成多分体。花粉粒发育过程中出现不同数目的微核。     

纤毛鹅观草同阿拉善鹅观草、大丛鹅观草间杂种细胞学研究

为了探索阿拉善鹅观草RoegneriaalashanicaKeng、大丛鹅观草RoegneriamagnicaespesD .F .Cui与纤毛鹅观草Roegneriaciliaris (Trin .)Nevski间的相互关系 ,将其进行了远缘杂交 ,通过幼胚离体培养 ,两个组合均成功合成了杂种。对亲本及杂种F1 花粉母细胞减数分裂中期Ⅰ染色体配对行为及形态学进行了统计分析。结果表明 ,上述物种的种间杂交较难进行 ,杂种F1 减数分裂染色体平均构型分别为 :R ciliaris×R alashanica 10 6 2Ⅰ 8 17Ⅱ 0 32Ⅲ 0 0 2Ⅳ (c -值 =0 4 4 ) ,R ciliaris×R magnicaespes 18 0 0Ⅰ 4 76Ⅱ 0 16Ⅲ (c -值 =0 2 1) ;杂种穗部特征多数介于双亲之间。阿拉善鹅观草、大丛鹅观草与纤毛鹅观草间至少有一个基因组具有较高的同源性 ,即为S基因组 ,本文对它们在分类中的地位也进行了讨论。     

鹅观草与大鹅观草杂种的细胞遗传学及形态学研究

大鹅观草（ Ｒｏｅｇｎｅｒｉａ ｇｒａｎｄｉｓ Ｋｅｎｇ） 是分布于我国陕西的一种多年生四倍体植物。为了探索大鹅观草与鹅观草（ Ｒｏｅｇｎｅｒｉａ ｋａｍｏｊｉ Ｏｈｗｉ） 间的物种生物学关系, 通过对其进行远缘杂交,幼胚离体培养, 合成了远缘杂种; 并对亲本及杂种Ｆ１ 代花粉母细胞减数分裂中期Ⅰ染色体配对行为及形态学进行了研究。结果表明杂种Ｆ１ 减数分裂染色体配对平均构型为： Ｒ－ ｋａｍｏｊｉ ×Ｒ－ｇｒａｎｄｉｓ１０－２６ Ⅰ＋ １２－３７ Ⅱ（ｃ－ 值＝ ０－７４） , 大鹅观草与鹅观草所含的ＳＹ 染色体组间存在较大的同源性分化; 杂种穗部特征大多数介于双亲之间。     

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。     

大鹅观草与阿拉善鹅观草杂种的形态学和细胞学研究

为探讨阿拉善鹅观草 ( R.alashanica( Keng) S.L.Chen)的染色体组组成 ,进行了大鹅观草 ( R.grandisKeng( 2 n=2 4 ,St St YY) )和阿拉善鹅观草种间杂交 ,对这两个种及其杂种 F1的形态学、繁育学和减数分裂染色体配对行为进行了研究。结果表明 :杂种 F1的形态特征介于父母本之间 ,其花粉母细胞减数分裂染色体平均构型为 :2 0 .4 0 +3.6 9 +0 .0 9 +0 .0 4 。表明阿拉善鹅观草含有一个修饰的 St基因组 ,即 Sta。     

普通小麦与簇毛麦双二倍体的合成,育性及细胞遗传学研究

通过杂种幼胚无性系培养获得大量再生植株F_1,经秋水仙碱处理,合成了普通小麦与簇毛麦属间双二倍体(AABBDDVV)。其形态特征除株高、穗长、小穗数,籽粒大小和育性明显增加,生育期延长外,分别与各自的再生植株F_1相似。双二倍体的体细胞染色体数目变化范围为48—56。花粉母细胞减数分裂中期Ⅰ 2n=28Ⅱ的细胞占56.82％,每个细胞平均有27.10个二价体,1.44个单价体,0.08个三价体,0.03个四价体。经过连续两代单穗单株选择,结实率由15.91％提高到36.52％。     

华山新麦草和鹅观草属两个种间物种生物学研究

通过华山新麦草（２ｎ＝１４,ＮＮ）和鹅观草属的两个种（纤毛鹅观草（２ｎ＝２８ ＳＹ）和鹅观草（２ｎ＝４２ ＳＨＹ）属间杂交,两个组合均得到生长健壮的植株。杂种Ｆ１形态上均为双亲的中间型。纤毛鹅观草Ｘ华山新麦草和鹅观草Ｘ华山新麦草杂种Ｆ１染色体配对构型分别为：２０．７３Ｉ＋０．３１８Ⅱ,２４．８０１Ⅰ＋１．５７Ⅱ＋０．０１２Ⅲ。后期Ⅰ均出现多极分离。两个组合均发现减数分裂过程异常现象。两个组合染色体     

鹅观草x黑麦杂种F，的形态及细胞遗传学研究

以鹅观草作母本,黑麦作父本进行杂交,采用杂种幼胚培养技术,首次成功地获得了F,杂种。杂种 穗形呈双亲的中间类型,完全雄性不育。花粉母细胞减数分裂中期I平均染色体配对构型为：27.011+ 0.4711＋0.01111,后期I形成大量的落后染色体以及发生不均等的两极分裂和多极分裂,进而形成多 分体。花粉粒发育过程中出现不同数目的微核。     

5个菊花品种自交结实特性及减数分裂行为与花粉育性研究

对rm1-1、rm1-3、02-42-6、rm1-4和rm48-2等5个菊花品种3年自交结实率及花粉母细胞的减数分裂行为和花粉活力进行了研究.结果显示:(1)rm1-1、rm1-3和02-42-6属自交结实品种,结实性主要来源筒状小花;rm1-4和rm48-2为自交不结实品种.(2)在减数分裂过程中,rm1-1、rm1-3和02-42-6中期Ⅰ每个花粉母细胞(PMC)平均染色体配对构型分别为0.93Ⅰ+23.64Ⅱ+0.85Ⅲ+0.64Ⅳ、0.92Ⅰ+ 24.40Ⅱ+ 0.78Ⅲ+0.51Ⅳ和0.45Ⅰ+ 25.04Ⅱ+0.36Ⅲ+0.55Ⅳ;rm1-4和rm48-2每个PMC平均染色体配对构型分别为0.53Ⅰ+25.25Ⅱ+0.84Ⅲ+0.16Ⅳ和1.39Ⅰ+24.87Ⅱ+0.42Ⅲ+0.40Ⅳ;后期和末期5个品种花粉母细胞均出现不同频率的染色体桥、落后染色体、微核等异常现象,但大部分花粉母细胞均能正常发育.(3)5个品种花粉萌发率为8.1%～28.9%,其中rm1-1最低,rm1-4最高.结果表明,减数分裂过程和花粉育性与自交结实率没有必然关系.     

Aberrant microspore development in hybrids of maize x Tripsacum dactyloides.

Cytogenetic investigations of meiosis in hybrids between maize and Tripsacum have been well documented; however, the inherent problem of male and female sterility has not been addressed either on a genetic or cytogenetic level. The purpose of this cytological study was to identify some of the probable causes of male sterility in maize x Tripsacum dactyloides hybrids. Disturbances in pollen development of maize x T. dactyloides hybrids, derived from both diploid (2n) and tetraploid (4n) Tripsacum sources, were commonly observed. Anomalies in the development of the microspore apparently occurred because of a failure of the chromosomes to congregate at the metaphase plate, development of a tripolar spindle, and failure of cytokinesis at the first and second meiotic divisions. Phenotypic features of abnormal microspore development were the maturation of large pollen grains, "Siamese" pollen grains, the occurrence of variable invaginations, and a nuclear budding-type behavior. These abnormalities were not observed in the 56-chromosome amphidiploid or the 38-chromosome backcross generations.     

Cytogenetic analysis of Lycopersicon esculentum (+) Solanum etuberosum somatic hybrids and their androgenetic regenerants

The aim of the study was to characterize genomic relationships among cultivated tomato (Lycopersicon esculentum Mill.) (2n=2x=24) and diploid (2n=2x=24) non-tuberous wild Solanum species (S. etuberosum Lindl.). Using genomic in situ hybridization (GISH) of mitotic and meiotic chromosomes, we analyzed intergeneric somatic hybrids between tomato and S. etuberosum. Of the five somatic hybrids, two plants were amphidiploids (2n=4x=48) mostly forming intragenomic bivalents in their microsporocytes, with a very low frequency of multivalents involving the chromosomes of tomato and S. etuberosum (less than 0.2 per meiocyte). Tomato chromosomes showed preferential elimination during subsequent meiotic divisions of the amphidiploids. Transmission of the parental chromosomes into microspores was also evaluated by GISH analysis of androgenic plants produced by direct embryogenesis from the amphidiploid somatic hybrids. Of the four androgenic regenerants, three were diploids (2n=2x=24 or 2n=2x+1=25) derived from reduced male gametes of the somatic hybrids, and one plant was a hypertetraploid (2n=4x+4=52). GISH revealed that each anther-derived plant had a unique chromosome composition. The prospects for introgression of desirable traits from S. etuberosum into the gene pool of cultivated tomato are discussed. Received: 2 August 2000 / Accepted: 4 December 2000     

Reproduction and cytogenetic characterization of interspecific hybrids derived from Cucumis hystrix Chakr. x Cucumis sativus L

Interspecific hybrids between Cucumis hystrix Chakr. (2n = 2 x = 24) and Cucumis sativus L. (2n = 2 x = 14) were produced by means of F(1) (2n = 19) embryo rescue and subsequent chromosome doubling. The hybridity was confirmed by genomic in situ hybridization (GISH) and chromosome analysis. The amphidiploid (2n = 38) was self-pollinated and backcrossed to cucumber resulting in lines with improved crossability to C. sativus. Examination of shape, stainability, and germination rate of pollen grains and yield as a function of mature fruit set per ten pollinated flowers indicated a tendency for increased fertility in BC(1)S(1) progeny when compared to F(1) and amphidiploid offspring. Cytogenetic characterization of F(1) and amphidiploid progeny was performed. Generally normal meioses produced viable pollen grains, and fertilization resulted in partial fertility restoration in amphidiploid progeny. Chromosome anomalies such as "frying-pan trivalent", chromosome lagging and spindle mis-orientation were also observed. In most of the PMCs of the F(1) diploid hybrid progeny, 19 univalents were observed at diakinesis and MI. In the amphidiploid, more than 90% of the configurations at MI consisted of the predicted 19 bivalents and less than 5% contained multivalents [trivalents (2.3%) + quadrivalents (0.3%)], suggesting the presence of preferential pairing, and a distinctive parental genome as well. The chiasmata observed between homoeologous chromosomes further demonstrated the introgression of the C. hystrix genome into that of C. sativus.     

Cytological investigations of the interspecific hybrids of Nicotiana tabacum L. x N. glauca Grah

Interspecific amphihaploid and amphidiploid hybrids between Nicotiana glauca Grah. (2n = 24) and N. tabacum L. (2n = 48) cultivars BY 103 and K 326 were analysed. F1 amphihaploids (2n = 36) were viable and completely self- and cross-sterile, and mostly univalents were present during meiosis (with pairing range from 0 to 5). In some meiocytes, meiotic irregularities were observed, such as sporadic chromatin bridges and formation of restitution nuclei. The resultant F1 hybrids were easily converted to amphidiploids (2n = 72) via colchicine treatment of seedlings. The number of univalents and the frequency of PMCs containing unpaired chromosomes indicated that amphidiploids N. tabacum cv. BY 103 or K 326 x N. glauca represented quite a high pairing category. However, they were male sterile because pollen mother cells were arrested at the tetrad stage. The termination of development of PMCs, and consequently male sterility, are very rare in this kind of tobacco hybrids.     

A comparative cytogenetic study of the rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) autotetraploid restorers and hybrids

We studied pollen fertility, seed set and cytogenetic characteristics of restorer lines and F1 hybrids of autotetraploid rice. T4002, T4063, T461A × T4002 and T461A × T4063 showed significantly higher pollen fertility and seed set than T4132 and T461A × T4132. Meiotic pairing configurations of T4002, T4063, T4132, T461A × T4002, T461A × T4063 and T461A × T4132 were 0.05 I + 19.96 II (9.89 rod + 10.07 ring) + 0.01 III + 2.00 IV, 0.11 I + 19.17 II (8.90 rod + 10.37 ring) + 0.09 III + 2.26 IV + 0.01 VI, 1.34 I + 9.46 II (4.50 rod + 4.96 ring) + 0.80 III + 6.02 IV + 0.09 VI + 0.09 VIII, 0.02 I + 14.36 II (6.44 rod + 7.91 ring) + 0.01 III + 4.80 IV + 0.01 VIII, 0.06 I + 17.67 II (11.01 rod + 6.67 ring) + 0.06 III + 3.10 IV + 0.01 VI and 1.11 I + 11.31 II (5.80 rod + 5.51 ring) + 0.41 III + 5.63 IV + 0.03 VI + 0.03 VIII, respectively. Configuration 16 II + 4 IV and 12 II + 6 IV occurred in the highest frequency among the autotetraploid restorers and hybrids. Meiotic chromosome behaviors were less abnormal in the tetraploids with high seed set than those with low seed set. The hybrids had fewer frequencies of bivalents, univalents, trivalents and multivalents than the restorers, but higher frequency of quatrivalents than the restorers at MI. The frequency of univalents at MI had the most impact on pollen fertility and seed set, i.e., pollen fertility decreased with the increase of univalents. The secondary impact factors were trivalents and multivalents, and bivalents and quatrivalents had no effect on pollen fertility and seed set. The correlative relationship between pollen fertility and cytogenetic behaviors could be utilized to improve seed set in autotetraploidy breeding.     

四个栽培棉种间的杂种F1细胞遗传学与亲缘关系研究

以棉属四个栽培棉种进行种间杂交,产生(亚洲棉×草棉)和(陆地棉×海岛棉)2个二元杂种F1及其[(亚洲棉×草棉)×(陆地棉×海岛棉)]四元杂种F1,观察和测定4个栽培棉种及其2个二元杂种F1和四元杂种F1的花粉母细胞(PMC)减数分裂的染色体行为及其花粉生活力,以研究4个栽培棉种间的亲缘关系和进化关系。结果表明,二元杂种(亚洲棉×草棉)F1的PMC减数分裂中期Ⅰ出现一个四体环,其余为二价体,染色体构型为2n=26=11Ⅱ 1Ⅳ;花粉生活力的测定表明,(亚洲棉×草棉)F1可育型花粉为50.71%,表现为典型的配子半不育特性,说明两个二倍体棉种间发生一次染色体易位。(陆地棉×海岛棉)F1以26个二价体细胞为主,但有少量的单价体、三价体以及四价体,染色体构型为2n=52=0.78Ⅰ 22.24Ⅱ 0.94Ⅲ 0.98Ⅳ。花粉生活力的测定表明,(陆地棉×海岛棉)F1可育型花粉为54.84%,可见2个四倍体棉种间亲缘关系较近,二者之间仅发生了染色体的易位或倒位。而由4个栽培种合成的四元杂种F1,其减数分裂异常,染色体丢失现象普遍,部分染色体不能联会配对,以单价体的形式存在,并出现三价体、四价体、五价体等多价体,染色体构型为2n=52=5.45Ⅰ 14.41Ⅱ 2.44Ⅲ 1.59Ⅳ 0.63Ⅴ 0.15Ⅵ,其可育花粉为6.87%。研究结果表明了4种栽培棉种之间的亲缘关系相对较近,可以通过遗传重组产生综合有4个栽培棉种性状的新种质。     

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.     

Synthesis, morphology and cytogenetics of Raphanofortii (TTRR, 2n = 38): a new amphidiploid of hybrid Brassica tournefortii (TT, 2n = 20) ×Raphanus caudatus (RR, 2n=18)

Amphidiploid Raphanofortii was synthesized by colchicinization of the F₁ hybrid Brassica tournefortii (TT, 2n = 20)×Raphanus caudatus (RR, 2n = 18). The crossability between these two species, and the cytomorphology of the F₁ plants and the amphidiploids were investigated. Intergeneric hybrids between the species were obtained only when B. tournefortii was involved as female parent. The hybrid plants were intermediate for most of the morphological attributes and showed very low pollen fertility compared to the parents. Although a majority of the pollen mother cells of the dihaploid hybrid (TR, 2n = 19) harboured univalents, a maximum of six bivalents were also observed. Of the 37 colchicine-treated F₁ plants analyzed cytologically, 21 were found to be true amphidiploids (2n = 38), whereas seven were mixoploids. Meiosis in the amphidiploids was characterized by the occurrence of 19 bivalents, though multivalents and univalents were also observed in a few cells. Most of the amphidiploid plants exhibited a fairly high pollen and seed fertility, which was further enhanced with the advancement of generations. Out of 69 plants investigated in the A₂ generation, 64 were euploids while the remaining five were aneuploids (2n = 36, 37, 39, 40 and 42). The newly synthesized Raphanofortii has great potential as a new commercial crop, as well as a bridge species for the transfer of economically important attributes of both the species to other Brassicas. Received: 2 November 1999 / Accepted: 26 March 2000     

加拿大披碱草和圆柱披碱草BC1植株的细胞遗传学鉴定

以加拿大披碱草(2n=4x=28)和圆柱披碱草(2n=6x=42)为材料,对其BC1植株染色体数目、配对构型以及花粉育性和结实性等进行了鉴定。结果显示:BC1代85%以上细胞染色体数目为28条(2n=4x=28);BC1植株的花粉母细胞减数分裂中期Ⅰ染色体配对行为较规则,其平均染色体构型分别为0.04Ⅰ 13.98Ⅱ,且环状二价体多于棒状二价体;BC1植株的花粉可育率和自然结实率分别为84.83%和70.98%,说明BC1植株的育性已得到恢复,为其后代优良株系的选育奠定了基础。     

Cytological Studies of Hybrids of Roegneria ciliaris with R.alashanica and R.magnicaespes(Poaceae:Triticeae)

In order to investigate the relationships between Roegneria.ciliaris(Trin.)Nevski and R.alashanica Keng,and between R.ciliaris and R.magnicaespes D.F.Cui.R.ciliaris(Trin.)Nevski was crossed with the other two species,through the aid of embryo rescue. Hybrids were obtained from these two combinations.Chromosome pairing behavior of parents an dhybrids was observed at metaphase I of pollen mother cells. Meiotic configuratons were 10.62Ⅰ＋8.17Ⅱ＋0.32Ⅲ＋0.02Ⅳ for R.ciliaris×R.magnicaespes and 18.00Ⅰ＋4.76Ⅱ＋0.16Ⅲ for R.ciliaris ×R.magnicaespes;c-value of the two hybrids were 0.44 and 0.21,respectively.