鹅观草和簇毛麦属间杂种的形态学和细胞遗传学研究

通过幼胚离体拯救培养,成功地获得鹅观草Roegneria kamoji Ohwi(2n=6x=42,StStHHYY)和 簇毛麦Dasypyrum villosum(L．)Candargy(2n=2x=14,VV)属间杂种,对这两个种及其杂种F_l的形 态学、繁育学和减数分裂配对行为进行了研究。结果表明：(1)鹅观草和簇毛麦形态差异极大,杂种F1 的形态特征介于父母本之间;(2)杂交结实率低,为11．63％;经幼胚组织培养,获2株杂种苗;杂种F_l高 度不育,表明亲本间存在极强的生殖隔离,是独立的生物学种;(3)杂种F_l体细胞染色体数目为稳定的 28条,减数分裂中期I染色体配对很低,其构型为：26．72Ⅰ+0．62Ⅱ+0．02Ⅲ。表明鹅观草的St、H、Y染色体组与簇毛麦的V染色体组部分同源性很低,它们的亲缘关系较远。     

节节麦和硬粒小麦-簇毛麦双二倍体间杂种的产生及其细胞遗传学研究

通过胚培养产生了节节麦和硬粒小麦-簇毛麦双二倍体间的杂种。结果表明节节麦和硬粒小麦-簇毛麦双二倍体杂交以节节麦作母本较易结实,3个组合的结实率分别为59.18%、67.72%和60.22%,胚培成苗率分别为39.13%、38.10%和50%。杂种F_1生活力旺盛,形态像父本硬粒小麦-簇毛麦双二倍体。杂种自交可孕,3个组合自交结实率平均为7.63%。杂种F_1(ABVD)的减数分裂平均构型为25.36个单价体,1.21个二价体和0.06个三价体,平均每个细胞交叉结频率为1.38,高于“中国春”单倍体的配对频率,推测V组和A、B、D组染色体间有部分同源关系。节节麦和硬粒小麦-簇毛麦双二倍体杂交可能是产生八倍体(AABBDDVV)的又一途径。     

辣椒属种间杂种F_1植株的细胞遗传学研究

本文分析了南京早椒（ＣａｐｓｉｃｕｍｆｒｕｔｅｓｃｅｎｓＬ．ｖａｒ．ＣｏｎｏｉｄｅｅｓＢａｉｌｅｙ）和Ｃ．ｃｈｉｎｅｎｓｅ二亲本及Ｆ１杂种花粉母细胞减数分裂终变期和中期Ｉ染色体配对的构型。结果表明：二亲本花粉母细胞减数分裂染色体配对均正常,为１２个二价体（双单倍体２ｎ＝２４）。Ｆ１杂种花粉母细胞减数分裂染色体配对很不规则。其平均频率分别为单价体０．０３６,二价体９．１８,三价体０．０３６,四价体０．８０,六价体０．３８。南京早椒和Ｃ．ｃｈｉｎｅｎｓｅ染色体间存在着相互易位,因此,二亲本间彼此有差异。单价体出现极少,这可断定南京早椒与Ｃ．ｃｈｉｎｅｎｓｅ染色体间是部分同源的,但染色体组结构上存在着差异。由于染色体结构上差异,所以Ｆ１杂种的育性较低。     

大鹅观草与蛇河披碱草属间杂种的细胞遗传学研究

为探讨大鹅观草(Roegneria grandis,2n=4x=28)的染色体组组成,为其正确的分类处理提供细胞学依据。该研究通过人工远缘杂交,成功获得3株大鹅观草与蛇河披碱草(Elymus wawawaiensis,2n=4x=28)属间杂种F1植株。杂种植株形态介于两亲本之间,不育。亲本及杂种经I2-IK溶液染色后进行花粉育性检测,结果显示Roegneria grandis和Elymus wawawaiensis的花粉可育,育性高达94.6%和90.5%;杂种F1不育。花粉母细胞减数分裂中期I染色体配对结果显示,亲本花粉母细胞配对正常,均形成14个二价体,以环状二价体为主,Roegneria grandis有频率很低(0.04/细胞)的单价体出现;杂种F1平均每个花粉母细胞形成6.46个二价体,变化范围为5~8;在观察的83个花粉母细胞中,有35.2%的花粉母细胞形成了7个二价体,形成6个二价体的细胞占42.59%,较少细胞形成8个二价体;平均每个细胞形成14.66个单价体,变化范围为10~18;平均每细胞观察到0.14个三价体;杂种花粉母细胞染色体构型为14.66 I+6.46 II+0.14 III;平均每细胞交叉数为9.83,C值为0.35。结果表明:(1)R.grandis与Elymus wawawaiensis有一组染色体组同源的St染色体组,另外一组染色体组不是St或者H染色体组,Roegneria grandis的染色体组组成不是St Stg;(2)较低频率的三价体(平均0.14个/细胞),可能是由于R.grandis的St和Y染色体组间具有一定的同源性,也可能是染色体易位等原因导致,对于Y染色体组的起源还需深入地研究;(3)在不同地理来源的披碱草属和鹅观草属物种中St染色体组同源性不同,R.grandis与来自于北美的Elymus lanceolatus与E.wawawaiensis的St染色体组较与分布于亚洲的E.sibiricus和E.caninus的St染色体组同源性反而更高,其原因还需要进一步地研究。     

大麦与小麦属间杂种的形态学和细胞遗传学研究

通过幼胚培养技术分别获得了大麦(Hordeum vulgare L., 2n=2x=14)与普通小麦(Triticum aestivum L., 2n=6x=42)、硬粒小麦(T. durum d. sf., 2n=4x=28)以及栽培二粒小麦(T. dicoccum Schrank 2n=4x=28)之间的属间杂种,平均杂交结实率分别为3.0％、1.2％和0.8％。杂种在形态上偏向小麦,自交不孕,用父本作回交亲本获得了大麦×普通小麦杂种的回交一代。所有杂种均表现细胞学上的不稳定性。杂种减数分裂中期1 PMC染色体平均配对频率和交叉结频率分别为27.31Ⅰ 0.33Ⅱ 0.011Ⅲ,0.45;20.571 0.20Ⅱ 0.008Ⅲ,0.25和20.41Ⅰ 0.28Ⅱ 0.005Ⅲ,0.32,表明双亲染色体组间不存在同源关系。大麦×四倍体小麦杂种小孢子的染色体计数表明,杂种中未减数雄配子的频率在60％以上。     

Iris japonica×Iris confusa种间杂种的细胞遗传学研究

对Irisjaponica、I confusa和它们的人工种间杂种花粉母细胞减数分裂中期Ⅰ染色体配对行为、形态学和繁育特征进行了分析 ,结果表明 :(1)I japonica和I confusa的形态差异较小 ,杂种F1形态介于亲本之间 ;(2 )人工杂交比较容易 ,杂种种子能正常发育 ;杂种F1体细胞染色体数为 2n =30 ,减数分裂中期I染色体配对频率很高 ,为 13 9个二价体 ,构型为0 95Ⅰ + 5 95Ⅱ (棒形 ) + 7 95Ⅱ (环形 ) + 0 0 5Ⅲ + 0 2 7Ⅳ ,表明它们有相似的染色体组 ,亲缘关系很近 ;(3)杂种中有少量的三价体和四价体存在 ,可能是亲本染色体间发生了结构重排或是部分同源染色体配对 ;(4)杂种中大多数细胞存在 2个单价体 ,有的高达 8个单价体 ;花粉育性为 5 0 5 1% ,不能正常结实 ,表明I japonica和I confusa间存在生殖隔离 ,是独立的生物学物种 ;(5 )杂种F1减数分裂前期可观察到细胞融合 ,这可能是造成I japonica和I confusa不同居群出现多倍体和非整倍体的重要原因。     

节节麦×硬粒小麦-簇毛麦双二倍体杂种F_1可孕配子形成途径的细胞学分析

对节节麦×硬粒小麦-簇毛麦双二倍体杂种F_1减数分裂的观察结果表明:该杂种F_1的可孕性是由于杂种F_1产生了大量的(近于)未减数配子的结果。在一些PMC中,单价体中期Ⅰ集结到赤道板上,后期Ⅰ染色单体均等分离产生二分体,二分体发育成有功能的花粉粒。由于染色(单)体的丢失或不分离可产生大量的不完整的重复、缺失未减数配子,完整未减数配子的频率很低。杂种F_1和普通小麦杂交一代及F_2代的细胞学分析结果和F_1配子形成途径分析结果一致。推测从大量的F_2代中可能筛选到自发八倍体(DDAABBVV)。     

种间杂种染色体配对所揭示的披碱草属植物StY基因组分化及其进化意义

在同倍体(homoploid)植物杂交-分化的物种形成(speciation)过程中,杂交后代与亲本之间的有效生殖隔离是新物种形成的关键。杂种与亲本在时间、空间、生态环境和基因水平上的隔离,保证了杂种后代的分化和稳定,并逐渐形成新物种。为了研究披碱草属(Elymus)含StY基因组四倍体物种的系统演化关系,本文对来自亚洲不同地理分布区的26种披碱草属植物进行了大规模的种间杂交和杂种F1减数分裂染色体配对行为的分析。结果表明各物种之间有不同程度的杂交亲合力,杂交结实率在各杂交组合之间有较大的变异(在4．8％-100％之间);但各物种之间的杂种F1完全不育。证明各物种之间形成了明显的生殖隔离。种间杂种F1减数分裂中期-I染色体配对分析的结果进一步表明,StY基因组随各披碱草属物种地理分布的不同而有不同程度的分化。来自同一分布区(如东亚或西亚分布区之内)物种的StY基因组分化程度较低,但来自不同分布区(如东亚和西亚)物种之间相同的StY基因组具有显著的分化。表明地理隔离对含StY基因组物种的分化起到了十分重要的作用。通过对种间和种内杂种F1的减数分裂异常现象和染色体配对频率变化规律的分析,作者认为细胞学水平的变化,如基因组同源性的分化和染色体结构的变异等都在杂种后代与亲本之间产生生殖隔离并逐渐形成新物种的进化过程中起到了积极的作用。     

普通小麦与簇毛麦属间杂种体细胞无性系的建立及双倍体的合成

通过将常规有性杂交,杂种幼胚愈伤组织培养,杂种试管苗无性繁殖,和杂种愈伤组织及试管苗的染色体加倍等环节相结合,由普通小麦x簇毛麦的极少数杂种幼胚在半年时间内获得了上万株杂种植株,并从中产生了数以千计的双倍体种子。经人工接种鉴定,这个双倍体对白粉病免疫,已被用做小麦抗白粉病育种的中间材料。与此同时,在实验室内还保存着相当数量的杂种愈伤组织和试管苗。前者已经过30余次继代,保存了近2年半的时间,仍具有良好的生长和分化能力;后者也已经历了20几次继代,保存了2年,仍可不断增殖。     

Morphology,fertility and cytogenetics of intergeneric hybrid between Roegneria kamoji Ohwi and Dasypyrum villosum (L.) Candargy (Poaceae: Triticeae)

The intergeneric hybrids between Roegneria kamoji Ohwi and Dasypyrum villosum (L.)Candargy were successfully obtained by means of embryo culture in vitro. Studies on morphology, fertility and chromosome pairing behavior in meiosis of the parents and their hybrid F_l were carried out in the present work. The results showed that: (1) there were ob vious morphological differences between R. kamoji and D. villosum, and spikes of F_l plants were morphologically intermediate between the two parental species; (2) the seed set of the cross was 11.63%; the hybrid plant was infertile, which indicated that strong repro ductive isolation existed between the parents and R. kamoji and D. villosum were inde pendent biological species; (3) The somatic chromosome number in root-tips of F_l hybrids was 28. Chromosome pairing at MI of PMCs in F_l hybrids was quite low. The meiotic con figuration was 26.72 Ⅰ + 0.62 Ⅱ + 0.02 Ⅲ, which indicated that very low homoeology was detected between the St, H, Y genomes of R. kamoji and the V genome of D. villo- sum, and the relationship between the parental species was remote.     

簇毛麦的利用价值和染色体操作

簇毛麦是小麦的一个野生近缘种,蛋白质和赖氨酸含量高,抗逆性和抗病性强,特别是对小麦白粉病的绝大多数生理小种表现免疫或高抗,是小麦品种改良中的一种潜在的抗性基因源。本文详细介绍了簇毛麦研究的历史和现状、簇毛麦染色体形态学、生化标记、分子细胞遗传学、分子标记等识别技术,以及簇毛麦与小麦组其它染色体组的关系     

鹅观草与大麦属间杂种的形态和细胞遗传学研究

用活体/离体幼胚培养法成功地获得了鹅观草(Roegneria kamooji,2n=12,SSHHYY)与大麦(Hordeum vulgare,2n=14,11)间的属间杂种。杂交结实率为31.4％,胚培成苗率60.9％。杂种表现一年生,具有很强的生活力,形态上偏向鹅观草。F_1自交不孕,用大麦回交亦不结实。杂种具有预期的2n=28(SHYI)条染色体,花粉母细胞减数分裂中期Ⅰ平均形成26.38个单价体,0.67个棒状二价体,0.12个环状二价体和0.02个三价体。本文对双亲染色体组间的同源性以及在大麦育种中利用鹅观草种质的可能性进行了讨论。     

簇毛麦NBS类R基因相关序列的分子标记开发及其染色体定位

小麦近缘种簇毛麦携带许多尚未克隆的抗病(R)基因。NBS-LRR类型的R基因占已克隆植物R基因的绝大多数,因此,本研究根据NBS-LRR类型R基因的保守序列设计引物,从簇毛麦基因组DNA和cDNA中扩增获得23条相关序列。基于其中5条抗病基因同源序列(RGAs)H-56/d6、H-66/b2和CDS40设计引物,对小麦、簇毛麦、硬-簇双二倍体及其杂种以及已知携带个别簇毛麦染色体或染色体臂的小麦材料进一步进行PCR扩增,结果表明:3对引物均可对簇毛麦、硬-簇双二倍体进行特异扩增;同时,源于序列H-66/b2的引物可对1VL和6VL染色体臂进行特异扩增;源于序列CDS40的引物可在同时携带1VL和2VS或同时携带2VS和4V的小麦材料以及具有6VL的小麦材料中特异扩增,而H-56/d6的引物在携带1VL、2VS、4V和6V染色体臂或染色体的小麦背景中都不能获得目的片段的扩增。这些结果不仅为外源染色体臂在小麦背景中的追踪与鉴定提供了新的分子标记,而且这些标记还与外源染色体或染色体臂上的抗病基因或抗病基因同源物紧密连锁或共分离。     

白菜型油菜(B. Chinensis)与海甘蓝(Crambe abyssinica)属间杂种的细胞学观察

白菜型油菜与海甘蓝属间杂种F₁代染色体数目早期为2n=55。经多代组培无性繁殖后,杂种染色体大量减少,数目变化于25～28条间,平均为26条。杂种PMC减数分裂中,平均配对构型为0.06Ⅲ+11.26Ⅱ+3.80Ⅰ,二价体数目变化于8～13之间,以10Ⅱ、11Ⅱ、12Ⅱ的细胞出现频率较高,分别为26.60%,23.91%和30.98%,单价体数目变化于0～8个之间。杂种染色体数目减少,二价体个数较高,这说明海甘蓝染色体在大量丢失的同时,白菜型油菜的染色体组发生了自然加倍。在后期Ⅱ观察到三分体、染色体落后、染色体桥等异常现象。      

Genome size variations within Dasypyrum villosum: correlations with chromosomal traits, environmental factors and plant phenotypic characteristics and behaviour in reproduction

 Feulgen/DNA cytophotometric determinations carried out in the root meristem of seedlings showed that substantial quantitative alterations in the nuclear genome are present between and within 15 natural populations of Dasypyrum villosum in Italy. When the most variant values are considered, there is a 17.6% difference between the mean genome size of the populations, and a 66.2% difference between the genome size of individual plants within a population. A highly significant, positive correlation was found to exist between the genome size of D. villosum plants and the altitude of their stations, and differences in DNA contents between individual plants were greater in populations from mountain sites. Karyological analyses showed all chromosome pairs to differ largely in size between plants with differing DNA contents. A highly significant, positive correlation was found to exist between genome size and both the length of the chromosome complement at metaphase and the length and arm ratio of pair VII. Significant correlations were also found between DNA content and certain phenotypic characteristics of the plants. The mean genome size of the populations was negatively correlated with the mean leaf length and width. In contrast, the genome size of individual plants was positively correlated with the weight of the seed from which they originated and their flowering interval. A large range of genome sizes was found in the half-sib progeny of a plant having a relatively large genome. In contrast, in the half-sib progeny of a plant having a small genome, the genome sizes of the individual plants were less divergent and similar to that of the mother plant. All siblings from crosses between plants with differing genome sizes had similar DNA contents, which were intermediate between those of the parental plants, even if closer to the DNA content of the parent plant having the smaller genome size. Size polymorphism within pairs was never observed in plants obtained from these crosses or in half-sibs whose genome size differed from that of the mother plant. The intraspecific alterations observed in the nuclear genome and their effects on plant development and phenotype are briefly discussed as evolutionary factors which allow D. villosum populations to withstand different environmental conditions as well as the variability of conditions in a given environment. Received: 6 October 1997 / Accepted: 28 October 1997     

Production of aneuhaploid and euhaploid sporocytes by meiotic restitution in fertile hybrids between durum wheat Langdon chromosome substitution lines and Aegilops tauschii

Fertile F1 hybrids were obtained between durum wheat (Triticum durum Desf.) Langdon (LDN) and its 10 disomic substitution (LDN DS) lines with Aegilops tauschii accession AS60 without embryo rescue. Selfed seedset rates for hybrids of LDN with AS60 were 36.87% and 49,45% in 2005 and 2006, respectively. Similar or higher selfed seedset rates were observed in the hybrids of ID (1A), 1D (1B), 3D (3A), 4D (4B), 7D (TA), and 2D (2B) with AS60, while lower in hybrids of 3D (3B) + 3BL, 5D (5A) + 5AL, 5D (5B) + 5B and 6D (6B) + 6BS with AS60 compared with the hybrids of LDN with AS60. Observation of male gametogenesis showed that meiotic restitution, both first-division restitution (FDR) and single-division meiosis (SDM) resulted in the formation of functional unreduced gametes, which in turn produced seeds. Both euhaploid and aneuhaploid gametes were produced in Fi hybrids. This suggested a strategy to simultaneously transfer and locate major genes from the ancestral species T. turgidum or Ae. tauschii. Moreover, there was no significant difference in the aneuhaploid rates between the F1 hybrids of LDN and LDN DS lines with AS60, suggesting that meiotic pairing between the two D chromosomes in the hybrids of LDN DS lines with AS60 did not promote the formation of aneuhaploid gametes.