远缘杂交不需幼胚培养的节节麦基因型

六倍体普通小麦(Triticum aestivum L.)是由四倍体小麦(T.turgidum L.)与二倍体节节麦(Aegilops tanschii Coss.)天然杂交然后通过染色体自然加倍形成的异源多倍体.这一起源过程是自然条件下天然发生的,它的发生需要具备一个条件:四倍体小麦与节节麦的天然杂交种子在自然条件(没有幼胚培养等)下能够正常发芽出苗.我们从22份节节麦中发现来自中东的节节麦AS60在不采用幼胚培养等人工辅助条件下,仍然很容易与四倍体小麦和普通小麦产生有生活力的杂种植株.AS60与四倍体小麦的杂交种子有50.0%(反交)及57.1%(正交)的种子,而AS60与六倍体普通小麦的杂交种子则有45.5%不需幼胚培养等措施能够正常发芽、生长.AS60的这一特征正是普通小麦起源过程需要的条件.最后探讨了这一发现对小麦遗传改良和对普通小麦起源演化研究的意义.     

小麦幼胚组织培养力的遗传研究

在整个小麦幼胚培养周期内;愈伤组织的诱导、生长、根芽原基的形成和幼苗再生等各个阶段都受遗传机制所控制。多数研究表明;小麦幼胚培养力是受少数主基因控制的“质量性状”;同时也存在一些修饰基因;并且许多控制幼胚培养力的基因位于染色体B上;而且第2,4,6部分同源染色体群对幼胚培养力的影响较大。小麦幼胚培养力也与细胞质因子有关;特定的核质组合与培养条件的互作对幼胚培养力有密切的关系。多数研究者注意到;小麦幼胚培养力可能与小麦Rht和D3等矮源基因(dwarfinggene）有关;并认为这类基因可能通过植物激素代谢及渗透势变化等调控小麦幼胚培养力。     

烯效唑在小麦幼胚培养中的应用

试验结果表明低浓度烯效唑有促进远缘杂交幼胚再生植株生长的作用,高浓度儿唑有抑制作用。附加２．５ｍｇ／Ｌ烯效唑和２％蔗糖的１／２ＭＳ培养基壮苗效果显著,当烯效唑浓度提高到５．０ｍｇ／Ｌ时,植株变矮,但根系发达,结合低温保存,可使幼胚再生植株顺利越夏,移栽时成活率达９６．９％。不同基因型的幼胚再生植株对烯效唑反应无明显差异。     

小麦幼胚培养再生单性雌花的研究

通过45个基因型的小麦（Triticum aestivumL.)幼胚培养,发现有11.1%的基因型从靠近再生芽基部的愈伤组织上分化形成花器官,再生花芽呈裸露的,多子房丛生的,具有藏盛羽毛状柱头而缺乏雄蕊,外稃,内稃和颖片的单性雄花。组织切片观察发现,其雌蕊起源于再生芽附近的分生组织细胞,并通过次生雌蕊再生的方式形成从生状,其羽毛状结构的发育先于子房中胚珠的分化,除正常的单胚珠外,还发现双生胚珠分化。X^2独立性检验结果显示,花芽再生率存在强烈的基因型效应,小麦品种YA-1表现突出（44.4%)。其花芽再生潜力能在不同年份间较好地再现,说明YA-1的花芽再生能力具有相对稳定性,与脱分化培养基的效应相比,YA-1的花芽再生效率主要受继代培养基成分的影响,其中,6-BA,NAA和加倍无机铁盐的配比较2,4,-D和正常浓度无机铁盐的配比更有利于YA-1的幼胚培养再生花芽,同时,外植体实验表明,YA-1的幼穗和成熟胚培养无任何成花反应,而其幼胚外植体具有特异的花芽再生能力。据此认为,YA-1的幼胚培养有助于为小麦花发育机理研究建立理想的实验系统。     

节节麦远缘杂种胚的组织培养(简报)

利用活体-离体胚培养和胚愈伤组织诱导、再生植株技术有效地克服了节节麦远缘杂种胚的败育,高效产生了节节麦与硬粒小麦-簇毛麦双倍体、六倍体小黑麦、小麦、大麦间的杂种植株,从而为节节麦种质利用提供了技术方法。     

向日葵的幼胚培养

实验所用的基本培基中以B_5培养基对向日葵幼胚培养为最适。激素萘乙酸主要促进幼胚的胚性生长。吲哚乙酸(IAA)与激动素(KT)的配合使用,对幼胚的分化起明显的调节作用。天然提取物则明显地促进幼胚生长、其中荸荠汁的培养基可使向日葵球形胚进行正常发育。 用两种改良的B_5培养基做胚胎培养系统,使向日葵种间杂交胚生长发育。先将杂交后的心形胚培养在胚胎生长培养基上,进行充分的胚性生长。然后把胚转移到萌发培养基,使其萌发形成幼苗,最后移入土壤直至开花。     

小麦幼胚培养再生植株第二代若干性状的变异*

再生植株第二代（R₂）各性状如F₂代一样均表现为介于双亲的连续变异;并有超亲遗传。各性状的变异幅度均大于F₂代;超出F₂变异范围的株率依性而有所不同;从1.64——65.3%。R₂代各性状的遗传力较F₂有较大的提高。这些都反映了经体细胞培养后诱导了变异;丰富了R₂的遗传基础。     

小麦幼胚培养再生单性雌花的研究

通过45个基因型的小麦(Triticum aestivum L.)幼胚培养,发现有11.1%的基因型从靠近再生芽基部的愈伤组织上分化形成花器官.再生花芽呈裸露的、多子房丛生的、具有茂盛羽毛状柱头而缺乏雄蕊、外稃、内稃和颖片的单性雌花. 组织切片观察发现,其雌蕊起源于再生芽附近的分生组织细胞,并通过次生雌蕊再生的方式形成丛生状,其羽毛状结构的发育先于子房中胚珠的分化. 除正常的单胚珠外,还发现双生胚珠分化.χ2独立性检验结果显示,花芽再生率存在强烈的基因型效应.小麦品种YA-1 表现突出(44.4%),其花芽再生潜力能在不同年份间较好地再现,说明YA-1的花芽再生能力具有相对稳定性.与脱分化培养基的效应相比,YA-1的花芽再生效率主要受继代培养基成分的影响. 其中,6-BA、NAA和加倍无机铁盐的配比较2,4-D和正常浓度无机铁盐的配比更有利于YA-1的幼胚培养再生花芽.同时,外植体实验表明,YA-1的幼穗和成熟胚培养无任何成花反应,而其幼胚外植体具有特异的花芽再生能力.据此认为,YA-1的幼胚培养有助于为小麦花发育机理研究建立理想的实验系统.     

胚龄和激素对小麦幼胚组织培养的影响

以扬麦158为试验材料,通过田间取样室内培养的方法研究了胚龄和激素对小麦幼胚组织培养的作用。结果表明,幼胚组织培养最适宜的胚龄为14—16d;适宜的2,4-D浓度为1．5-2．5mg/L;适宜的IAA浓度为2．0-3．0mg/L;适宜的6-BA浓度为0．1-0．8mg/L;适宜的KT浓度为0．5—1．5mg/L。因此,胚龄和激素对于小麦幼胚组织培养具有明显的调节作用．在组织培养实践中,充分认识和综合协调这些因素对小麦幼胚组织培养的作用,可以提高组织培养效率,使其更加有利于生物学研究、遗传转化和快速育种等工作。     

基因枪转化小麦幼胚的再生培养与转基因植株的获得

以小麦幼胚为受体,用基因枪法对Trx-S反义基因 目的基因 和Bar基因 标记基因 进行了共转化,以轰击后的小麦幼胚为实验材料,对幼胚培养的基本培养基、分化和生根培养基进行了筛选优化.结果表明:4种基本培养基中,L3培养基的成愈率最高,且增殖速度快;MS培养基次之.以L3为基本培养基,分化培养基中添加NAA1mg·L-1和ZT2mg·L-1配比对愈伤组织诱导分化的效果最好,分化率达到50%以上.1/2MS培养基中添加IAA0.8mg·L-1的生根效果好,且移栽成活率高.以优化的培养方案对来自7个小麦品种的幼胚进行转化与再生培养,多数品种的出愈率都达到90%以上,分化率在40%以上,并在5个品种上获得再生植株,经检测证实在4个品种上获得转基因再生植株.     

基因型和胚龄对小麦未成熟胚离体培养反应的影响

本文对34种基因型的小麦未成熟胚在离体培养中的反应进行了比较。结果表明,94％的供试基因型愈伤组织诱导率都可达到80％以上,若排除供体植株环境条件的不同和接种过程中的人为因素可能造成的影响,不同基因型的愈伤组织诱导率看来没有根本的差异。愈伤组织分化率因基因型的不同变动在0—60％之间,平均为32.7％。虽然同一基因型的盾片愈伤组织分化率在不同年份中有所不同,但是愈伤组织是否具有再生能力?看来是个稳定的遗传性状。因此小麦未成熟胚对愈伤组织诱导的反应和愈伤组织的再生能力可能具有不同的遗传基础。本文的结果还表明,虽然最适于培养的未成熟胚的大小为1毫米左右,伹小至0.3毫米的未成熱胚仍能以几乎100％的频率形成愈伤组织,60％左右的愈伤组织能分化出再生檀株,只是所需的时间比1毫米左右的胚较长。     

节节麦细胞不同分裂时期和阶段的G—带核型及其变动性分析

采用改良的ASG法获得了中期和3个染色体凝缩程度不同的早中期阶段（分别称为早中期Ⅰ、Ⅱ、Ⅲ）染色体的G-带,并进行了G-带核型和变动性分析。所分析的分裂时期和阶段,每条染色体的全长显示出了密切邻近的多重的带纹,带纹细窄、大小较相近,带间区小,带纹分布较密集而均匀。随着有丝分裂进程推进,染色体的带纹数目减少,早中期Ⅰ、Ⅱ、Ⅲ于中期单倍染色体组的G-带带纹总数分别减少41%、36%、28%,而染色体组的绝对长度分别缩短43%、37%、27%,带数减少幅度与染色体长度缩短的幅度几乎相等。早中期Ⅰ至早中期Ⅱ、Ⅲ和早中期Ⅱ至早中期Ⅲ的带纹减少幅度与染色体长度缩短幅度也基本一致。染色体组中各染色体之间带纹减少和染色体缩短的比例不尽相同,有一定的变幅。早中期Ⅰ、Ⅱ、Ⅲ和中期染色体组中每单位绝对长度的带数（带/μm）分别为2.19、2.22、2.32和2.29,差异不大。对节节麦G-带的特性等问题进行了讨论。     

小麦幼胚培养高效成株系统的建立

研究探讨了不同的基因型、幼胚取材时期、4℃处理时间、盾片接种方式、分化及生根条件等对小麦幼胚培养再生成株特性的影响,并在此基础上建立了一套高效、可靠、重复性好的小麦组培再生系统。优化条件下,该系统从幼胚诱导致密愈伤组织的频率为89％,致密愈伤组织的分化频率诱导2周时为95％,培养近3个月时仍可达50％以上。此外还发现部分叶状结构当转至新鲜的分化培养基上时能够进一步发育成为芽苗。分化的芽苗在生根培养基上大多生成丛生苗。从基部切开后,每棵芽苗／分蘖均可独立成株。组培苗均可正常地开花结实。     

A high-density genetic linkage map of Aegilops tauschii, the D-genome progenitor of bread wheat

 Aegilops tauschii is the diploid D-genome progenitor of bread wheat (Triticum aestivum L. em Thell, 2n=6x=42, AABBDD). A genetic linkage map of the Ae. tauschii genome was constructed, composed of 546 loci. One hundred and thirty two loci (24%) gave distorted segregation ratios. Sixty nine probes (13%) detected multiple copies in the genome. One hundred and twenty three of the 157 markers shared between the Ae. tauschii genetic and T. aestivum physical maps were colinear. The discrepancy in the order of five markers on the Ae. tauschii 3DS genetic map versus the T. aestivum 3D physical map indicated a possible inversion. Further work is needed to verify the discrepancies in the order of markers on the 4D, 5D and 7D Ae. tauschii genetic maps versus the physical and genetic maps of T. aestivum. Using common markers, 164 agronomically important genes were assigned to specific regions on Ae. tauschii linkage, and T. aestivum physical, maps. This information may be useful for map-based cloning and marker-assisted plant breeding. Received: 23 March 1998 / Accepted: 27 October 1998     

Retroelement insertional polymorphisms, diversity and phylogeography within diploid, D-genome Aegilops tauschii (Triticeae, Poaceae) sub-taxa in Iran

Background and Aims: The diploid goat grass Aegilops tauschii (2n = 2x = 14) is nativeto the Middle East and is the D-genome donor to hexaploid breadwheat. The aim of this study was to measure the diversity ofdifferent subspecies and varieties of wild Ae. tauschii collectedacross the major areas where it grows in Iran and to examinepatterns of diversity related to the taxa and geography. Methods: Inter-retroelement amplified polymorphism (IRAP) markers wereused to analyse the biodiversity of DNA from 57 accessions ofAe. tauschii from northern and central Iran, and two hexaploidwheats. Key Results: Eight IRAP primer combinations amplified a total of 171 distinctDNA fragments between 180 and 3200 bp long from the accessions,of which 169 were polymorphic. On average, about eight fragmentswere amplified with each primer combination, with more bandsbeing amplified from accessions from the north-west of the countrythan from other accessions. Conclusions: The IRAP markers showed high levels of genetic diversity. Analysisof all accessions together did not allow the allocation of individualsto taxa based on morphology, but showed a tendency to put accessionsfrom the north-west apart from others regions. It is speculatedthat this could be due to different activity of retroelementsin the different regions. Within the two taxa with most accessions,there was a range of IRAP genotypes that could be correlatedclosely with geographical origin. This supports suggestionsthat the centre of origin of the species is towards the south-eastof the Caspian Sea. IRAP is an appropriate marker system toevaluate genetic diversity and evolutionary relationships withinthe taxa, but it is too variable to define the taxa themselves,where more slowly evolving morphological, DNA sequence or chromosomalmakers may be more appropriate.     

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.     

幼胚培养创造抗白粉病簇毛麦6VS端体

通过白粉病抗性鉴定、生化标记及分子原位杂交相结合的方法,从小麦(Triticum aestivum L.)幼胚培养组合T240 (普通小麦×小麦-簇毛麦(Haynaldia villosa Lam.) 6D/6V异代换系)的32个SC2代株系中,筛选出T240-6株系,其所有的抗白粉病单株均缺失簇毛麦6V染色体长臂上的谷草转氨酶位点GOT-V2,而具有短臂上的醇溶蛋白位点Gli-V2.细胞学染色体观察表明,该株系的所有抗病单株均具有1～2个端体,这些端体不能与小麦染色体配对,双端体之间可以配对.经原位杂交分析,端体杂交呈阳性,表明它们均为簇毛麦6V染色体短臂(6VS).     

Characterisation of high- and low-molecular weight glutenin subunits associated to the D genome of Aegilops tauschii in a collection of synthetic hexaploid wheats

Synthetic hexaploid wheats (2n=6x=42, AABBDD) involving genomes from Triticum turgidum (2n= 4x=28, AABB) and Aegilops tauschii (2n=2x=14, DD) have been produced as a means for introducing desirable characteristics into bread wheat. In the present work we describe the genetic variability present at the Glu-D ^t 1 and Glu-D ^t 3 loci, encoding high- (HMW) and low-molecular-weight (LMW) glutenin subunits respectively, derived from Ae. tauschii, using electrophoretic and chromatographic methods, in a collection of synthetic hexaploid wheats. A wide variation both in mobility and surface hydrophobicity of HMW glutenin subunits was observed between different accessions of Ae. tauschii used in the production of the synthetic hexaploids. A combination of electrophoretic and chromatographic methods improves the identification of HMW glutenin subunits; in fact subunits with identical apparent mobility were revealed to have a different surface hydrophobicity by reversed-phase high performance liquid chromatography. None of the Dx5^t subunits present in Ae. tauschii showed the presence of the extra cysteine residue found in the HMW glutenin subunit Dx5 of Triticum aestivum, as revealed by selective amplification with polymerase chain reaction (PCR). The wide variability and the high number of subunits encoded by the Glu-D ^t 3 locus suggests that Ae. tauschii may be a rich source for enhancing the genetic variability of glutenin subunits in bread wheat and improving bread-making properties. Received: 3 March 2001 / Accepted: 23 March 2001