Genome-specific markers of tetraploid wheats and their putative diploid progenitor species

The objective of this study was to isolate genome‐specific markers from the genomes of tetraploid wheats and the putative donor diploid species on the basis of random amplified polymorphic DNA analysis followed by cross‐hybridization. Twenty different Triticum and Aegilops species and accessions were analysed by polymerase chain reaction (PCR) using 30 random primers. The polymorphic PCR fragments were then isolated, labelled and used in cross‐hybridization screenings. The hybridization results established that one marker was specific to the Ae. speltoides S genome, two to the A genome, one to the B genome and five to the G genomes of polyploid species (and to the genomes of the corresponding progenitor species). Four markers were identified that were specific to both the B and G genomes. Analysis of the Triticum and Aegilops species and accessions supported the notion that Ae. speltoides is more closely related to the B and G genomes of polyploid wheat species than were other members of the Sitopsis section. The data also indicated that the B and G genomes had originated from different accessions of Ae. speltoides.     

Origin of Sv Genome of Aegilops variabilis and Utilization of the Sv as Analyser of the S Genome of the Aegilops Species in the Sitopsis Section

Hybrids of Aegilops variabilis (2n = 28, UUS^vS^v) with the low-pairing type lines of Ae. longissima, Ae. bicornis, Ae. searsii, Ae. speltoides and Ae. umbellulata were obtained. This is the first report of successful hybridization between Ae. variabilis and Ae. searsii. Meiotic analysis of these hybrids showed that the U genome of Ae. variabilis donated by Ae. umbelltilata remained nearly unchanged and Ae. longissima is the possible donor species of the S genome to Ae. variabilis. But the S^v genome and the S¹ genome of Ae. longissima are not completely homologous and are structurally differentiated by at least one interchange. According to their levels of homology with S^v through the means of chromosome associations, the four genomes of Sitopsis section species can be classified as follow: S^v? S¹ > S^b > S^s > S. The meiotic behaviour of the hybrids between the wheat ‘Chinese Spring’ and the four Sitopsis section species studied has not supported the view that one of the four species is the donor of the B genome of wheat.     

四倍体小麦染色体4A和B、G染色体组的起源

用染色体 N—分带技术对四倍体小麦(AABB 和 AAGG)以及 B 和 G 染色体组的可能供体拟斯卑尔脱山羊草(Ae.speltoides)、高大山羊草(Ae.longissima)、沙融山羊草(Ae.sharonensis)、二角山羊草(Ae.bicornis)和西尔斯山羊草 Ae.se-arsii 的体细胞染色体进行核型分析。除染色体4 A 以外的所有 A 组染色体只有较浅的 N—带或无带。B     

普通小麦rDNA的ITS区及其基因组起源

采用特异引物对普通小麦(Triticum aestivum L.) rDNA的ITS区片段进行PCR扩增并测序,通过邻接法聚类分析, 得到3种类型的扩增产物。结果表明,ITS区序列长度是602 bp,其中ITS1和ITS2分别有8个和20个变异位点,ITS区揭示的遗传分化距离变化范围为0~0.038,平均值为0.021。通过从GenBank搜索并下载普通小麦野生近缘种ITS序列与本研究获得的普通小麦ITS序列进行比对,并用MEGA、PAUP、PHYLIP软件分析,按Kimura-2参考模型计算分化距离,以旱雀麦(Bromus tectorum)为外类群邻接法构建聚类树。根据杂交后代具有亲本的ITS序列遗传特点,认为小麦形成较晚,尚未同步进化完全,从分子水平上为普通小麦是异源六倍体提供了证据。通过与其A、B、D基因组可能供体的ITS区序列进行比对分析发现各自有不同程度的变异,认为普通小麦在多倍体形成过程中发生了序列消除现象,结合我们提出的“同步进化”对于不同的基因或者说不同类型的DNA序列是不同步的假说,解释了无法找到真正供体的原因。综上所述,我们认为A、B、D基因组的原初供体可能分别是乌拉尔图小麦(T. urartu)、山羊草(T. speltoides)和节节麦(T. tauschii)。     

Effect of genome and ploidy on photosynthesis of wheat

We assessed (1) the effects of addition and doses of the D genome from different sources and (2) the addition of either the A genome or the D genome on the photosynthesis of synthesized hexaploid wheats. On average, the increased doses of the D genome reduced photosynthesis, but the depression was dependent on the source of the D genome. Two accessions of Aegilops squarrosa had depressed photosynthetic rates, but not another accession of Ae. squarrosa. The D genome of cv. Thatcher did not contribute to depress photosynthetic rate. Triticum monococcum had considerably higher photosynthetic rates than Ae. squarrosa. However, addition of the A genome from T. monococcum did not increase the photosynthetic rates of hexaploids. Chlorophyll a : b ratio, functional photosystem II and the core complex of photosystem II did not account for the variation in photosynthetic rate among the genotypes studied. In our experiment, photosynthesis of polyploids was not dependent on photosynthesis rates of the donor genomes. This revised version was published online in July 2006 with corrections to the Cover Date.     

小麦族的基因组显性及其育种学意义

小麦族包含大量由不同基因组组成的异源多倍体物种。同一个异源多倍体物种的不同基因组可能对表型性状产生非对称性贡献,例如小麦属多倍体物种的形态分类特性,更像其A基因组供体物种,这种现象称为A基因组显性。由于基因组显性,小麦族形成了以A、D、U、St为轴心(显性)基因组的异源多倍体物种簇。异源多倍体物种的基因组显性可能与其进化适应优势的形成有关。在育种方面,基因组显性影响多倍体新作物开发及小麦-外源染色体易位设计。     

不同水肥条件下二倍体、四倍体和六倍体小麦养分吸收、利用效率的研究

试验选用了3个二倍体（Triticum boeoticum，AA；Aegilops speltoides，BB和Ae. tauschii，DD）、2个四倍体（T. dicoccoides，AABB和T. dicoccum，AABB）和1个六倍体（T. aestivum，AABBDD）的小麦进化材料，在不同水肥条件下研究小麦进化中养分效率的差异及水肥条件对小麦养分利用的影响。试验表明，随小麦的进化，养分（N、P和K）吸收量和吸收效率显著增加，但是籽粒养分含量却减少。水分胁迫和低肥处理减少小麦籽粒养分含量、（整株）养分吸收量和吸收效率。小麦的生物量养分利用效率和产量养分利用效率都存在显著的种间差异，而且后者的差异更大。随小麦的进化，生物量养分利用效率和产量养分利用效率均显著增加。6个小麦进化材料的生物量氮、磷利用效率（NUTEb和PUTEb）的大小顺序相同，均为：Ae. speltoides > T. dicoccum、T. dicoccoides、Ae. tauschii、T. boeoticum > T. aestivum，而生物量钾利用效率（KUTEb）是T. aestivum、Ae. tauschii、Ae. speltoides > T. dicoccoides > T. dicoccum > T. boeoticum。Ae. tauschii的产量养分利用效率显著高于其他两个二倍体小麦（AA和BB），表明D组染色体上存在有控制高效利用养分的基因。产量氮、磷、钾利用效率（NUTEg、PUTEg、KUTEg）和收获指数（HI）的大小排序均为：T. aestivum > T. dicoccum、T. dicoccoides、Ae. tauschii > T. boeoticum、Ae. speltoides。水分与养分对生物量养分利用效率有显著影响，而对产量养分利用效率的作用却不显著，说明小麦产量养分利用效率是较为稳定的特性，主要由基因型决定。水分胁迫有利于提高小麦生物量养分利用效率，但是增加施肥量却对其有负作用。     

应用RAPD技术研究不同种山羊草叶绿体DNA的遗传变异

采用随机扩增多态性ＤＮＡ（ＲＡＰＤ）技术研究了山羊草属ｃｐＤＮＡ的遗传变异性。用改良的“高盐低ｐＨ法”提取了１５种山羊草材料和一种二粒小麦的叶绿体ＤＮＡ,并建立了重复性较好的ＲＡＰＤ标准分析条件。在此标准条件下,检测了１６个材料叶绿体ＤＮＡ的多态性。经１０个引物扩增,在得到的６４个片段中,有６个片段是１６个材料共有的,多态性达９０％。聚类分析结果显示,关系较近的有小亚山羊草和欧山羊草,粘果山羊草和     

TaMyb2-Ⅱ基因在普通小麦(Triticum aestivum L.)及其近缘种中的单核苷酸多态性分析

以39份抗旱性不同的普通小麦、5份A基因组材料、4份拟斯卑尔脱山羊草（Aegilops speltoides）、6份粗山羊草（Aegilops tauschii）和2份四倍体小麦,分析TaMyb2基因的核苷酸序列长度多态性和单核苷酸多态性,及其与抗旱性的关系。结果发现,TaMyb2在A基因组材料中无目标片段扩增,在其他材料中检测到Ⅰ、Ⅱ、Ⅲ 3种类型序列。经详细分析,TaMyb2-Ⅱ序列长1 606 bp,在供试材料77 088 bp的核苷酸序列中包括34个单核苷酸变异,其中26个SNP,8个InDel,二者出现的频率分别为1/2 965 bp和1/9 636 bp,编码区π值（0.00055）小于非编码区的π值（0.00185）, 说明编码区的遗传变异小于非编码区的遗传变异。从SNP水平上分析,发现普通小麦与其D基因组供体种粗山羊草及四倍体小麦的亲缘关系较近,与B基因组供体种拟斯卑尔脱山羊草的亲缘关系较远。48份材料的TaMyb2-Ⅱ序列共分为18个单倍型（haplotype）,其中haplotype 2、3、5、6、8、9均为旱地栽培的普通小麦品种,说明普通小麦TaMyb2-Ⅱ的这几个haplotype结构可能与抗旱性有关。     

CIMMYT新型人工合成小麦Pina和Pinb基因等位变异

六倍体人工合成小麦由硬粒小麦（Triticum turgidum subsp. durum）与粗山羊草（Aegilops tauschii Coss.）杂交产生,是研究小麦进化过程中基因变异的重要材料。以国际玉米小麦改良中心（CIMMYT）提供的57份由野生二粒小麦（T. turgidum subsp. dicoccoides）与粗山羊草杂交产生的新型人工合成六倍体小麦为材料，用单籽粒特性测定仪和Pina、Pinb特异性PCR引物对其籽粒硬度变异以及控制籽粒硬度的主效基因Pina和Pinb的分布情况进行了研究。结果表明，这些材料的SKCS硬度值变异较大，从10.5到42.6，其中15~30的占78%。共有Pina-D1a、Pina-D1c、Pinb-D1h和Pinb-D1j 4种等位变异型，基因型为Pina-D1a/Pinb-D1j的8个，占14%；基因型为Pina-D1c/Pinb-D1h的49个，占86%。方差分析表明，基因型Pina-D1a/Pinb-D1j与Pina-D1c/Pinb-D1h对籽粒硬度的影响差异不显著，但父本粗山羊草和母本野生二粒小麦以及二者间的互作对籽粒硬度有显著影响，说明除Pina和Pinb外，还有其他微效基因影响籽粒硬度的形成。     

小麦族物种线粒体基因rrn18-trnfM区域的序列多样性分析

为了研究线粒体基因组在小麦族物种中的遗传变异与进化关系，选用小麦族的14个二倍体及7个多倍体物种，对其线粒体rrn18-trnfM基因区域进行PCR扩增并对扩增所得的片段进行克隆测序。获得大小不同的2种片段类型，大片段为513或515bp，小片段为447或449bp。其主要差异在trnfM区，即大片段存在trnfM基因，小片段缺失trnfM基因，再次证明以前报道的大麦属和小麦属间的分歧。而中间偃麦草同时存在两扩增片段类型，表明多倍体物种mtDNA具有双亲遗传现象。中间偃麦草的RT-PCR分析发现小片段没有转录，大片段能转录，因而考虑高频重组和选择性表达作为中间偃麦草的线粒体基因组独特的进化系统，这与核基因组进化系统不同。     

Variation for apparent amylose content of endosperm starch in Triticum durum and Aegilops squarrosa

For breeding to increase amylose content in the starch of hexaploid wheat, either the introduction of genes from Aegilops squarrosa (DD genome) or the development of high-amylose amphiploids between Triticum durum (AABB genome) and Ae. squarrosa is one of the most efficient ways. The high-amylose genes have not been detected in any species of Triticum and Aegilops. Therefore, we assessed the apparent amylose content in endosperm starch of T. durum and Ae. squarrosa accessions supplied from the major gene banks from world wide, and found several accessions with higher amylose content out of 665 T. durum accessions and out of 732 Ae. squarrosa accessions. Genetic analysis indicated that a high amylose trait in Ae. squarrosa is monogenically inherited by a recessive major gene. This revised version was published online in July 2006 with corrections to the Cover Date.     

Growth dependency of wild,primitive and modern cultivated wheat lines on vesicular-arbuscular mycorrhiza fungi

Summary Mycorrhizal colonization and growth dependency were studied at a single rate of phosphorous application in wild and cultivated primitive and modern wheats, inoculated with Glomus intraradices Schenck & Smith. Mycorrhizal colonization found in Triticum timopheevii var. araraticum (AAGG) was higher than that found in the other tetraploid wheats (AABB). Mycorrhizal dependency was higher in representatives of the D genome donor — Aegilops squarrosa, compared with representatives of the A and possible B genome donors T. monococcum and Ae. sharonensis, Ae. longissima and Ae. speltoides, respectively. The nature of response to VAM in hexaploid wheat was controlled by factors of the A and B genomes which are epistatic over those located in the D genome. The high mycorrhizal colonization and dependency which was found in T. timopheevii var. araraticum may indicate special genomic affinity possessed by the G genome of wheat in VAM interaction. Based on the 27 wheat lines and species tested in this study only low correlation between G. intraradices colonization and its contribution to plant growth can be suggested.     

粗山羊草全基因组Aux/IAA基因家族的分离、染色体定位及序列分析

生长素是植物生长发育过程中的关键激素之一,Aux/IAA家族基因是重要的生长素原初响应基因。通过生物信息学方法从粗山羊草(Aegilops tauschii)全基因组中分离出28个Aux/IAA基因,其中20个粗山羊草Aux/IAA蛋白具有4个保守结构域;28个Aux/IAA基因分布于全部7对染色体上,5个基因分别具有位于同一位点的已知标记。粗山羊草IAA3、IAA11和IAA26的表达具有组织特异性,分别在雌蕊、种子和根中特异表达。系统发育显示,11对粗山羊草-乌拉尔图小麦Aux/IAA蛋白、5对粗山羊草-大麦Aux/IAA蛋白直系同源。共线性分析表明,粗山羊草Aux/IAA基因与短柄草、水稻中同源基因具有很好的共线性。本研究分离的相关基因不仅可用于小麦的遗传改良,也为深入研究小麦Aux/IAA基因提供了信息。     

利用比较基因组学开发山羊草属InDel分子标记

为开发和利用小麦野生近缘种的有益基因, 采用比较基因组学方法, 通过拟斯卑尔脱山羊草EST(expressed sequence tag)与小麦UniGene序列的比对分析, 发现山羊草插入/缺失(InDel)位点137个, 在这些位点两端序列设计引物24对, 通过在15个小麦野生近缘属种基因组DNA的扩增分析, 发现11对引物具多态性, 可以作为InDel标记。这些包含突变位点的基因涉及亚细胞定位、蛋白质结合与催化以及代谢等过程。     

野生二粒小麦（Triticum dicoccoides）与普通小麦（T. aestivum）A、B染色体组的同源性分析

以普通小麦农家种、野生二粒小麦和野生二粒小麦与节节麦合成的双二倍体为材料,运用SSR分子标记方法对野生二粒小麦与普通小麦A、B染色体组的同源性进行了研究。结果表明：（1）野生二粒小麦与普通小麦A、B染色体组的遗传相似系数仅为0.189,存在较大的差异,推测野生二粒小麦与普通小麦的A、B染色体组在长期的进化过程中,     

小麦族物种线粒体基因rrn18–trnfM区域的序列多样性分析

为了研究线粒体基因组在小麦族物种中的遗传变异与进化关系,选用小麦族的14个二倍体及7个多倍体物种,对其线粒体rrn18-trnfM 基因区域进行PCR扩增并对扩增所得的片段进行克隆测序。获得大小不同的2种片段类型,大片段为513或515 bp,小片段为447或449 bp。其主要差异在trnfM区,即大片段存在trnfM基因,小片段缺失trnfM基因,再次证明以前报道的大麦属和小麦属间的分歧。而中间偃麦草同时存在两扩增片段类型,表明多倍体物种mtDNA具有双亲遗传现象。中间偃麦草的RT-PCR分析发现小片段没有转录,大片段能转录,因而考虑高频重组和选择性表达作为中间偃麦草的线粒体基因组独特的进化系统,这与核基因组进化系统不同。     

Characterisation of powdery mildew resistant lines derived from crosses between Triticum aestivum and Aegilops speltoides and Ae. mutica

Characterisation of introgressions of powdery mildew resistance into wheat from Aegilops speltoides and Ae. mutica was attempted by the application of cytological analysis of meiotic behaviour and molecular markers, based on isozymes and RAPD (random amplified polymorphic DNA). Cytological results suggest that a chromosome segment of Ae. speltoides has been successfully translocated to a wheat chromosome, while transfers from Ae. mutica appear to consist of whole chromosome substitutions. RAPD analysis detected eight bands in the line Sp1, and six bands in the line Mt1, which may be potential markers for powdery mildew (PM) resistance. In all Mt progenies the Ep-T1 product segregated, suggesting that the resistance gene is associated with the group 7 homoeologue in Ae. mutica. This revised version was published online in August 2006 with corrections to the Cover Date.     

小麦与山羊草双二倍体抗病性的研究与利用

本文报道了波斯小麦与粗山羊草(5个品系),小伞山羊草和卵穗山羊草双二倍体及其亲本的抗叶锈和白粉病鉴定结果。粗山羊草对叶锈的抗性受波斯小麦品系 PS 5(不抗叶锈)的抑制,在双二倍体中不能表现。小伞山羊草和卵穗山羊草对叶锈的抗性不受波斯小麦的影响,能在双二倍体中充分表达。以对白粉病免疫的波斯小麦为母本与免疫的山羊     

Comparative genetics and disease resistance in wheat

The hexaploid wheat genome is too complex for direct map-basedcloning and model genomes have to be used to isolate genes from wheat.Comparative genomic analysis at the genetic map level has shown extensiveconservation of the gene order between the different grass genomes inmany chromosomal regions. However, little is known about the geneorganization in grass genomes at the microlevel. We have investigated themicrocollinearity at Lrk gene loci in the genomes of four grass species:wheat, barley, maize and rice. The Lrk genes, which encodereceptor-like kinases, were found to be consistently associated with anothertype of receptor-like kinase (Tak) on chromosome groups 1 and 3 inTriticeae and on chromosomes homoeologous to Triticeae group 3 in theother grass genomes. On Triticeae chromosome group 1, Tak and Lrk together with genes putatively encoding NBS/LRR proteins form acluster of genes. Comparison of the gene composition at orthologous Lrk loci in wheat, barley and rice revealed a maximal gene density of onegene per 5 kb. We conclude that small and large grass genomes containregions which are highly enriched in genes. Microrearrangements betweendifferent grass genomes have been found and therefore, the choice of agood model genome is critical. We have recently started to work on theT. monococcum model genome and confirmed its usefulness foranalysis of the Lr10 leaf rust disease resistance locus in wheat.