外源细胞质诱导小麦单倍体的机理与应用研究——Ⅱ.Ptg基因的表达及其在小麦单倍体育种上利用途径的初步研究

本文通过对具粘果山羊草细胞质的小黑麦(AABBDDR和AABBDDRR)和1R小麦-黑麦附加系的研究,证明1BS对Ptg基因表达无抑制作用,并据此提出了一种利用染色体工程手段创造既自花结实又能诱导单倍体的异质品系的方案,为利用外源细胞质获得的大量单倍体进行小麦的单倍体育种提供了理论依据。对几个具普通小麦细胞质的1B/1R易位系的研究证明,Ptg基因在普通小麦细胞质背景下也可以表达,但外显率很低。     

The Inheritance of Resistance to Septoria Glume Blotch II. The Wild Wheat Species Aegilops speltoides

The inheritance of resistance in the wild wheat species Ae. speltoides L. to Septoria glume blotch (Septoria nodorum Berk.) was investigated. It was characterized by two parameters measured on detached leaves, namely lesion size (LS) and length of latent period (LP), and by the severity of the disease under field conditions (DS). The genetic analysis was based on the F₁ and F₂ generations of a 4 × 4 diallel cross between four Ae. speltoides accessions showing differential resistance to the pathogen. The three parameters of resistance were highly correlated. Considerable heterosis for resistance was found for each of the parameters in most of the diallel combinations. The estimates of broad-sense heritability were moderately high (0.50 — LS, 0.60 — LP, 0.52 — DS), while the estimates of narrow-sense heritability were low (0.16 for LS, 0.20 for LP, 0.25 for DS). There were no indications for genie interaction. It is suggested that the resistance is controlled by at least two genes with over-dominance of the alleles for higher resistance. Highly resistant Ae. speltoides accessions are a potential source of germplasm for improving the resistance of cultivated wheats to Septoria glume blotch. The possibility of using dominant alleles for resistance in hybrid cultivars is discussed.     

The study of introgressive lines of Triticum aestivum × Aegilops speltoides by in situ and SSR analyses

Fluorescence in situ hybridization (FISH) with a genome‐specific repeat, Spelt1, and wheat simple sequence repeat (SSR) markers were used to analyse the chromosome constitution of two Triticum aestivum×Aegilops speltoides introgressive lines. The lines 170/98i and 178/98i carried one and two subtelomeric regions of Ae. speltoides (per haploid genome), respectively, marked by Spelt1 repeats according to FISH data. SSR analysis detected homoeologous substitution of wheat chromosome 7D with Ae. speltoides chromosome 7S in the lines 178/98i and 170/98i as well as the assumed terminal translocation in the short arm of chromosome 3A in the line 178/98i. Anthocyanin pigmentation of the coleoptiles was found in the lines 170/98i and 178/98i and resulted from the 7S (7D) substitution. It was demonstrated that Spelt1 could be effectively used for the rapid identification (without DNA isolation) of terminal translocations of T. aestivum×Ae. speltoides introgressive lines as well as for further analysis of the stability of the hybrid plants.     

Comparison of genetic variation among accessions of <Emphasis Type="Italic">Aegilops tauschii</Emphasis> using AFLP and SSR markers

Genetic diversity of 54 accessions of Aegilops tauschii from five countries was assessed using sequence-tagged microsatellites (or simple sequence repeats, SSRs) and amplified fragment length polymorphisms (AFLPs). In the case of AFLP analysis, a total of 256 amplification products obtained, 234 of them were polymorphic across all the 54 accessions. A total of 224 fragments were obtained from the 24 SSR primers and 219 of fragments were polymorphic across all the genotypes screened. Based on both AFLP and SSR markers, the highest percentage of polymorphisms were obtained in Iranian and accessions of unknown origin. The highest polymorphic information content (PIC) value was observed for SSRs (0.82) while the highest marker index (MI) value was for AFLPs (8.5) reflecting the hyper-variability of the first and the distinctive nature of the second system. Principal co-ordinate analysis (PCO) revealed congruent patterns of genetic relationships for both data sets, but did not group accessions strictly according to their geographical origins. Poor correlation was found between AFLP and SSR marker loci. This low association may be due to low number of AFLP and SSR markers. These results show that molecular markers can help to organize the genetic variability and expose useful diversity for breeding purposes.     

Applicability of Aegilops tauschii drought tolerance traits to breeding of hexaploid wheat

Few genes are available to develop drought-tolerant bread wheat (Triticum aestivum L.) cultivars. One way to enhance bread wheat’s genetic diversity would be to take advantage of the diversity of wild species by creating synthetic hexaploid wheat (SW) with the genomic constitution of bread wheat. In this study, we compared the expression of traits encoded at different ploidy levels and evaluated the applicability of Aegilops tauschii drought-related traits using 33 Ae. tauschii accessions along with their corresponding SW lines under well-watered and drought conditions. We found wide variation in Ae. tauschii, and even wider variation in the SW lines. Some SW lines were more drought-tolerant than the standard cultivar Cham 6. Aegilops tauschii from some regions gave better performing SW lines. The traits of Ae. tauschii were not significantly correlated with their corresponding SW lines, indicating that the traits expressed in wild diploid relatives of wheat may not predict the traits that will be expressed in SW lines derived from them. We suggest that, regardless of the adaptability and performance of the Ae. tauschii under drought, production of SW could probably result in genotypes with enhanced trait expression due to gene interactions, and that the traits of the synthetic should be evaluated in hexaploid level.     

利用小麦A、B基因组特异SSR标记扩增节节麦D基因组

以节节麦SQ-214、中国春(CS)和四川育成品种SW3243为材料,利用192个小麦A和B基因组特异SSR标记,对节节麦D基因组进行了扩增,结果表明:有130个特异SSR标记(67.70%)可以在只含D基因组的节节麦上扩出产物,并对扩增效果进行了分析。     

CYTOGENETIC INVESTIGATION OF THE HYBRID BETWEEN AEGILOPS TAUSCHH AMD PSATHYROSTACHYS HUASHANICA

<正> An intergeneric hybrid between Aegilops tauschti Cosson. an annual diploid grass. and Psathyrostachys huashanica Keng, a perenmal diploid grass. The F_1 hybrid plant had chromosome number of 2n=2x=14. and was annual and morphologically intermediate between two parents. Meiotic analysis showed that this F_1 hybrid had an average of 12.20 univalants, 0.12 rod bivalents ad 0.004 quadrivalents at MI of the pollen-mother-cells. Multipolar division, irregular ctyokinesis. conjungation opening and coenocyte were observed in this hybrid. These results suggested that the D genome in the Ae. tauschii was distantly related to the N genome in the P huashanica.     

利用SSR标记分析19份山羊草属种D基因组遗传多样性

具有D染色体组的山羊草属种是六倍体普通小麦的二级基因源,蕴藏着丰富的抗性基因和遗传变异丰富,可供现代小麦改良利用。选用24对D染色体组特异性微卫星(SSR)标记引物,将19份山羊草属种的D染色体组与3个普通小麦的D染色体组的遗传多样性进行了比较分析。共检测出679个等位基因,每个SSR位点上能检测到1~44个等位基因,平均28.29个。聚类分析结果表明,同一属种的材料基本上聚为一类,19份山羊草属种的D染色体组与普通小麦的D染色体组之间存在较大的遗传差异,可供小麦远缘杂交以丰富栽培小麦遗传多样性。     

一种节节麦高分子量麦谷蛋白与小麦同源蛋白氨基酸序列的比较

对节节麦的一种y类高分子量麦谷蛋白基因进行了序列测定和比较。结果显示,该亚基与小麦A、B和D和节节麦D染色体编码的y型亚基的全蛋白氨基酸残基数目均不一致。6个y型基因的信号肽、N-端和C-端氨基酸残基数目均一致,但有个别氨基酸的替换。而重复区氨基酸残基数目均不一致,主要由于重复单元六肽和九肽的数目不等。在目前已知的D基因组编码的y型亚基中,Dy13t的重复区是最短的,它比Dy10少4个九肽,比Dy12少4个九肽,2个六肽,比Dy12t少4个九肽。由N-Calign序列所作的聚类分析将这6个y型亚基分为3支,A、B和D基因组编码的亚基各占一支。来源于D基因组的4个基因的一支,又可将来源于节节麦和小麦D基因组的2个基因分别聚类在一起。     

普通小麦与山羊草叶绿体基因组长度热点突变区的核苷酸序列分析

 检测了Ae. speltoides和Ae. ovata叶绿体基因组的一个长度热点突变区的核苷酸序列，并与普通小麦、四倍体Ae. crassa 以及Ae. squarrosa的相应序列进行了比较分析。从rbcL基因的终止密码子到cemA基因内的HindIII位点，Ae. speltoides和Ae. ovata的核苷酸序列长度分别为2 808 和 2 810bp。与四倍体Ae. crassa的序列相比，在普通小麦和Ae. speltoides中各有一个791 bp的大片段缺失，在Ae. ovata中存在一个793 bp的大片段缺失。Ae. ovata的缺失片段比普通小麦和Ae. speltoides的长2个碱基，推测Ae. ovata的大片段缺失在进化上是独立发生的。Ae. speltoides的大片段缺失与普通小麦的完全相同，支持Ae. speltoides是普通小麦叶绿体基因组供体的假说。除了大片段缺失外，在这个区域还检测到了7 个插入/缺失和15个碱基替换突变。研究结果表明，这个长度热点突变区的核苷酸序列分析是研究小麦与山羊草叶绿体基因组之间遗传变异关系的一个非常有效的途径。