Location of a gene for frost resistance on chromosome 5A of wheat

Summary A gene for frost resistance on chromosome 5A of wheat was located using single chromosome recombinant lines from the cross between the substitution line Hobbit (Triticum spelta 5A) and Hobbit. In this sample of recombinant lines the locus for frost resistance, designated Fr1, is completely linked to the locus Vrn1 controlling vernalisation requirement. The results can be explained by a pleiotropic action of the Vrn1 locus or close genetic linkage between Vrn1 and Fr1. Further detailed study is necessary to resolve these alternative hypotheses.     

Genotypic control of chromosome pairing in amphiploids involving the cultivated oat Avena sativa L.

Summary A genotype of the diploid species Avena longiglumis (Cw 57) has been shown to modify the genetic control of diploid-like chromosome pairing in the cultivated oat, A. sativa (2n=6x=42) leading to increased homoeologous chromosome pairing in 4x hybrids between the two species (Rajhathy & Thomas, 1974). The Cw 57 genotype has a similar effect in increasing homoeologous chromosome pairing in amphiploids combining diploid and hexaploid genomes including associations between alien chromosomes and their corresponding pairs in hexaploid species. The effect of the Cw 57 genotype is probably in altering the specificity of chromosome pairing in the early stages of meiosis. The use of the Cw 57 genotype to induce homoeologous chromosome pairing as a technique for the transfer of desirable alien variation into the cultivated oat is discussed.     

Breeding for hard red winter wheat cultivars adapted to conventional-till and no-till systems in northern latitudes

Summary Monosomic alien addition lines combining individual F. drymeja chromosomes and the L. multiflorum complement were isolated from the cross between the triploid hybrid L. multiflorum (4x) × F. drymeja (2x) and diploid L. multiflorum (2x). Chromosome pairing in the addition lines was studied at metaphase 1 of meiosis and the relationship between single F. drymeja chromosomes and the corresponding homologous pair in L. multiflorum is discussed. Trivalent frequency in the addition lines was higher than expected from observations of chromosome pairing in the triploid hybrid and there were differences between lines in the number of trivalent associations formed. There is some evidence to suggest that trivalent frequency is not entirely dependent on chromosome length and that transmission of the alien chromosome in the female is dependent on the size of the added chromosome. Morphological studies were made to assess the phenotypic effects of the addition of single F. drymeja chromosomes to the L. multiflorum complement. Two plants (2n=14) with recombination between a L. multiflorum and a F. drymeja chromosome were identified.     

Development of RFLP Markers for Barley

A PstI-based genomic library from barley DNA was screened for RFLPs in the three relatively-distant cultivars ‘Alexis’ (2-row spring type), ‘Igri’ (2-row winter type) and ‘Mammut’ (6-row winter type), digested with BamHI, EcoRI and HindIII. 50 % of the 108 DNA fragments studied represented single-copy sequences, 29 % low-copy and 21 % repetitive sequences. The DNA probes were assigned to discrete barley chromosomes with the aid of wheat/barley addition lines. 80 % of the single- and low-copy sequences hybridized with both barley and wheat DNA, whereas most repetitive sequences gave signals only with barley DNA.     

Cytological analyses of hybrids and derivatives of hybrids between durum wheat and Thinopyrum bessarabicum,using multicolour fluorescent GISH*

The wheat progenitors and other wild relatives continue to be important sources of genes for agronomically desirable traits, which can be transferred into durum wheat (Triticum turgidum; 2n = 4x = 28; AABB genomes) cultivars via hybridization. Chromosome pairing in durum × alien species hybrids provides an understanding of genomic relationships, which is useful in planning alien gene introgression strategies. Two durum cultivars, ‘Lloyd’ and ‘Langdon’, were crossed with diploid wheatgrass, Thinopyrum bessarabicum (2n = 2x = 14; JJ), to synthesize F₁ hybrids (2n = 3x = 21; ABJ) with Ph1. ‘Langdon’ disomic substitution 5D(5B) was used as a female parent to produce F₁ hybrids without Ph1, which resulted in elevation of pairing between durum and grass chromosomes – an important feature from the breeding standpoint. The F₁ hybrids were backcrossed to respective parental cultivars and BC₁ progenies were raised. ‘Langdon’ 5D(5B) substitution × Th. bessarabicum F₁ hybrids were crossed with normal ‘Langdon’ to obtain BC₁ progeny. Chromosome pairing relationships were studied in F₁ hybrids and BC₁ progenies using both conventional staining and fluorescent genomic in situ hybridization (fl‐GISH) techniques. Multicolour fl‐GISH was standardized for characterizing the nature and specificity of chromosome pairing: A–B, A–J and B–J pairing. The A–J and B–J pairing will facilitate gene introgression in durum wheat. Multicolour fl‐GISH will help in characterizing alien chromosome segments captured in the durum complement and in their location in the A and/or B genome, thereby accelerating chromosome engineering research.     

Molecular mapping of QTLs for non-parasitic leaf spot resistance and comparison of half-sib DH populations in spring barley

Quantitative trait loci (QTLs) for resistance against non-parasitic leaf spots (NPLS) were first characterized in a spring barley double haploid population derived from the cross IPZ 24727/Barke (Behn et al., 2004). The aim of the present study was to identify QTLs for NPLS resistance in the half-sibling DH population IPZ 24727/Krona and to compare them with the QTLs of the population IPZ 24727/Barke. An anther culture-derived doubled haploid population of 536 DH lines was developed from the cross IPZ 24727 (resistant)/Krona (susceptible). Field trials were performed over two years in two replications, scoring NPLS and agronomic traits that might interact with NPLS. A molecular linkage map of 1035 cM was constructed based on AFLPs, SSRs and the mlo marker. QTL analyses for NPLS identified three QTLs that accounted for 30% of the phenotypic variation. For comparison of the QTLs from each DH population, a consensus map was generated comprising 277 markers with a length of 1199 cM. In both populations, the QTLs for NPLS mapped to chromosomes 1H, 4H and 7H. A common QTL with a great effect in both populations and over all environments was localized at the mlo locus on chromosome 4H, indicating that the mlo powdery mildew resistance locus has a considerable effect on NPLS susceptibility. The steps necessary to validate the QTLs and to improve the NPLS resistance by breeding were discussed.     

两个二倍体与一个四倍体人工合成三元新棉种

为了将野生比克氏棉的种子无腺体(无棉毒素),而植株上有腺体的珍贵特性,转育到栽培四倍体棉种上。先用栽培二倍体亚州棉(A_2A_2)与二倍体比克氏棉(G_1G_1)杂交成异源二倍体A_2G_1。将杂种染色体加倍,合成异源四倍体A_2A_2G_1G_1。再与栽培四倍体陆地棉杂交,组成三交种合成异源四倍体。并分析了三种杂种的性状遗传学及细胞学。为培育棉、油、蛋白质三位一体的抗虫新棉种,提供了种质。     

中间偃麦草2Ai-2染色体DNA文库构建及特异性序列的克隆

 以二体异附加系Z2与其普通小麦亲本宛7107杂交F1的花粉母细胞为材料,用原位杂交方法确定其中的单价体为中间偃麦草2Ai-2染色体;在此基础上,以显微分离、回收、LA-PCR (Linker-adaptor PCR) 扩增了该条染色体,扩增产物长度在0.15～3 kb之间,主要分布在0.2～2 kb。以α-32P-dCTP标记的中间偃麦草的基因组DNA为探针,对LA-PCR扩增产物进行杂交,证实扩增产物来自中间偃麦草。将扩增片段纯化后连接到质粒载体pUC18上,构建了2Ai-2染色体DNA文库。该文库包含约     

盾叶薯蓣多样性研究进展*

 就盾叶薯蓣的资源多样性主要特点作概要综述:(1)形态结构多样性;(2)生长状况;(3)生理生化特性;(4)染色体倍性变异;(5)同工酶水平与DNA水平遗传的多样性,并对盾叶薯蓣的进一步研究提出了一些建议。     

半夏不同居群的细胞学研究*

 研究采用BSG去壁低渗法，对采集于不同地区、不同居群的半夏(Pinellia ternata)进行细胞学研究。研究结果表明：除文献已报道的半夏属有7，8，9和13四个染色体基数外，本研究发现,该属还存在10和23两个染色体基数，并发现半夏存在2n=75，80，84，66，92，100等染色体数目为本研究首次报道，同时分析讨论了不同居群半夏染色体倍性及数目多样性的关系。