地衣芽孢杆菌GXN151的纤维素酶基因cel9A的序列分析及cel48A的定位

运用底物筛选法从地衣芽孢杆菌GXN151的基因文库中筛选到3类表达羧甲基纤维素酶活性的克隆。对克隆pGXNP11的测序表明其含有纤维素酶基因cel9A和cel48A的部分序列熏cel9A基因为1899bp熏可编码含633个氨基酸的内切葡聚糖酶cel9A熏cel9A的N-末端第21~456氨基酸形成家族9糖基水解酶催化功能域,第480~565氨基酸为家族3碳水化合物结合组件功能域,cel48A基因位于ce19A基因的下游,两者可能共用一个操纵子。cel48A基因编码一个外切纤维素酶熏通过染色体步移法将cel48A定位于4kbEcoRI片段上或10kbSalI片段上。     

Inter-varietal chromosome substitution lines in wheat — revisited

Summary The difficulties in developing inter-varietal chromosome substitution lines in wheat are reviewed. The use of genetical, cytological and molecular markers is suggested as a way of overcoming them. These difficulties and the use of markers, as well as the need to develop duplicate lines to detect background variation, are described using the development and analysis of the Cappelle-Desprez (Bezostaya 1) chromosome substitution set as an example. The effects of substituting Bezostaya 1 chromosomes on final plant height and adult-plant resistance to yellow rust are reported. The large number of aneuploids and substitution lines available in wheat provides a tremendous, international resource, which should be exploited in the future.     

In vitro chromosome doubling of Miscanthus sinensis

The aim was to develop an efficient chromosome doubling method for Miscanthus sinensis to enable the production of triploids and so avoid seed dispersal to the environment. Antimitotic treatments with colchicine or oryzalin were tested in M. sinensis cl. MS‐88‐110 on: (1) in vitro shoots and plants established in soil; (2) during propagation of embryogenic callus; and (c) during the initial stages of callus induction. All systems produced chromosome‐doubled plants. A higher percentage of tetraploids was found after antimitotic treatment at the explant or callus level compared with treatment of in vitro shoots or plants established in soil. In general, oryzalin was more toxic to plant material than colchicine. A higher frequency of chimeras was found among plants with altered ploidy level when the target was formed shoot buds compared with adventitious shoot formation from callus. Antimitotic treatment of embryogenic callus from shoot apices also resulted in a high degree of albinism.     

The origin of lentil and its wild genepool

Summary Following hybridization experiments and cytogenetic analysis of interspecific hybrids three chromosome interchanges were found between the cultivated lentil L. culinaris and L. nigricans, and only one between the cultivated species and L. orientalis. This indicates that the latter species is more likely to be wild progenitor of lentil. The partial fertility of the interspecific hybrids indicate further that both L. nigricans and L. orientalis should be included in the wild genepool of lentil, and their variation can be exploited by relatively simple hybridization techniques. The wild lentils L. orientalis and L. nigricans are morphologically very similar but reproductively strongly isolated from one another by the albino seedling of their hybrids. It has been suggested that the populations of L. orientalis that gave rise to the cultivated lentil still possess a similar chromosome arrangement as in L. culinaris and are also capable of forming normal hybrids with L. nigricans. According to these considerations it is unlikely that lentil originated from populations at the south western corner of the distribution area of L. orientalis.     

North European cultivars as donors of resistance to American gooseberry mildew in black currant breeding

Summary The Swedish black currant Öjebyn is heterozygous for a dominant gene, designated Sph2, conferring effective resistance against Sphaerotheca mors-uvae at East Malling. Resistance due to the gene M derived from the Finnish Brödtorp is now often only partial and in some progenies is associated with an undesirable spreading habit. Size differences in the satellites of the two nucleolar chromosomes of Brödtorp are not closely associted with differential mildew response in its derivatives.     

Cytogenetic Studies of Different Miscanthus Species with Potential for Agricultural Use

Four morphologically different clones of Miscanthus sinensis‘Giganteus’, presently grown in Austria, one ornamental, M. sinensis, and two cultivars of M. sacchariflorus, were studied to determine their chromosome number, chromosome morphology and meiotic behaviour. The clones of M. sinensis‘Giganteus’ uniformly showed a somatic chromosome number of 57. The ornamental M. sinensis, and one M. sacchariflorus cultivar had 38 and the second M. sacchariflorus genotype had 76 chromosomes. While the ornamental M. sinensis exhibited a regular meiosis with predominantly ring bivalents, M. sinensis‘Giganteus’ displayed a highly irregular meiosis with stickiness, frequent occurrence of trivalents and a large number of laggards in both the first and second anaphases. The presence of two satellited chromosomes suggests an allotriploid genome constitution; the trivalents indicate the involvement of closely related species in the amphiploid. Triploidy of the plants is supposed to be the major cause of their sterility. Suggestions are made for further cytogenetic studies including genome analysis and an attempt to resynthesize M. sinensis‘Giganteus’ to provide an insight into the genetic architecture of the plant and to generate new genetic variations for breeding purposes.     

马铃薯高效染色体加倍方法建立与抗寒资源创制

In this work, different treatment combinations including colchicine concentrations and treatment methods as well as different time points was used to investigate the survival rate and chromosome doubling efficiency of potato tissue culture plantlets. The potato chromosome doubling by using colchicine had been successfully optimized. The potato plantlet stems treated with 0.1% colchicine for three days shaking at 120 r min^-1 showed the highest doubling efficiency due to its better contact to the colchicine solution. Compared with other potato chromosome doubling techniques, this method has much higher chromosome doubling rate, shorter time treatment and easier to operate, so that it could provide a higher efficient method for potato ploidy operation. In the meantime, compared with the diploid, the tetraploid interspecific hybrids showed differences in the morphological characteristic, which had higher plants, thicker stem, bigger petals and pollen grain. In addition, no significant difference was found between diploid and tetraploid interspecific hybrids in terms of cold resistance, but both significantly enhanced cold resistance compared with the common potato cultivar. Taken together, the doubled interspecific hybrids could sever for improving cold resistance of potato cultivars.     

Genomic constitution of Festulolium cultivars released in the Czech Republic

Genomic in situ hybridization (GISH) was used to characterize the chromosome constitutions of individual plants from a set of tetraploid and hexaploid cultivars of Festulolium developed and released in the Czech Republic from hybrids of Lolium multiflorum with Festuca pratensis and F. arundinacea. A simplified GISH protocol readily discriminated parental genomes in the hybrids and facilitated the screening of large numbers of plants per accession. The contribution of parental genomes in the cultivars tested ranged from predominance of chromatin from one of the parents to a more balanced contribution from both parents. However, in none of the cultivars were equal proportions of chromatin from both parents present. The parental contribution to the hybrids was both in the form of complete chromosomes or as chromosome translocations. In hexaploid cultivars from (L. multiflorum × F. arundinacea) × F. arundinacea hybrids the average numbers of complete L. multiflorum chromosomes ranged from 4.95 to 7.5 and the numbers of translocations from 6.33 to 10.21. Two tetraploid cultivars from (L. multiflorum × F. arundinacea) × L. multiflorum hybrids showed a strong prevalence of L. multiflorum chromatin and intergeneric translocations were rare. In the tetraploid cultivar ‘Perun’ of the L. multiflorum × F. pratensis hybrid there were 11.7 chromosomes of L. multiflorum and 14.7 recombined chromosomes on average. Reasons for the domination of one of the parental genomes in hybrid cultivars are not clear and are only partially explained by breeding history. Recombination rates of individual genomes in hybrids involving F. arundinacea were evaluated in double hybridization experiments. The results indicated a strong affinity of the L. multiflorum genome for the F. pratensis genome present in F. arundinacea and little affinity for the F. glaucescens genome. This suggests that introgressions from F. arundinacea into L. multiflorum are primarily limited to the F. pratensis genome which can be more readily accessed in L. multiflorum × F. pratensis hybrids.     

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.