汞毒性对草木樨（Melilotus officinalis）幼苗基因型的差异性抑制研究

采用水平淀粉凝胶电泳技术对草木樨（Melilotus officinalis）的磷酸葡萄糖异构酶（Pgi）和苹果酸酶（Me）进行了基因频率分析。所研究的草木樨种群具有较高的多态性（A=3.0,Ho=0.346～0.401）,将草木樨种子暴露于HgCl2溶液（30mg·L-1）,萌发后测量各幼苗的上、下胚轴长度以及测定其基因型,判定各基因型与上、下胚轴长度的关系。ANOVA分析表明,对照组中Me-AA基因型幼苗具有下胚轴生长优势,Me-AA基因型个体的下胚轴长度（35.20mm±4.63mm）显著大于以下各基因型个体的下胚轴长度：Me-AB（22.84mm±1.34mm）,Me-BB（22.82mm±0.68mm）和Me-BC（20.00mm±1.21mm）。HgCl2急性暴露对Me各基因型下胚轴的抑制作用呈现均一性。在Pgi基因座,草木樨对照组中各基因型的生长不存在差异,但在HgCl2急性暴露下,Pgi-AC基因型幼苗的下胚轴长度（19.75mm±0.73mm）显著大于Pgi-BB基因型的下胚轴长度（14.67mm±1.04mm）,表明Pgi-AC基因型个体对HgCl2的耐受性更强。等位酶分析技术可用来确定植物的种群遗传结构对生长或重金属的耐受性关系，这种关系的确立对遗传育种、生态修复具有潜在的应用价值。     

基因组学发展对传统林木遗传改良的影响

通过对传统林木遗传改良的成就进行概述,分析了基因组研究的发展对传统林木遗传育种的影响,基因组时代的林木遗传改良方法。研究结果表明,传统的林木遗传改良在提高林木生长量和抗性等选育方面取得了显著的成果,单一或者几个树种成为一个国家或地区的主要造林树种成为可能;基因组学的发展从基因的水平对认识林木的遗传本质提供了信息,也丰富了传统遗传改良的方法和手段,必将加速林木遗传育种的进程;基因组学只是辅助传统林木遗传育种的工具,不可能替代传统林木遗传改良理论、方法和技术。     

Trial heterogeneity and variance models in the genetic evaluation of potato tuber yield

Genetic evaluation aims to identify genotypes with high empirical breeding values (EBVs) for selection as parents. In this study, 2157 potato genotypes were evaluated for tuber yield using 8 years of early‐stage trial data collected from a potato breeding programme. Using linear mixed models, spatial parameters to target greater control of localised spatial heterogeneity within trials were estimated and variance models to account for across‐trial genetic heterogeneity were tested. When spatial components improved model fit, correlations of errors were mostly small and negative for marketable tuber yield (MTY) and total tuber yield (TTY), suggesting the presence of interplot competition in some years. For the analysis of multi‐environment trials, a variance model with a simple correlation structure (with heterogeneous variances) was the most favourable variance structure fitted for TTY and PTY (per cent marketable yield). There was very little difference in model fit when comparing a factor analytic structure of order 2 (FA2) with either FA1 or simple correlation structures for MTY, indicating that simple variance models may be preferable for early‐stage genetic evaluation of potato yield.     

棉属野生棉与栽培棉种间杂交新种质创造研究

棉属(Gpssypium)野生资源具有的抗病、虫,抗旱及优质纤维等遗传特性,通过种间杂交可转育到栽培棉,以丰富和改善现有栽培棉品种的遗传特性或创造新的优异种质材料供育种利用。本文报道用23个棉属的野生种与4个栽培种的品种杂交,获得不同世代的47个组合杂种,并从一部分杂种后代培育出一批抗病、虫,抗旱和纤维高强优质等遗传特性的新种质。同时研究了有关种间杂交的不亲和性、杂种F_1的遗传性状以及细胞遗传学、胚胎学等问题。     

Response to long-term selection in early maturing maize synthetic varieties

Long-term continuous selection is essential for germplasm improvement. However, choice of germplasm for long-term genetic improvement might limit the success of germplasm enhancement programs. The objective of this research was to report the response to long-term selection in early maturing North Dakota (ND) synthetic varieties. We wanted to determine whether the performance of three ND maize synthetic varieties was improved by long-term mass selection (M) and if the performance of one of them was improved by long-term modified ear-to-row (MER) selection. The evaluation of long-term selection response was performed at two plant densities. An experiment in a randomized complete block design with split-plot arrangement was used to evaluate NDSM(M), NDSAB(M), NDSCD(M), and NDSAB(MER) under 75,000 and 42,500 plants per hectare across seven environments. Long-term mass selection for grain yield and stalk lodging resistance in NDSM(M), NDSAB(M), and NDSCD(M) was not successful, since there were no significant changes in grain yield or stalk lodging in these populations at either low or high densities. On the other hand, long-term modified ear-to-row selection was effective for grain yield improvement in NDSAB(MER). Grain yield increased non-linearly from 3.9 Mg ha⁻¹ in cycle 0 to 5.0 Mg ha⁻¹ in cycle 12 at a rate of 2.5% per cycle. Interaction between plant density and genotype was not detected even though selection was performed at relatively low densities (20,000 plants ha⁻¹ for mass selection and 50,000 plants ha⁻¹ for ear-to-row selection). The confirmation of a lack of interaction between plant density and genotype suggests that selection at low plant densities might still be able to provide high-density stress resistance through density-independent genotypes, allowing progeny testing across multiple locations with better accuracy and fewer resources. Selection methods that emphasize both additive and dominance effects such as full-sib recurrent selection are recommended to maximize genetic improvement of advanced population cycles of early maturing synthetics.     

小麦花培育种技术研究

对5个小麦不同组合基因型的F1,F2,F3花药进行培养,结果表明:不同组合基因型在同一杂种世代的花药愈伤组织诱导率、愈伤组织鲜重和绿苗分化率等方面存在较大差异,而同一组合基因型在不同杂种世代的花药愈伤组织诱导率、愈伤组织鲜重和绿苗分化率等方面差异较小。花药愈伤组织诱导率与绿苗分化率具有显著的相关性(r2=0.903)。以石4185为亲本配制的两个组合基因型,在F1,F2,F3都表现出较高的花药愈伤组织诱导率和绿苗分化率,说明石4185是理想的花培育种桥梁亲本。     

Pattern analysis of genotype × environment interaction for striga resistance and grain yield in African sorghum trials

The parasitic weed Striga hermonthica (Del.) Benth. seriously limits sorghum [Sorghum bicolor (L.) Moench] production in Sub-Saharan Africa. As an outbreeder, S. hermonthica is highly variable with an extraordinary capacity to adapt to different hosts and environments, thereby complicating resistance breeding. To study genotype x environment (G x E) interaction for striga resistance and grain yield, nine sorghum lines, 36 F₂ populations and five local checks were grown under striga infestation at two locations in both Mali and Kenya. Mean squares due to genotypes and G x E interaction were highly significant for both sorghum grain yield and area under striga severity progress curve(ASVPC, a measure of striga emergence and vigor throughout the season). For grain yield, the entry x location-within-country interaction explained most of the total G x E while for ASVPC, entry x country and entry x location-within-country interactions were equally important. Pattern analysis (classification and ordination techniques) was applied to the environment-standardized matrix of entry x environment means. The classification clearly distinguished Malian from Kenyan locations for ASVPC, but not for grain yield. Performance plots for different entry groups showed differing patterns of adaptation. The ordination biplot underlined the importance of entry x country interaction for ASVPC. The F₂ derived from the cross of the striga-resistant line Framida with the striga-tolerant cultivar Seredo was the superior entry for both grain yield and ASVPC, underlining the importance of combining resistance with tolerance in striga resistance breeding. The observed entry x country interaction for ASVPC may be due to the entries' different reactions to climatic conditions and putative differences in striga virulence in Mali and Kenya. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of Genotypes and Plant Density on Yield, Yield Components and Photosynthesis in Bt Transgenic Cotton

Bt (Bacillus thuringiensis) transgenic cotton (Gossypium hirsutum L.), including the introduced, indigenous Chinese non‐hybrid and hybrid cotton, is spreading very rapidly in China. Agronomic and photosynthetic performance as well as the optimum plant density for planting Bt cotton may vary with genotypes. With three types of commercial Bt cotton varieties, two field experiments were conducted to study yield performance and leaf photosynthetic rate (Pn) during 2000 and 2001, and yield interaction between variety and plant density during 2001 and 2002 in Yellow River region in northern China. The first experiment showed that the indigenous Chinese Bt cotton significantly differed from the introduced Bt cotton (IBtC) in plant growth and yield components. As a result of manipulation of boll numbers, boll weight and lint percentage, there was no significant difference in lint yield between Chinese non‐hybrid Bt cotton (CBtC) and the IBtC, but two Chinese hybrid Bt cotton (HBtC) varieties exhibited significantly higher lint yield than all other varieties in either 2000 or 2001. Hybrid cotton SCRC15 showed a one‐peak curvilinear change in diurnal course of Pn throughout the growing season, while non‐hybrid cotton 33B and SCRC16 exhibited severe mid‐day depression in Pn in squaring, flowering or boll‐setting stage. The second experiment showed that the main effect of plant population on lint yield was not significant, and yield difference among all treatments was derived from varieties and the interaction between plant density and variety. The optimal plant densities in terms of lint yield for the introduced, indigenous CBtC and HBtC genotypes were 6.0, 4.5 and 3.0 plants m^?2 respectively.     

Comparison of doubled haploid lines and F2 bulks for the improvement of barley in the dry areas of North Syria

Drought stress is the main factor limiting barley yields in West Asia and North Africa. This study compares the utility of doubled haploid lines (DHLs) and conventional F₂ plant-derived bulks (F₂Bs) in improving barley in stress environments. Double crosses were made, DHLs were developed by anther culture from double-cross F₁ plants, and F₂Bs were produced by bulking the offspring of F₂ plants. Field tests were conducted in three drought-stressed environments. No major differences were observed in the mean performance of DHLs and F₂Bs. For most traits, both the genotypic and the genotype × location interaction variances were higher in the DHL group, whereas heritabilities were similar. Higher gains from selection were predicted for the DHL group. Regression analysis of yield stability indicated a lower predictability of the DHL performance. The haploid technique can improve breeding populations from which varieties with stable yields can be developed. The costs involved are determined by the DHL production rate, which needs to be improved in many developing countries.     

Yield and adaptation of hexaploid spring triticale

Summary Gains in yield and stability were analysed using grain yield data from the 8th to the 14th International Triticale Yield Nursery (ITYN) and differences in adaptation between complete and substituted triticales (X Triticosecale Wittmack) were examined. A trend of improving yield and adaptation was observed. As highly significant genotype × site interaction each year was not adequately described using regression analysis, yield stability was examined by ranking genotypes within sites and summarizing scores for individual genotypes across sites. Cluster analysis was used to study the relationships among sites and among genotypes. There was little evidence of sites grouping on a geographical basis. Grouping of genotypes showed a tendency for complete and substituted triticales to perform differently, suggesting that diversity for adaptation is maximized by utilizing both types in breeding.Progress for grain yield is compared with more spectacular gains in test weight and reasons for the different rates of improvement are postulated.Abbreviations CIMMYT International Maize & Wheat Improvement Centre - ITYN International Triticale Yield Nursery contribution from CIMMYT/Agriculture Canada (No. R-002)