动物分子育种：一门发展中的新型学科

动物分子育种的理论基础是分子遗传学和分子数量遗传学，操作方法依赖于ＤＮＡ重组技术，同时也将结合一些经典的育种技术。分子育种的目标不仅仅是改良畜禽的重要生产性状，也将创造一些非常性经济性状。本文简要地介绍了动物分子育种的主要研究内容及其发展现状，也提出了在育种实践应用分子育种的策略与方法，这将有助于我国在动物分子育种领域内积极地进行探索。     

SNP分子标记及其在甘蓝型油菜中应用的研究进展

甘蓝型油菜(Brassica napus,AACC,2n=38)是中国种植面积最大的油料作物.单核苷酸多态性(single nucleotide polymorphism,SNP)分子标记作为最重要的分子标记技术对正向遗传学研究有极其重要的作用.过去五年,白菜(Brassica rapa)、甘蓝(Brassica oleracea)以及甘蓝型油菜的基因组序列的组装完成,更增大了SNP分子标记在油菜中的研究潜力.本文分析了SNP的生物性质及其技术研究,回顾SNP在甘蓝型油菜中的应用现状,重点关注SNP在连锁图谱构建以及关联分析中的应用,同时,综述了SNP在甘蓝型油菜种质资源分析、群体进化分析,以及分子标记辅助育种等方面的众多应用,旨在为理解和研究SNP分子标记在甘蓝型油菜中的应用提供参考.     

利用BSA-Seq方法快速定位作物农艺性状QTL/基因概述

为了利用生物学技术和手段来解决农业问题,让基因组测序技术、转基因及基因编辑等现代分子生物学技术为农业遗传育种服务,实现常规育种与分子设计育种的紧密结合,加速作物精准育种进程,近年颇受学术界关注。现梳理了一些分子生物学专用名词概念,概述了目前在正向遗传学研究中如何利用极端表型材料基于全基因组测序的BSA-Seq方法(MutMap法、MutMap+法、MutMap-Gap法、QTL-seq法)快速定位重要农艺性状的QTL/基因,为快速定位和克隆候选基因提供新思路。     

表观基因组时代

DNA双螺旋结构的发现和重组DNA技术、PCR技术的产生极大的促进了分子遗传学的发展。几十年来,DNA一直被认为是决定生命遗传信息的主要物质。但是,大量的事实表明,生命遗传信息从来就不是基因所能完全决定的。例如,同卵双生的双胞胎具有完全相同的基因组,在相同的环境下长大后,他们在性格、健康等方面都会有较大的差异,这并不符合经典遗传学理论预期的情况,让人产生疑问;     

分子标记辅助选择在作物育种中的应用及展望

分子标记辅助选择(Marker-assisted-selection；MAS)是作物遗传改良的有效工具。随着高通量低成本SNP标记的开发应用和生物信息学的快速发展，MAS的应用拓展到了全基因组选择(Genomic Selection，GS)，大大地提高了选择的效率和精准性。因技术和费用的限制，MAS未能广泛应用。为拓展MAS在作物育种中的应用路径，并发挥其最大潜力。通过查阅相关文献，综述了MAS在作物育种中的优势及其应用途径；分析了MAS应用受限的原因所在，并针对具体问题提出了对策；预测了MAS的应用前景:因高通量基因分型及基因组测序技术等的快速发展，未来MAS费用肯定显著降低，选择效率将大幅提升，致使MAS的应用空间更为广阔。     

RAPD技术在基因组指纹图谱构建研究中的应用

遗传图谱的建立，是遗传学研究中一个很重要的领域，是对基因组进行系统性研究的基础，也是遗传育种的依据。９０年代发展起了一种ＤＮＡ多态性分析的新方法－ＲＡＰＤ技术，克服了以往ＲＦＬＰ和ＰＣＲ技术的很多缺陷，已被广泛应用于基因组研究的各个方面。文中介绍了ＲＡＰＤ技术的原理，研究成果，以及未来展望。     

农业生物信息学

20世纪80年代末，人类基因组计划(Human Genome Project，HGP)的启动推动了生物信息学的产生和蓬勃发展。人类基因组计划的直接结果是获得了大量不连续的数据。对这些数据的收集、存储、分析和解释，从中获取有用的生物学信息，导致了生物信息学的产生。生物信息学在农作物基因组分析中的深入应用产生了农业生物信息学，本文在介绍生物信息学理论和国内外研究进展的基础上，分析了生物信息学在农作物育种及农作物基因组学等方面的应用前景，提出了我国农业生物信息学的研究和开发建议。     

全基因组关联分析在作物育种研究中的应用

全基因组关联分析(GWAS)是一种针对全基因组范围内的遗传变异进行基因分型,寻找某一群体内性状与分子标记或候选基因间关系的分析方法。GWAS对于连锁标记开发、目的基因挖掘和复杂性状的遗传研究具有重要作用,在作物数量性状研究和作物育种中得到了广泛的应用。本文简要综述了利用GWAS挖掘与作物重要性状关联基因的研究过程中,群体结构、群体数量、连锁不平衡(LD)等因素对GWAS的影响,并重点分析了GWAS在粮食作物育种研究中取得的最新进展,初步讨论了GWAS对作物遗传育种的意义、存在的问题和未来发展趋势等,为利用GWAS在作物育种方面的运用,促进作物分子标记辅助育种以及提高育种效率提供了一定的理论依据。     

观赏植物远缘杂交后代的鉴定方法

远缘杂交是观赏植物种质创新和品种改良的重要方法,但远缘杂交易出现假杂种,对远缘杂交后代进行杂种真实性鉴定、筛选出目的杂种在观赏植物远缘杂交育种中具有重要作用。本文简要介绍了观赏植物远缘杂交后代中假杂种的可能产生途径,详细阐述了形态特征、细胞遗传学、分子细胞遗传学、分子标记、生理生化指标等主要方法在观赏植物远缘杂种鉴定上的研究进展,重点总结了FISH、GISH等原位杂交技术和RAPD、AFLP、SSR等分子标记鉴定方法的应用情况;并提出观赏植物远缘杂交育种中杂种真实性鉴定方法的选择策略,对未来的发展方向进行展望,以期为相关研究提供参考。     

全基因组测序(WGS)在畜禽群体进化和功能基因挖掘中的应用

全基因组测序(whole genome sequencing,WGS)是指通过高通量测序技术对物种个体或群体的基因组进行测序,并通过生物信息学技术对序列特征进行分析,以在全基因组水平探究物种的进化规律和筛选功能基因,主要包括从头测序(de novo)和重测序(re-sequencing).WGS具有信息全面、精确、高效等优点,尤其能对未知基因和未知结构变异进行高效探索,随着高通量测序技术的发展,WGS成本快速降低,使其迅速超越传统策略,成为当前群体进化分析和功能基因挖掘的最主要研究策略,并在畜禽中得到广泛应用.目前已经对鸡(Gallus gallus)、猪(Sus scrofa)、牛(Bos taurus)、绵羊(Ovis aries)、山羊(Caprahircus)、马(Equus caballus)、鸭(Anas platyrhynchos)和狗(Canis lupus)等畜禽进行了大量WGS研究,探究了畜禽进化规律,并挖掘出许多关键功能基因.此外,WGS在未来畜禽泛基因组的构建和全基因组选择育种中也将有广泛的应用.本文主要对WGS的特征和发展进行了介绍,概述和讨论了其在畜禽群体进化和功能基因挖掘中的应用,并简述了其关键要点和应用前景,以期为WGS在畜禽中得到进一步的应用提供理论参考.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Aircraft operations near concentrations of birds in Antarctica: The development of practical guidelines

Aircraft operations have the potential to disturb and to impact negatively on bird life. A gradient of increasing behavioural response is evident in birds when exposed to increasing aircraft stimulus. The most major disturbance is likely to lead to impacts on the health, breeding performance and survival of individual birds, and perhaps bird colonies. A process of revision to policies on aircraft operations contained in management plans for a number of specially protected areas in Antarctica by the United Kingdom, accompanied by consultations made within the scientific community through the Scientific Committee on Antarctic Research (SCAR) and with operational interests through the Council of Managers of National Antarctic Programmes (COMNAP) resulted in new guidelines being adopted by the Antarctic Treaty Consultative Parties in June 2004. The principal recommendations of the guidelines are that bird colonies should not be overflown below 2000 ft (∼610 m) above ground level and landings within 1/2 nautical mile (∼930 m) of bird colonies should be avoided wherever possible. These guidelines are less stringent and less specific than those that were recommended by the SCAR specialist group on birds, and represent a compromise to accommodate operational needs. While the adoption of clear and consistent guidelines for the operation of aircraft in Antarctica is welcome in that this provides practical advice that is likely to reduce incidences of close aircraft/bird encounters, there remains insufficient knowledge of the interactions between aircraft and birds in Antarctica, and the consequent impacts on individual birds and on bird populations. It is important, therefore, that the guidelines adopted are considered interim, and should be kept under scrutiny with revisions made as new and improved research results appear.     

The abundance of heterocystous blue-green algae in rice soils and inocula used for application in rice fields

Summary Algal populations were quantified (as colony-forming units [CFU] per square centimetre) in 102 samples of rice soils from the Philippines, India, Malaysia and Portugal, and in 22 samples of soil-based inocula from four countries. Heterocystous blue-green algae (BGA) were present in all samples. Nostoc was the dominant genus in most samples, followed by Anabaena and Calothrix. In soils, heterocystous BGA occurred at densities ranging from 1.0 × 10² to 8.0 × 10⁶ CFU/cm² (median 6.4 × 10⁴) and comprised, on average, 9% of the total CFU of algae. Their abundance was positively correlated with the pH and the available P content of the soils. In soil-based inocula, heterocystous BGA occurred at densities ranging from 4.6 × 10⁴ to 2.8 × 10⁷ CFU/g dw (dry weight), comprising only a moderate fraction (average 13%) of the total algae. In most soils, the density of indigenous N₂-fixing BGA was usually higher than that attained by applying recommended rates of soil-based inoculum. Whereas research on the practical utilization of BGA has been mostly directed towards inoculation with foreign strains, our results suggest that attention should also be given to agricultural practices that enhance the growth of indigenous strains already adapted to local environmental conditions.Maître de Recherches ORSTOM (France), Visiting Scientist at IRRI