Evaluation of the yield and nitrogen use efficiency of the dominant maize hybrids grown in North and Northeast China

Breeding high-yielding and nutrient-efficient cultivars is one strategy to simultaneously resolve the problems of food security,resource shortage,and environmental pollution.However,the potential increased yield and reduction in fertilizer input achievable by using high-yielding and nutrient-efficient cultivars is unclear.In the present study,we evaluated the yield and nitrogen use efficiency(NUE) of 40 commercial maize hybrids at five locations in North and Northeast China in 2008 and 2009.The effect of interaction between genotype and nitrogen(N) input on maize yield was significant when the yield reduction under low-N treatment was 25%-60%.Based on the average yields achieved with high or low N application,the tested cultivars were classified into four types based on their NUE:efficient-efficient(EE) were efficient under both low and high N inputs,high-N efficient(HNE) under only high N input,low-N efficient(LNE) under only low N input,and nonefficient-nonefficient under neither low nor high N inputs.Under high N application,EE and HNE cultivars could potentially increase maize yield by 8%-10% and reduce N input by 16%-21%.Under low N application,LNE cultivars could potentially increase maize yield by 12%.We concluded that breeding for N-efficient cultivars is a feasible strategy to increase maize yield and/or reduce N input.     

HIV Vaccine-Challenges and Opportunities

The need for an efficacious HIV/AIDS vaccine remains the highest priority of the world HIV/AIDS agenda. The generation of an efficacious HIV/AIDS vaccine proves an enormous scientific challenge. This article reviews the neutralizing antibody problem,elusive immune protection,im-munogen design,pre-existing anti-vector immunity and design of phase 3 vaccine trials and the challenges and opportunities in development of HIV/AIDS vaccine are discussed.     

Determination of species-area relationships and minimum sampling area for the shrub communities in the arid valley in the upper reach of the Minjiang River, China

The minimum sampling areas (MSAs) for the shrub communities in the arid valley in the upper reach of the Minjiang River, China, were studied by fitting community species-area relationships using 3 types of equations. The MSAs were determined at the proportional factor (ρ) 0.6, 0.7, 0.8 and 0.9. The proportional factors represent the proportion of the number of species within a sampling plot in the total number of species. The MSAs of the shrub communities at different elevations and on different slope faces for ρ = 0.6, 0.7 and 0.8 were all around 100 m². Hence, the MSAs could be set to be 100 m² (10 m × 10 m) at 60%–80% precision levels. For ρ = 0.9, that is, for a 90% precision level, the MSAs were less than 200 m² (10 m × 20 m). The MSAs and species richness increased gradually with the rising elevation. At the elevation below 2000 m, the MSAs and species richness on the north-facing slope were larger than those on the south-facing slope. However, at the elevation around 2200 m, there was no difference amongst different facing slopes. For the shrub communities in the arid valley in the upper reach of the Minjiang River, the species-area curves by fitting the first two equations are better than that by fitting the third equation.     

利用双启动子表达载体pDH2-YggG-Ptac-Era研究E. coli Era和YggG 蛋白间的相互关系

yggG是从大肠杆菌全基因组文库中钓取并克隆的Era结合蛋白基因,研究表明该基因表达的YggG294(amino acids 1-294)蛋白对宿主菌的生长具有强烈的抑制作用。为了阐明YggG与Era间的相互关系,构建可同时可控性表达Era和YggG294蛋白的双启动子表达载体。利用所构建的双启动子表达载体在同一细胞中同时可控性地表达YggG294与Era蛋白。结果显示,在不表达和少量表达YggG294的细菌细胞内,Era 的表达量与总蛋白量的比值随着诱导时间增加而增高,而YggG294大量表达的细菌内Era 的表达量与总蛋白量的比值基本保持不变;Era 蛋白的预表达对YggG294表达所引起的细菌生长率下降无影响。由此可以推论,YggG294的过表达引起宿主菌生长抑制进而影响了Era蛋白的进一步表达,而YggG294的过表达引起宿主菌生长抑制与YggG和Era蛋白间的相互作用无关     

红花玉兰种质资源遗传多样性初探

采用AFLP分子标记对目前仅发现在湖北五峰狭域分布的红花玉兰种质资源的遗传多样性进行了研究.用10对引物对6个居群的43个个体进行了选择性扩增,共检测到623个有效位点,其中多态位点595个.结果表明:在物种水平上,红花玉兰的遗传多样性水平很高,多态位点百分率达95.51%,Nei s基因多样度(HT)为0.211 0±0.028 6;红花玉兰的遗传变异主要存在于居群内,居群间的遗传分化较小.AMOVA分析表明总变异的93.37%存在于居群内,居群间的变异只占总变异的6.63%.Nei s遗传分化系数(GST)为0.191 9,居群间基因流(Nm)2.105 5.鉴于红花玉兰总体遗传多样性水平很高,而居群数目及居群内个体数量均很少,应该对红花玉兰各居群的所有个体实施及时的就地保护,并对其生境进行保护;并在原产地营建基因保存林,营建时应加大各居群内的取样数量,使得红花玉兰较高的遗传多样性得到保存;同时积极开展异地引种栽培,使红花玉兰在观赏应用中得到切实的保护.     

Ectopic Expression of the Pttknl Gene Induces Alterations in the Morphology of the Leaves and Flowers in Petunia hybrida Vilm.

A novel knottedl-like homeobox （knox） gene, Pttknl （Populus tremulaxtremuloides knottedl）, isolated from the cambial region of hybrid aspen, was introduced into Petunia hybrida Vilm. using the leafdisc method mediated by Agrobacterium. A series of novel phenotypes was observed in transgenic petunia plants, including the formation of ectopic spikes on the adaxial surface of corollas and small petals on the abaxial surface of corollas, fusion of floral organs, shortening of corolla midribs, the formation of tumor-like knots along the midrib on the abaxial surface and serrated lobs of corolla margins, and alterations in petal color; except for changes in the leaves and plant architecture, RT-PCR showed that the Pttknl gene was expressed in the leaves of different petunia transgenic plants, whereas no signal was detected in wild-type plants. The possible function of Pttknl in leaf and flower development is discussed.     

Mapping of a Wheat Resistance Gene to Yellow Mosaic Disease by Amplified Fragment Length Polymorphism and Simple Sequence Repeat Markers

Wheat （Triticum aestivum L.） yellow mosaic virus （WYMV） is transmitted by a fungal vector through soil and causes serious wheat yield losses due to yellow mosaic disease, with yellow-streaked leaves and stunted plants. In the present study, the amplified fragment length polymorphisms （AFLP） and simple sequence repeat （SSR） were used to identify the molecular linkages with the resistance gene against WYMV. Bulked segregant analysis was performed with an F2 population derived from the cross of cultivar Ningmai 9 （resistant） × cultivar Yangmai 10 （susceptible）. By screening among the resistant or susceptible parents, the F2 pools and the individuals in the F2 population with 64 combined selective AFLP primers （EcoRI/MseI） or 290 reported SSR primers, a polymorphic DNA segment （approximately 120 bp） was amplified using the primer pair E2/M5, and an SSR marker （approximately 180 bp） was located on wheat chromosome 2A using the primer Xgwm328. Analysis with MAPMAKER/Exp Version 3.0b （Whitehead institute for Biomedical Research, Cambridge, MA, USA） indicated that these two markers were dominantly associated with the resistance gene at distances of 5.4 cM or 17.6 cM, respectively. The resistance gene to WYMV derived from Ningmai 9, is temporarily named YmNM, and was mapped to wheat chromosome 2A.     

中国刺虎天牛属二新种(鞘翅目,天牛科,天牛亚科)

记述中国刺虎天牛属2新种,即赤红刺虎天牛Demonax rufus sp.nov.和福贡刺虎天牛Demonax fugongensis sp.nov..模式标本保存在西南农业大学昆虫标本馆.     

Pollen Morphology of Eight Genera of the Subtribe Mutisiinae Less. sensu Bremer （Compositae） from Asia

The pollen morphology of 28 species and one variety representing eight genera of the subtribe Mutisiinae Less. sensu Bremer （Compositae） was investigated by scanning electron microscopy （SEM） and light microscopy. The pollen grains are usually radically symmetrical, isopolar, and tricolporate. The shape varies from spheroidal to subprolate in equatorial view and is three-lobed circular in polar view. Based on exine sculpturing observed under SEM, the pollen grains can be divided into three types： （i） type Ⅰ, with macrogranulate sculpture; （ii） type Ⅱ, with a finely granulate sculpture; and （iii） type Ⅲ with spiny sculpture. The palynological data showed that the Macroclinidium Maxim. was remarkably distinguished from those of the other seven genera. The variation of pollen characteristics within the Mutisiinae in Asia is little at species level, but it proves some useful information for studying the relationships among genera and it has an important significance in further understanding the evolutionary history of Mutisiinae.