摘要：Several methods of interval mapping of QTLs underlying endosperm traits based on random hybridization designs and the triploid genetic model are proposed. The basic idea is: plants (or lines) from a population with known marker genotype information are randomly hybridized to generate a population of hybrid lines for endosperm QTL mapping; a mixture of seeds of each hybrid line is measured for the en- dosperm trait to get the mean of the line; then en- dosperm QTL mapping and effect estimation is per- formed using the endosperm trait means of hybrid lines and the marker genotype information of parental plants (or lines). The feasibility and efficiency of the methods are examined by computer simulations. Results show that the methods can precisely map endosperm QTLs and unbiasedly and efficiently es- timate the three effects (additive effect, first dominant effect, second dominant effect) of endosperm QTLs.

摘要：Genetic transformation in some plant species,including cotton(Gossypium hirsutum), is hampered by laborious and time-consuming processes and often unachievable. Virus-induced gene silencing(VIGS) by double-stranded RNAs can serve as a reverse-genetics tool to determine gene function. However, knockdown levels vary greatly when using a tobacco rattle virus-based vector that carries different c DNA fragments of a gene. How to choose the optional target fragment for high interference efficiency is very challenging. Addressing this challenge requires increasing the efficacy of small interference RNA(si RNA) in target fragment. Here, we describe a method to assess VIGS efficiency by comparing the following parameters of si RNA in target sequence: the disruption energy of the target(DGdisruption), the differential stability of si RNA duplex ends(DSSE), and the internal stability at positions 9–14 of the si RNA antisense strand(AIS), which are calculated by Sfold program(http://***). We find that the si RNAs with low DGdisruption, high DSSE and high AIS have high activity and easily result in high VIGS efficiency by experimentally testing the actual knockdown levels of the four target genes, Gh PDS,Gh CLA1, Gh AOS1, and Gh CXE1 via choosing different target sequences for each gene. Therefore, the Sfold program can be used to analyze target sequences when carrying out VIGS design to increase gene-silencing effects in plants.

摘要：目的:筛选得到多态性好、扩增稳定的条锈菌微卫星标记,以期更好应用于小麦条锈病菌的群体遗传学研究。创新点:基于条锈菌基因组设计了100对候选简单重复序列(SSR)引物,最终筛选得到20对多态性好并且扩增稳定的微卫星标记。方法:基于条锈菌100个组装序列用Primer 5软件设计了100对SSR引物用于检测来自7个国家的32个菌系,最终筛选得到20对较好的微卫星标记(表2)。结论:基于基因组序列筛选得到的20对微卫星标记将会在小麦条锈菌群体遗传研究中得到广泛应用。

摘要：Large amount of pre-plant nitrogen (N) fertilizer results in low N use efficiency due to poor synchrony between soil N supply and maize N demand, especially during N sensitive growth stages. The objectives of the study were to compare growth and yield of maize (Zea mays L.) under conventional and site-specific N management in a dryland farming system. The study, which was designed as randomized complete block design was conducted over three site-years under continuous maize cropping system in the semi-arid regions of the Limpopo Province in South Africa. Treatments of the study consisted of three N management strategies on a maize field planted to drought resistant SNK 2147 hybrid maize cultivar. Treatments were: (i) no N application (N0), (ii) site-specific N at variable rates ranging between 18 kg N/ha and 33 kg N/ha based on soil analysis results (N1) and (iii) conventional and uniform N application broadcasted during planting at 58 kg N/ha (N2). Sufficiency index as indication of N deficiency was determined using CCM-200 on maize leaves based on leaf numbers during maize vegetative growth stages V6, V10 and V14, and thereafter N was applied only when needed. The highest maize grain yield of 5.2 Mg/ha for N1 was significantly higher (P ≤ 0.05) than 3.2 Mg/ha and 4.0 Mg/ha of N0 and N2 in site-year I, respectively. Maize grain yield of 2.2 Mg/ha (N1) at site-year II was significantly higher (P ≤ 0.05) than 1.7 Mg/ha of the N0. The maize growth and yield under N2 and N1 was compared, N1 required between 43% and 69% lesser N fertilizer as compared to N2 over site-years, and resulted in higher maize height, number of leaves per plant, leaf length, and leaf area than that of conventional N management strategy. Therefore, site-specific N management strategy sustains and improves growth and yield of maize using minimal N fertilizer as compared to conventional approach in low fertility soils of semi-arid regions in dryland farming systems. In examining the results of thi

摘要：The long atmospheric residence time of CO2 creates an urgent need to add atmospheric carbon drawdown to CO2 regulatory *** and systems biology(SSB),which enables manipulation of cellular phenotypes,offers a powerful approach to amplifying and adding new possibilities to current land management practices aimed at reducing atmospheric *** participants(in attendance:Christina Agapakis,George Annas,Adam Arkin,George Church,Robert Cook-Deegan,Charles DeLisi,Dan Drell,Sheldon Glashow,Steve Hamburg,Henry Jacoby,Henry Kelly,Mark Kon,Todd Kuiken,Mary Lidstrom,Mike MacCracken,June Medford,Jerry Melillo,Ron Milo,Pilar Ossorio,Ari Patrinos,Keith Paustian,Kristala Jones Prather,Kent Redford,David Resnik,John Reilly,Richard ***,Daniel Segre,Susan Solomon,Elizabeth Strychalski,Chris Voigt,Dominic Woolf,Stan Wullschleger,and Xiaohan Yang)identified a range of possibilities by which SSB might help reduce greenhouse gas concentrations and which might also contribute to environmental sustainability and *** include,among other possibilities,engineering plants to convert CO2 produced by respiration into a stable carbonate,designing plants with an increased root-to-shoot ratio,and creating plants with the ability to self-fertilize.A number of serious ecological and societal challenges must,however,be confronted and resolved before any such application can be fully assessed,realized,and deployed.