Molecular and Physical Mapping of Powdery Mildew Resistance Genes and QTLs in Wheat: A Review

Wheat powdery mildew （Pro） is a major disease of wheat worldwide. During the past years, numerous studies have been published on molecular mapping of Pm resistance gene（s） in wheat. We summarized the relevant findings of 89 major re- sistance gene mapping studies and 25 quantitative trait loci （QTL） mapping studies. Major Pm resistance genes and QTLs were found on all wheat chromosomes, but the Pm resistance genes/QTLs were not randomly distributed on each chromosome of wheat. The summarized data showed that the A or B genome has more major Pm resistance genes than the D genome and chromosomes 1A, 2A, 2B, 5B, 5D, 6B, 7A and 7B harbor more major Pm resistance genes than the other chromosomes. For adult plant resistance （APR） genes/QTLs, B genome of wheat harbors more APR genes than A and D genomes, and chromo- somes 2A, 4A, 5A, 1B, 2B, 3B, 5B, 6B, 7B, 2D, 5D and 7D harbor more Pm resistance QTLs than the other chromosomes, suggesting that A genome except 1A, 3A and 6A, B genome except 4B, D genome except 1D, 3D, 4D, and 6D play an impor- tant role in wheat combating against powdery mildew. Furthermore, Pm resistance genes are derived from wheat and its rela- tives, which suggested that the resistance sources are diverse and Pm resistance genes are diverse and useful in combating against the powdery mildew isolates. In this review, four APR genes, Pm38/Lr34/Yr18/Sr57, Pm46/Lr67/Yr46/Sr55, Pm？/Lr27/Yr30/ SY2 and Pm39/Lr46/Yr29, are not only resistant to powdery mildew but also effective for rust diseases in the field, indicating that such genes are stable and useful in wheat breeding programmes. The summarized data also provide chromosome locations or linked markers for Pm resistance genes/QTLs. Markers linked to these genes can also be utilized to pyramid diverse Pm resis- tance genes/QTLs more efficiently by marker-assisted selection.

高压力容器开口泄爆过程中压力发展特征的实验研究

建筑物承受高压容器爆炸荷载作用的泄爆设计被日益重视。本文开展了在容积为0.15 m3方形容器中泄爆实验测试。实验装置一端连接高压管道,模拟产生高压爆炸。另一端连接泄爆装置,对不同压力作用的泄爆装置开启过程进行了实验研究。实验结果给出了不同爆炸压力条件下容器内压力发展时程和泄爆装置开启压力、开启时间等指标,对于高压容器的泄爆防护具有工程应用价值。

Construction of Non-infectious SARS-CoV-2 Replicons and Their Application in Drug Evaluation

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has caused a devastating pandemic worldwide.Vaccines and antiviral drugs are the most promising candidates for combating this global epidemic,and scientists all over the world have made great efforts to this end.However,manipulation of the SARS-CoV-2 should be performed in the biosafety level3 laboratory.This makes experiments complicated and time-consuming.Therefore,a safer system for working with this virus is urgently needed.Here,we report the construction of plasmid-based,non-infectious SARS-CoV-2 replicons with turbo-green fluorescent protein and/or firefly luciferase reporters by reverse genetics using transformation-associated recombination cloning in Saccharomyces cerevisiae.Replication of these replicons was achieved simply by direct transfection of cells with the replicon plasmids as evident by the expression of reporter genes.Using SARS-CoV-2 replicons,the inhibitory effects of E64-D and remdesivir on SARS-CoV-2 replication were confirmed,and the halfmaximal effective concentration(EC50)value of remdesivir and E64-D was estimated by different quantification methods respectively,indicating that these SARS-CoV-2 replicons are useful tools for antiviral drug evaluation.

Comparative proteomic analysis of cold responsive proteins in two wheat cultivars with different tolerance to spring radiation frost

Spring radiation frost(SRF)is a severe environmental stress which impairs wheat yield and productivity worldwide.To better understand the mechanism of wheat(Triticum aestivum)responding to SRF,a comparative proteomic analysis was performed to analyze the changes of the key proteins in two wheat cultivars Jimai22 and Luyuan301 with high and low tolerance to SRF respectively.A total of 43 differentially expressed proteins(DEPs)which mainly involved in carbohydrate metabolism,amino acid metabolism,resistance proteins and antioxidant enzymes,photosynthesis and cellular respiration proteins,cell-wall related proteins,protein translation/processing/degradation and signal transduction were isolated and identified by two-dimensional electrophoresis and MALDI-TOF-TOF MS.The results revealed that of the 21 DEPs in Jimai22 responding to the SRF,13 DEPs were upregulated and 8 DEPs were downregulated,and that of the 22 DEPs in Luyuan301,9 DEPs were upregulated and 13 DEPs were downregulated.These DEPs might be responsible for the stronger cold resistance of Jimai22 compared to Luyuan301.The expression pattern and function analysis of these DEPs were very significant to understanding the mechanism of the SRF responses in wheat.

A Novel DT40 Antibody Library for the Generation of Monoclonal Antibodies

Early etiological diagnosis is very important for the control of sudden viral infections,and requires antibodies with both high sensitivity and high specificity.Traditional antibody preparation methods have limitations,such as a long and arduous cycle,complicated operation,and high expenses.A chicken lymphoma cell line,DT40,is known to produce IgM-type antibodies and undergo gene conversion and somatic mutation in the variable region of the immunoglobulin gene during culture.Here,the DT40 cell line was developed to produce antibody libraries and prepare antibody rapidly in vitro.Since hypermutation in DT40 cells was regulated by the activation-induced cytidine deaminase(AID)gene,AID expression needs to be controlled to either fix the Ig sequence by stopping mutation or improve affinity by resuming mutation after the antibodies have been selected.In this study,we generated a novel AID-inducible DT40 cell line(DT40-H7),in which the endogenous AID gene was knocked out using the CRISPR/Cas9 genome editing system,and an inducible AID gene,based on the Tet-Off expression system,was stably transfected.AID expression was controlled in DT40-H7 cells in a simple and efficient manner;gene conversion and point mutations were observed only when AID was expressed.Using the antibody library generated from this cell line,we successfully obtained monoclonal antibodies against the NS1 protein of Zika virus.The DT40-H7 cell line represents a useful tool for the selection and evolution of antibodies and may also be a powerful tool for the rapid selection and generation of diagnostic antibodies for emerging infectious diseases.

A highly efficient in vivo plasmid editing tool based on CRISPR-Cas12a and phage λ Red recombineering

Plasmids are useful tools for studying genetic information in living cells,as well as heterologous expression of genes and pathways in cells(Lauritsen et al.,2018).Various methods have been developed for plasmid manipulation both in vivo and in vitro(Aslanidis and de Jong,1990;Li and Elledge,2007;Xia et al.,2018).However,large plasmids,such as P1-based artificial chromosomes(PACs),bacterial artificial chromosomes(BACs),and fosmids,are difficult to manipulate.

Highlights of special issue on “Wheat Genetics and Breeding”

Wheat is one of the world’s most important food crops and a major constituent of daily calorie and protein intake in humans,thus maintaining sustainable development of wheat production is a globally important issue,particularly for less developed countries.Producing more wheat with better nutrition using less inputs,has become a common objective both for producers and consumers.