Pathogenicity Analysis on Magnaporthe oryzae from Hybrid Combination Wuyou 308

Eighteen blast isolates were obtained from hybrid combination Wuyou308 using the Magnaporthe oryzae pathogen isolation method.Race identification of these isolates was conducted based on seven Chinese blast differentials and 11 blast monogenic lines.The results indicated that the isolates were identified as the races of ZB13,ZB15 and ZC13,accounting for 66.67%,27.78%,5.56%,respectively,and the resistance genes including Pi-ta2 and Pi-sh,Pi-i were highly susceptible to these isolates,while the resistance genes like Pi-kh,Pi-1,Pi2,Pi-9 and Pi-50 showed good resistance to tested pathogens.All isolates were compatible to the original rice hybrid Wuyou308.Three isolates including GDHY-308-1401 were used for testing their pathogenicity to 45 local varieties.The results demonstrated that 13 varieties appeared highly susceptible to the tested isolates,accounting for 28.89%;two varieties appeared moderately susceptible to the tested isolates,accounting for 4.44%;30 varieties showed moderately/highly resistance,accounting for 66.67%.Among them,some of new hybrid combinations such as Wufengyou 9802,Wuyou 613,Wuyou 1179 showed good resistance to the inoculated strains,and they were recommended to be candidates in the rice region where Wuyou308 showed susceptibility.

Comparative Analysis of the Genomes of Three Field Isolates of the Rice Blast Fungus <i>Magnaporthe oryzae</i>from Southern China

Rice blast caused by Magnaporthe oryzae (M. oryzae) is one of the most destructive diseases, which causes significant rice yield losses and affects global food security. To better understand genetic variations among different isolates of M. oryzae in the nature field, we re-sequenced and analyzed the genomes of three field isolates, QJ08-2006, QJ10-10, and QJ10-3001, which showed distinct pathogenicity on Xin-Yin-Zhan, an elite variety in South China. Genome annotation indicated that these three isolates assemblies have similar genome sizes with 38.4 Mb, 38.3 Mb, and 38.4 Mb, respectively. The QJ08-2006 assembly has 2082 contigs with an N50 of 127.4 kb, the QJ10-10 assembly has 2239 contigs with an N50 of 105.13 kb, the QJ10-3001 assembly has 2025 contigs with an N50 of 133.16 kb. A total of 10,432 genes including 1408 putative secreted protein genes were identified from the annotated isolate QJ08-2006 genome, 10,418 genes including 1410 putative secreted protein genes were identified in QJ10-10, and 10,401 genes including 1420 putative secreted protein genes were identified in QJ10-3001. There are as many as 11,076 identical genes in these three isolates and contained only a few unique genes among three isolates, of which 277 unique genes in QJ08-2006 and 264 unique genes in QJ10-10, and 213 unique genes in QJ10-3001. Most of the predicted secreted protein genes had been identified, and the three re-sequenced strains contained 371, 369, and 387 small Indel, respectively. Avr genes were analyzed in several sequenced Magnaporthe strains, the results revealed that Avr-Pi9 and Avr-Piz-t were present in all the sequenced isolates. The isolates QJ08-2006 contained AvrPib, QJ10-10, and QJ10-3001 had an insertion of a Pot3 element in the promoter of the AvrPib gene. Our results showed that, the rapid dominancy of virulence mutant isolates via clonal propagation displayed in the field after the release of the elite variety Xin-Yin-Zhan.

Research Progress in Molecular Mechanism of Broad-spectrum Disease Resistance in Rice

Yield loss caused by crop diseases seriously restricts global food security.Breeding disease-resistant varieties with resistance(R)genes is acknowledged as the most economical and effective way to control diseases.Therefore,exploring broad-spectrum resistance(BSR)genes to pathogens and clarifying the underlying mechanism are the basis for effective utilization of BSR resources and finding new approaches for disease control.In the past 20 years,significant progress has also been made in plant immune mechanism and remarkable achievements have been made in researches on broad-spectrum disease resistance of major grain crops,and the potential molecular mechanisms of some BSR have been revealed.Here,the advances of broad-spectrum disease resistance in rice(including the representative cloned BSR genes and their molecular mechanisms)were reviewed.In addition,the problems,opportunities and challenges encountered by BSR were analyzed,and the development of BSR research and its application in rice production were prospected.

Synthetical Evaluation on the Qualitative and Quantitative Resistance of Rice Germplasms to Magnaporthe oryzae

[Objectives]This study was conducted to screen out rice resources resistant to rice blast(Magnaporthe oryzae).[Methods]The qualitative and quantitative resistance of 1659 rice resources from 45 countries and regions to rice blast were evaluated by disease nursery in upland condition and the test of the spectrum to rice blast isolates.[Results]There were 292 entries which accounted for 17.6%showed high blast resistance(0 and 1 disease scale),68 entries(counted for 4.1%)showed resistance to blast(3 disease scale);and the number of the entries showed intermediate resistance,intermediate susceptible and susceptible were 208(with the corresponding percentage of 12.5%),471(28.4%),620(37.4%)respectively.Among the tested entries,27 entries including BG1222,BL122,BTX,IR37704-131-2-3-2,and LEBONNET had showed broad-spectrum blast resistance with the resistance frequency of higher than 90%,Quantitative resistance evaluation was conducted on some key resources,and 14 entries,of which are BR27,DRAGO,IR100,QINLIUAI、SERIBU GANTANG,YUEXIANGZHAN and so on,showed good quantitative resistances,and 8 entries had higher quantitative resistances than IR36.[Conclusions]This study provides important blast resistance resources for the local rice breeding program and has a significant value for the discovery of new blast resistance genes and its application in the blast resistance breeding.

Advances in Integrated Control Techniques of Rice Blast

Rice blast is the most devastating disease in rice,and it seriously threatens the safety of rice production.Improving the ability of integrated prevention and control of rice blast has always been an important part of ensuring food production safety.In the past decade,scientists have made great progress in the prevention and control techniques of rice blast,which paves the way for the green controlling of rice diseases.In this article,the advances in the intelligentization of rice blast field monitoring techniques,the optimization of prediction and forecast modeling system,the research and development of low-toxic and high-efficiency chemical pesticides,biogenic pesticides and inducers and the regulation of multiple ecological factors including variety and cultivation are reviewed,and the new strategies for green controlling of rice blast based on these techniques are summarized.Further,the problems such as high pesticide prices and pesticide residue faced by rice blast prevention and control and the challenge of slow research and development of low-toxic and economical biogenic pesticides are discussed.Finally,the development direction of green controlling of rice blast based on molecular targets,small interfering RNA(siRNA)and CRISPR/Cas9 technologies is predicted,with a view to guaranteeing the safety of rice production.

肝细胞腺瘤与肝细胞癌超声造影特征对比

目的对比分析肝细胞腺瘤(HCA)与肝细胞癌(HCC)的超声造影特征差异。方法回顾性分析2014年3月至2019年5月在复旦大学附属中山医院超声科行肝超声造影检查并经病理证实为HCA的30例(共30个病灶)及HCC的56例(共56个病灶)患者的超声造影资料,超声造影动脉期增强方式、包膜下增强血管影、门脉期及延迟期减退变化等方面的差异比较使用χ^(2)检验或Fisher确切概率法。采用诊断四格表评价超声造影征象诊断HCA和HCC的效能。结果HCA和HCC在动脉期均呈高增强,且主要表现为整体增强(86.7%vs94.6%),两者在动脉期增强方式和达峰时均匀性方面比较,差异均无统计学意义(P均>0.05)。动脉期分别有43.3%(13/30)的HCA和8.9%(5/56)的HCC病灶见包膜下增强血管影(χ^(2)=11.971,P=0.001)。在门脉期,HCA呈高增强或等增强的比例高于HCC(13.4%/0vs43.3%/17.9%),差异具有统计学意义(χ^(2)=15.605,P<0.001)。延迟期HCC呈低增强的比例高于HCA(92.9%vs56.7%),差异具有统计学意义(χ^(2)=16.184,P<0.001)。以超声造影“动脉期高增强、门脉期及延迟期低增强”为依据诊断HCC,其敏感度、特异度、准确性分别为92.9%、80.0%、88.4%;以“动脉期高增强、门脉期及延迟期高增强或等增强”或“包膜下增强血管影”任何一种征象为依据诊断HCA,其敏感度、特异度、准确性分别为77.4%、89.1%、84.9%。结论HCA与HCC在超声造影动脉期包膜下增强血管影、门脉期及延迟期增强表现方面有差异,有助于两者的鉴别。