江西稻瘟病菌稻巨座壳致病性分化年度动态变化

为明确江西水稻种植区稻巨座壳菌（稻瘟病病菌）的年际变化规律,本研究采用7个中国鉴别寄主与30个单基因鉴别品系两套鉴别寄主分别鉴定分析了2006-2018年间从江西37个水稻主要种植县市分离的1 161个稻瘟病单孢菌的生理小种、致病力、致病类型与无毒基因型等。研究结果表明,江西稻瘟病菌可以分成7群49个生理小种,其中ZA、ZB、ZC群为优势种群,ZB13为优势小种,出现频率为18.00%,以毒性较强的强致病力菌株为主;江西稻瘟病菌在生理小种构成、优势小种、致病力年际变化方面均具有3-5年的周期性;江西历年稻瘟病菌的致病类型较为丰富且存在年度差异,菌株致病类型占各年度总菌株数的82.79%-98.21%,优势致病型菌株占当年总菌株的3.57%-5.77%;历年稻瘟病菌的无毒基因个数为24-29个,其中Avr-Pizt、Avr-Piz5、Avr-Pik、Avr-Pik(C)在历年供试菌株中出现频率较高,说明与之相对应的抗瘟基因在江西抗病育种与抗性品种布局中具有较好的应用价值。     

稻瘟病菌重复顺序PoR6和稻瘟病菌的分型

POR6是一具有高度多态性的稻瘟病菌(Pyricularia oryzae)重复顺序。利用脉冲电泳技术和Southern分析,表明它是非均匀地散布于基因组中的。经测定POR6的拷贝数约为30—40,序列测定未发现在内部有更小的重复单位。用POR6作探针对44株稻瘟病菌进行DNA指纹分析,分析的中国北方地区的22个菌株可根据相似率归并成8个谱系。对一些转管培养中致病型发生变化的菌株用POR6进行指纹分析,发现这些菌株在转管过程中基因组DNA是有变化的。     

江苏省稻瘟病菌的毒性多样性及水稻品种的抗病性

在13个已知日本抗病基因品种上检测1997－1999年采集自江苏省吴江,赣榆,通州,高邮和宜兴等5个代表地区的324个稻瘟病菌株的毒性,结果可将上述菌株划分为90种毒性类型,表明江苏省稻瘟病菌存在着丰富的毒性多样性,毒性类型组成在地区间存在较大的差异,并且随着时间的推移,稻瘟病菌毒性类型组成有差异加大的趋势,在已知抗病基因品种上测定江苏省稻瘟病菌的毒力,结果显示：Pi-k^3,Pi-ta,Pi-ta^2和Pi-sh等抗病基因对江苏省的稻瘟病菌的抗谱很窄,而Pi-i,Pi-z,Pi-z^t和Pi-b等抗病基因的抗谱比较宽,可作为抗源加以利用,用6个代表性毒性类型菌株接种江苏省80筱水稻主载品种和新育成品种,品种抗性分析表明,上述水稻品种中的籼稻和杂交稻对江苏省稻瘟病菌具有较高的抗性,而粳稻品种的抗性较差,上述研究结果为利用水稻品种抗性多样性控制稻瘟病提供了依据。     

辽宁省白头翁叶斑病菌的遗传多样性

白头翁叶斑病是近年来我国新报道发生的一种白头翁叶部病害,在辽宁省保护地白头翁生产中病害尤为严重.对采自辽宁省5个白头翁主产区的25株白头翁叶斑病菌(Ascochyta anemones)菌株及中国农业科学院惠赠的5个壳二孢属(Ascochyta spp.)菌株进行RAPD分析.结果表明:11条随机引物共扩增得到条带清晰并呈多态性的108条谱带,单个引物扩增DNA片段集中分布在200～ 2000 bp.采用NTSYS软件进行病原菌的聚类分析,发现供试的30株壳二孢菌的遗传相似系数为0.56～0.98,当相似系数为0.62时,30个菌株被划分为4个类群,说明辽宁省白头翁叶斑病菌具有丰富的遗传多样性.RAPD遗传聚类组群与白头翁叶斑病菌菌株的地理来源有一定的相关性,不同寄主来源的菌株之间存在明显的遗传差异.     

水稻品种多样性田间稻瘟病菌群体遗传结构分析

利用稻瘟病菌的一段倒位重复序列Pot2设计的一对引物,采用rep—PCR分子指纹技术对来自石屏县净种杂交稻田块、净种糯稻田块以及间种杂交稻糯稻田间的251个稻瘟病单孢分离菌株进行扩增．结果表明,所有供试菌株均分别扩增到9—17条DNA带,大小从400bp到23kb左右,但大多数带主要集中在5—10kb之间．所有菌株共扩增出的DNA指纹带中,约65％的为多态性DNA带,35％的为共同扩增带．将供试菌株扩增带诺进行聚类分析,比较间裁与净载田间病菌群体遗传结构的组成差异结果表明,在不同遗传相似水平,菌株遗传宗群复杂度与栽培方式有一定相关性。间栽田间病菌遗传宗群较净栽田问复杂,为3—5个,且优势宗群群不明显;而在净栽糯稻或净栽杂交稻田间遗传宗群较为简单,只有1—3个,且优势宗群明显．本试验结果证明水稻品种多样性有利于稻瘟病菌稳定化选择。     

一株拮抗稻瘟病菌细菌的筛选与鉴定

生防微生物是一种具有开发创新和环境友好的防控稻瘟病策略,旨在发掘高效生防微生物资源。于2014年从湖南桃江山区一季稻感病品种湘早籼24号的感稻瘟病稻丛的健康稻株中分离出817株菌株,采用平板对峙法,筛选出1株对稻瘟病菌具有高效抑制作用的拮抗细菌JN005,通过菌丝生长速率法测定其活体菌代谢产物对稻瘟病菌的抑菌率高达84%;并对另外5种植物病原真菌、4种植物病原细菌和大肠杆菌及金黄色葡萄球菌等11种菌作了抑菌谱测定。结果表明,JN005菌株对禾谷镰刀菌、水稻稻曲病菌有较好的抑制作用,其抑制率分别为70.1%和73.6%。通过形态学观察、生理生化测定及16S r DNA序列系统发育分析,将JN005菌株鉴定为枯草芽孢杆菌(Bacillus subtilis)。     

湖南桃江病圃稻瘟病菌的无毒基因及水稻抗瘟单基因联合抗性分析

【目的】鉴定湖南省桃江病圃稻瘟病菌无毒基因型,为合理搭配种植湖南省水稻抗瘟品种和抗病育种提供依据。【方法】在湖南桃江病圃采集水稻品种"丽江新团黑谷"(LTH)稻瘟菌病样,用单孢分离法分离稻瘟病菌单孢并纯化获得单孢菌株,用针刺离体法将菌株接种到以"LTH"为轮回亲本培育而成的24个含单抗瘟基因的水稻5叶期第5叶片上,对供试菌株进行无毒基因鉴定,并应用联合致病性系数和联合抗病性系数分析抗瘟基因组合间的互作。【结果】供试92个稻瘟病单孢菌株含有全部的24个无毒基因,对24个已知含单抗瘟基因的水稻材料表现出不同程度的毒力水平,含水稻抗瘟基因Pi-20对供试菌株抗菌频率最高,达54.35%;通过联合致病性系数和联合抗病性系数分析抗瘟基因组合间的互作,结果表明最佳搭配组合为Pi-20×Pi-k~s(RAC=0.28,PAC=0.23)。【结论】湖南省桃江病圃稻瘟病菌致病力较强,24个抗瘟基因多已感病化,含抗性基因Pi-20与Pi-k、Pi-k~s、Pi-3组合的水稻品种目前可在湖南省推广利用,但需研究引进新的抗瘟基因。     

增强UV-B辐射和接种稻瘟病菌对2个水稻品种幼苗叶片3个生理指标的影响

通过盆栽实验研究了单一增强UV-B辐射(2.5、5.0和7.5 kJ·m-2·d-1)以及增强UV-B辐射和稻瘟病菌(Magnaporthe grisea,菌株Y98-16T和Y99-63C)侵染复合胁迫对水稻(Oryza sativa L. )品种'黄壳糯'('Huangkenuo')和'合系41'('Hexi-41')幼苗叶片相对电导率、MDA含量和SOD活性3个生理指标的影响.结果表明:在低剂量(2.5和5.0 kJ·m-2·d-1)单一UV-B辐射条件下,2个水稻品种幼苗叶片的3个生理指标均较对照(自然光)有所降低;而在高剂量(7.5 kJ·m-2·d-1)单一UV-B辐射条件下,2个水稻品种幼苗叶片的3个生理指标均较对照有所增加.与对照(仅接种稻瘟病菌)相比,经低剂量(2.5和5.0 kJ·m-2·d-1) UV-B辐射后再接种稻瘟病菌,'黄壳糯'幼苗叶片的3个生理指标总体上均降低;而经高剂量(7.5 kJ·m-2·d-1)UV-B辐射后再接种稻瘟病菌,'黄壳糯'幼苗叶片的3个生理指标均有所增加.经不同剂量UV-B辐射后再接种稻瘟病菌,'合系41'幼苗叶片的3个生理指标总体上均有所增加,且2个水稻品种幼苗叶片的相对电导率与SOD活性均有显著的正相关性(P<0.05).与对照(仅接种稻瘟病菌)相比,接种稻瘟病菌后再经不同剂量UV-B辐射处理,'黄壳糯'幼苗叶片的3个生理指标均有所增加;而 '合系41'幼苗叶片的3个生理指标变化各异.接种稻瘟病菌菌株Y98-16T后再用UV-B辐射处理,2个水稻品种幼苗叶片的3个生理指标间均有显著或极显著的正相关性(P<0.05或P<0.01);而接种稻瘟病菌菌株Y99-63C后再用UV-B辐射处理,2个水稻品种幼苗叶片的3个生理指标间无明显的相关性.研究结果显示,在增强UV-B辐射和稻瘟病菌侵染复合胁迫条件下,因2个胁迫因子的作用顺序不同、稻瘟病菌菌株不同、UV-B辐射量不同以及水稻品种的差异,水稻幼苗叶片的细胞膜透性、MDA含量和SOD活性呈现出不同的变化趋势.     

云南30个水稻品种对水稻白叶枯病的抗性评价

【目的】水稻白叶枯病是一种严重危害水稻的细菌性病害,培育抗性品种是治理该病害的重要途径。因此,明确云南水稻材料对检疫性病害水稻白叶枯病的抗性,可以为该病害的防治与监测、水稻栽培的合理布局和良好抗性资源的获取提供依据。【方法】采用剪叶接种法测定云南稻区30个品种对7个不同致病型白叶枯病菌的抗性。【结果】在供试的30个云南水稻品种中,2个品种(玉粳16和JS42糯稻)对7个不同致病型菌株均表现为抗性;15个品种对7个致病型菌株均表现感病;对HEN11、SCYC-6、YN7、YN11、FUJ、YN241和PX099等7个致病型菌株表现抗性的水稻品种分别占26.67%、16.67%、23.33%、13.33%、6.67%、10.00%和20.00%。此外,区试材料的抗性比例高于主栽品种,地方稻未发现抗性品种。【结论】现在生产上的大部分水稻品种对优势致病型病原菌入侵的抵抗能力降低甚至丧失。针对云南地区的优势致病小种FUJ筛选得到2个抗性品种:玉粳16和JS42糯稻。     

白黄侧耳Pleurotus cornucopiae微卫星间区(ISSR)分析

本试验对我国1982年至2004年22年间栽培的白黄侧耳Pleurotus cornucopiae 30个菌株进行了锚定ISSR分析,试验表明,引物P4和P5都能对白黄侧耳P.cornucopiae进行多态性扩增,P4将供试菌株扩增出45个条带,大小在200～20000bp,P5将供试菌株扩增出39个条带,大小在500～15000bp,扩增出的条带100%具多态性。聚类分析在遗传相似性61%的水平下将30个供试菌株划分为15个类群,即15个具一定遗传差异的菌株;具有相同ISSR图谱、遗传相似性程度100%的可能为同一菌株,属于同物异名。试验表明我国的食用蕈菌野生环境面临人工栽培种质的污染,采自河北、山东、云南自然环境下的白黄侧耳P.cornucopiae与此前大量栽培的一些商业品种具完全相同的ISSR指纹图谱,聚类分析相似性系数100%。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.