中国17个优良玉米自交系的分子标记杂合性及其与杂交种性状的关系研究

在玉米单交种育种中 ,鉴定高产杂交种和具有优良特性的自交系是一个重要的问题。研究以 1 7个优良玉米自交系为亲本 ,按照双列杂交配组合 ,利用 RAPD技术分析了 1 7个自交系的多态性以及 RAPD标记与 9个重要农艺性状 (包括产量 )的关系。基于 RAPD标记计算的相似系数聚类将 1 7个自交系分为 5个类群 ,经分析与系谱亲缘关系基本一致。杂交种性状及其特殊配合力与亲本间的遗传距离是高度相关的 ,与聚类前比较 ,聚类后平均遗传距离与平均产量、平均特殊配合力的相关系数显著提高 ,类间平均产量高于类内平均产量。RAPD技术可揭示优良玉米自交系的系谱亲缘关系 ,将自交系划分成不同的类群 ,从而为选择类间自交系杂交 ,进行亲本选配和分子标记辅助育种提供一种方法。     

菜用和观赏甘薯种质资源遗传多样性分析

为了发掘菜用和观赏甘薯优异种质资源,通过对国家种质徐州甘薯试管苗库中1000余份资源材料进行鉴定,筛选了96份优异种质。利用30对SSR引物对入选材料进行了遗传多样性和群体结构分析,明确了这些材料遗传差异;并对入选材料12个表型质量性状进行主成分和聚类分析。结果表明:扩增的总条带数为275条,其中多态性条带为269条,多态率97.8%;利用DPS软件计算入选材料间的Nei72遗传距离为0.15~0.76,平均遗传距离0.66;群体结构分为3个组群,与分子标记聚类结果相似,表明入选材料有较大的遗传差异性;表型质量性状主成分分析得到5个主要成分,其累计贡献率达到80.50%;利用表型质量性状,可聚为8个组群。本研究通过分子标记与表型质量性状分析为下一步杂交选育菜用和观赏甘薯新品种提供了亲本选择信息。     

中国17个优良玉米自交系的分子标记杂合性及其与杂交种性状的 …

在玉米单交种育种中,鉴定高产杂交种和具有优良特性的自交系是一个重要的问题。研究以１７个优良玉米自交系为亲本,按照双列杂交配组合,利用ＲＡＰＤ技术分析１７个自交系的多态性以及ＲＡＰＤ标记与９个重要农艺性状（包括产量）的关系。基于ＲＡＰＤ标记计算的相似系数聚类将１７个自交系分为５个类群,经分析与系谱关系基本一致。杂交种性状及其特殊配合力与亲本间的遗传距离是高度相关的,与聚类前比较,聚类后平均遗传距离与     

基于遗传和表型特征的海岛棉遗传多样性分析

依据海岛棉种质资源的遗传及表型特征对其遗传多样性进行研究非常重要,可为海岛棉杂交育种选配亲本、引进新的种质资源拓宽优异基因范围以及培育海岛棉新品种提供理论根据。本研究通过利用125对SSR分子标记鉴定结果和13个农艺性状2年田间表型调查结果,对94份海岛棉种质资源进行遗传多样性分析,将这些材料按照遗传和表型特征进行类群的划分和比较,结果表明:(1)通过标记分析共检测到420个位点,其中249个为多态性位点,并应用Nei-Li相似系数法对94份材料间的遗传相似系数进行评估,发现94份海岛棉资源材料的遗传相似系数在0.46~0.95之间浮动,同时利用SSR分子标记将94份海岛棉资源材料划分为4大类群,分类结果与系谱分析基本吻合。(2)对94份海岛棉资源材料进行13个农艺性状及品质性状2年调查分析,发现供试材料品质性状的变异范围较广,而产量性状的变异范围相对较小。其中,各品种中马克隆值的多样性指数最高,最小的是单铃重。聚类分析发现,第Ⅰ类群产量性状的平均值较高;第Ⅱ类群虽在产量性状上不占优势,但其品质性状的表现较其他组别优异;第Ⅲ类群多为低产低质品种;第Ⅳ类群品种品质较优,产量变化范围较大。(3)利用SSR标记和农艺性状分析2种方法对94份海岛棉资源材料进行分析,结果均显示出较丰富的遗传多样性;2种方法的聚类结果基本一致,聚类结果与地理分布有明显的联系。     

水稻R7606、229A系列优异资源的创制

作物种质资源是品种改良的物质基础,随着分子生物学技术的发展,水稻育种已经发展到分子标记辅助选择与农艺性状选择相结合的高级育种阶段,种质资源的评价必须满足分子辅助选择育种的实际需要,进行分子辅助评价。本研究利用农业部《水稻品种鉴定DNA指纹方法》（NY/T1433-2007）推荐的24对 SSR引物,对32个水稻恢复系和13个水稻保持系资源材料进行DNA多态性分析,利用遗传相似系数及其主要农艺性状的差异选择亲本进行种质创新,在中间世代利用PCR-AccⅠ分子标记进对控制中等直链淀粉含量的基因型进行辅助选择,创制了系列新的优异资源。结果显示,32个水稻恢复系和13个水稻保持系资源材料的遗传相似系数变化范围分别为0.5244~0.8415、0.4783~1,平均遗传相似系数分别为0.6965、0.6542;选用其中的R3076、中恢8006、229和巨风A/B作为亲本,创制了恢复系R7606和细胞质雄性不育系229A系列资源,稻米品质检测结果表明,R7606系列资源有11个品系达到国标二级稻米标准;229A系列资源中则有3个品系达到国标一级,1个品系达到国标二级标准。经田间观察和配组试验,结果显示R7606及229A系列资源农艺性状优良,配合力较好,可以作为杂交水稻育种的优良亲本。本研究还对水稻遗传改良和种质创新过程中,如何利用对水稻优异资源的评价,拓展创新资源的遗传背景和遗传多样性,促进水稻育种和生产可持续发展进行了讨论。     

303份甘薯地方种SSR遗传多样性与群体结构分析

利用SSR分子标记,对我国303份甘薯地方种进行了遗传多样性和群体结构分析。进一步明确了甘薯地方种间的遗传多样性和亲缘关系,为优异资源挖掘和品种改良提供了参考。利用SSR建立研究材料的0~1数据库,通过NTSYS-pc2.10软件计算Nei72遗传距离矩阵,将遗传距离矩阵导入MEGA 6.06,计算平均遗传距离和聚类分析;并利用STRUCTURE2.3.4对303份地方种进行群体结构分析。结果表明:30对SSR引物共检测出203条多态性位点,每对引物检测到1~14条多态性条带,平均每对引物获得6.77条。303份材料的平均遗传距离为0.564,聚类分析在遗传距离为0.477处可以把303份材料分成11个类群,其中第Ⅺ类群在遗传距离为0.452处可分为3个亚群。群体结构分析将303份材料划分成了5个稳定的群体,群体结构划分与聚类有相似的结果,其中70份材料Q值小于0.6,属于混合亚群。     

甘蔗杂交品种核心种质重要农艺性状评价及亲缘关系分析

以107份甘蔗杂交品种核心种质为研究材料,ROC22为对照品种,通过新植和宿根2年的田间试验,对蔗茎公顷产量、甘蔗蔗糖分、公顷含糖量等性状进行最小显著差数法(LSD)两两比较和Duncan多重比较评价,筛选优异材料,利用SSR分子标记建立优异材料与我国骨干亲本的亲缘关系。结果表明36份材料在蔗茎公顷产量、甘蔗蔗糖分、公顷含糖量等指标上优于对照品种,可作为亲本进行杂交,且蔗茎公顷产量对公顷含糖量的影响远大于甘蔗蔗糖分对公顷含糖量的影响;20对SSR引物扩增得到292个标记,其中283个为多态性标记;优异材料与我国骨干亲本相似性系数范围在0.384~0.590之间,平均为0.437,存在较大的遗传差异;UPGMA聚类可将所有材料划分为5个类群,蔗茎公顷产量和公顷含糖量表现优异的材料在各类群都有分布,甘蔗蔗糖分表现优异的材料主要集中在Ⅱ、Ⅲ、Ⅳ类群,Ⅲ类群更集中;本研究为甘蔗种质创新、遗传育种提供了优异亲本材料,为杂交组合的配制提供重要指导。     

从农艺性状和分子标记鉴定一个水稻三倍体×二倍体F_2群体的遗传稳定性

一自然发生的三倍体水稻(OryzasativaL.)材料(SAR_3)与二倍体(生47)杂交,在F2代获得了一个稳定群体。群体形态表现、农艺性状分析和微卫星标记三个方面的研究表明:该杂交F2群体确系两个亲本的杂交后代,在杂交后有重组发生并迅速纯合,因而在形态上和遗传上呈现稳定性。对水稻中出现的这种早代稳定现象的利用途径和发生机制进行了探讨     

苹果属栽培种楸子的遗传多样性与遗传结构分析

利用荧光SSR分子标记,对新收集的苹果属栽培种楸子种质资源进行了遗传多样性和群体结构分析,明确群体内和群体间的遗传多样性和结构,为苹果属植物种质资源的收集保存和砧木育种亲本选择提供参考。利用荧光SSR构建研究材料的指纹数据,主要利用GenAlEx 6.501软件分析遗传多样性,利用POPULATION 1.2软件基于Nei遗传距离构建Neighbour-Joining(NJ)树,并利用STRUCTURE 2.3.4软件进行群体结构分析。结果表明:19对SSR引物共检测出390个多态性等位变异,平均多态性等位基因数为20.526,平均有效等位基因数为9.399,观察杂合度和期望杂合度的平均值分别为0.706和0.868,香农多样性指数为2.446,高于以往研究的苹果属植物的遗传多样性。基于Nei遗传距离的聚类分析,在遗传距离0.9167处155份材料可以分成3个类群,3个类群间的遗传距离较近,并没有完全按来源地划分为相应的类群。群体结构分析将155份材料划分成了2个稳定的群体,群体结构分组与NJ聚类有相似的结果,其中150份材料的Q值均大于0.6,血缘相对单一。     

甘蔗品种资源的表型遗传多样性

为了提高甘蔗品种资源的利用效率, 为甘蔗遗传育种亲本的选择、杂交组合配制及核心种质构建提供理论指导, 我们利用17个质量性状和5个数量性状分析了来自13个国家共20个地区的1,160份甘蔗品种资源的遗传变异、遗传结构和遗传距离等。结果表明: 5个数量性状在不同来源地品种群体之间的变异系数值(CV)变化较大, 说明不同来源地品种群体的数量遗传变异有较大差异, 其中来自海南的品种其群体遗传变异最丰富。质量性状的Shannon-Wiener多样性指数表明, 来自美国的品种群体遗传多样性最高, 其次为中国台湾, 第三为澳大利亚, 说明上述3个地区的甘蔗种质创新比较活跃, 在遗传育种中使用了更多表型性状多样化的亲本。不同来源地品种其群体的遗传分化系数(Gst)和基因流(Nm)显示甘蔗品种群体表型性状的遗传变异主要来自来源地内部, 且不同来源地品种群体之间存在较大的基因交流。遗传距离和UPGMA聚类分析结果表明, 各来源地品种群体之间遗传距离在0.0261–0.2945之间, 其中以福建和广东的品种最为相似, 其次为古巴和美国、广西和云南、澳大利亚和菲律宾、江西和四川、巴西和法国, 说明上述地区在杂交亲本的选择上比较相近。鉴于此, 在遗传育种中应加大利用具有丰富遗传多样性的品种材料并尽量避免选择同一组的品种相互杂交, 同时对于与其他来源地品种群体遗传距离较远的墨西哥品种群体在亲本选配时应给予更多关注。     

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.