利用回交法与Wx基因分子标记辅助选择培育糯性小麦

以中国春糯性位点全套近等基因系为研究材料,对小麦Wx基因的6个STS标记和1个CAPS标记进行了筛选。改良PCR扩增条件以及产物检测方式后,从这些标记中筛选出3个标记,包括鉴定Wx-A1、Wx-D1位点的2个共显性STS标记和Wx-B1位点的1个显性STS标记,用于本研究中糯性小麦的分子标记辅助育种。在育种过程中,首先配制全糯材料“98Y1441”与推广品种“川育12”的杂交组合,采用籽粒碘染法从其F2种子中选择全糯基因型个体与回交亲本川育12杂交,如此反复自交、回交,历经数代异地加代繁殖得到BC5F2代回交改良群体。利用上述3个分子标记从该群体中筛选出了8种Wx基因型,经卡方检验,其分离比符合3对基因的分离比例,其中基因型为aabbdd的植株有2株,直链淀粉含量分别为1.81%和0.82%,为全糯小麦;基因型为AAbbdd, aabbDD的部分糯性植株各有1株,直链淀粉含量分别为15.24%和17.57%。研究中获得的BC5 F2代群体的农艺性状接近回交亲本,并明显优于全糯材料“98Y1441”,表明采用回交法与Wx基因分子标记辅助选择相结合,有助于培育高产、优质的全糯和部分糯小麦。     

利用回交结合Wx基因分子标记培育部分糯性小麦

颗粒结合型淀粉合成酶Ⅰ(GBSSI,Waxy蛋白)是小麦胚乳中直链淀粉合成的关键酶。小麦基因组中存在3个Waxy基因(Wx-A1、Wx-B1、Wx-D1)。在白火麦中Wx-D1位点的突变(Wx-D1b)引起Wx-D蛋白的缺失,导致直链淀粉含量下降,其面粉表现出部分糯性。与目前生产上推广品种相比,白火麦的农艺性状较差,产量非常低。为了培育农艺性状优良的部分糯性小麦,我们将白火麦与具有优良农艺性状的小麦品种PH85-16、济南17和烟农15(轮回亲本)分别进行杂交,后代分别与相应的三个轮回亲本回交五代,在每代中均选择农艺性状与轮回亲本相近并含有Wx-D1b的后代。在第六代自交后选择具有Wx-D1b的纯合体,选出的单株连续自交三代。获得了六个农艺性状与轮回亲本相似的品系,它们均携带纯合的Wx-D1b位点。研究表明采用回交的方法并结合基于Wx基因序列的分子标记技术,是培育优良部分糯性小麦的一种非常有效的方法。本研究培育出的部分糯性小麦品系可以直接用于大田生产。     

黄淮冬麦区不同时期主推品种淀粉合成酶基因分子标记鉴定

利用普通小麦直链淀粉合成酶GBSS基因及支链淀粉关键合成酶SSⅡ基因的特异分子标记鉴定了黄淮冬麦区自20世纪50年代以来253份主推品种,发现8份品种缺失Wx-B1基因,其中5份材料（小偃168、秦麦1号、83S502、山东935031、山东928802）是新发现的缺失Wx-B1基因的小麦品种,未发现Wx-A1、Wx-D1基因缺失类型品种;所鉴定253份品种的SSⅡ基因均为野生型,未发现缺失突变类型。通过对8份缺失Wx—B1基因品种直链淀粉含量分析,发现这些品种的直链淀粉含量差异较大．变异范围为19．9％-33．0％,其中豫麦47、83S502和中育5号3个品种的直链淀粉含量较低,分别为19．9％、21．3％和26．4％,可以用于优质面条小麦品质改良。     

4个春性基因型小麦品种与‘京841’杂交F_1代的表型分析

选用4个具有不同显性春化基因型的小麦品种与冬性小麦品种‘京841’进行杂交实验,通过显性春化基因特异性PCR分析技术鉴定杂交F1代植株,并分析4个杂交组合的正反交F1代植株表型特性。结果显示,各显性春化基因已经导入到各杂交F1代植株中,且其苗穗期受显性春化基因的控制而有效缩短;3个杂交组合的F1代穗粒数在正反交之间存在显著差异,推测穗粒数受细胞质遗传因素的影响较大,其中以‘新春2号’和‘豫麦18’分别为母本和父本与‘京841’杂交后F1代的穗粒数表现出较强的杂种优势,4个杂交组合的F1代千粒重均表现出较强的杂种优势。     

转基因小麦外源优质亚基基因的杂交转育研究

在获得外源品质基因1Dx5和1Ax1超量表达的转基因小麦的基础上,利用小麦转基因品系‘B72-8-11b’和‘B102-1-2’为父本,主要以湖北省栽培品种‘鄂麦12’为母本,配置杂交组合。杂交后代中采用系谱选择法,结合HMW-GS鉴定,研究了转基因小麦外源品质基因在F1、F2、F3、F4代的传递,并筛选出外源1Dx5或1Ax1基因保持超表达的2个新型转基因株系;同时证明了将外源品质基因向栽培品种转育,是提高小麦优质亚基含量和提高HMW-GS总量的有效方法之一。     

中国糯小麦研究进展

由于糯小麦缺失(Wx-A1、Wx-B1和Wx-D1)3对蜡质基因,其直链淀粉含量低于1%,因此在食品工业和非食品工业中有着巨大的应用价值.自20世纪90年代以来,糯小麦研究已成为国际热点.虽然我国开展糯小麦研究起步较迟,但在糯小麦Wx基因资源的筛选、糯小麦的遗传和育种、糯小麦淀粉品质评价等方面取得了较快的进展.本文就中国在上述领域的研究进展作一综述,并就糯小麦研究提出几点建议.     

利用wx基因分子标记辅助选择培育糯性小麦

利用中国春及其缺体-四体对wx-B1基因的STS标记和wx-A1、wx-D1的微卫星(SSR)标记进行了定位.联合应用这2种分子标记,对12个小麦品种和5个高代糯麦株系做了鉴定,与Wx蛋白的SDS-PAGE结果一致;从组合江苏白火麦×关东107的F2分离群体中筛选出8种wx基因型,其中3种基因型(AD同缺型,BD同缺型和糯型)为自然界中所没有,并且培育出了国内首批糯性小麦品系.另外,应用SSR标记对江苏白火麦回交改良群体中个体进行辅助选择,得到了含wx-D1b的7D单体,为将来进一步改良糯性小麦的农艺性状提供广泛的遗传材料.利用wx基因分子标记辅助选择,可以加速培育糯性小麦的进程.     

白色种皮花生皮色及农艺性状遗传的研究

为育成白色种皮的高产花生品种,了解白色种皮的遗传规律,用自育的白皮1号品种与在福建省生产上推广的红皮良种粤油116、汕油对和泉花10号进行杂交,杂种F1植株的种皮全为红色．F2红皮植株与白皮植株的分离比例符合15:1的分离规律,红皮F2代的F3代株系中,有4/15株系符合红：白为3:1的分离比例。由此推断白皮性状是两对隐性基因控制,白皮性状与产量性状没有连锁。主要农艺性状的遗传力顺序为：单株结果数＞单株饱果重和生物产量＞单株饱果数。经F3代、F4和F5代的株系鉴定,选出稳定、综合性状优良的重组类型;再经过产量鉴定和多点比较试验,选出了丰产性较好的二个品种参加福建省花生新品种区域试验．     

杂交小麦品质改良技术体系的建立

利用生化标记辅助选择与温室加代回交育种相结合的方法,将优质高分子量谷蛋白亚基14＋15与5＋10的基因分别导入和聚合到高产杂交小麦‘西杂一号’亲本,用含有目标亚基的杂交小麦亲本组配杂交组合,获得含有单个优质亚基144-15、5＋10和聚合这两种优质亚基的‘西杂一号’,在保持原品种高产性状的同时提高了其HMW-GS组成品质评分,有望实现杂交小麦高产优质。     

SDS-PAGE分析转基因小麦与主栽小麦杂交后代的高分子量麦谷蛋白亚基

目的:高分子量麦谷蛋白亚基(HMW-GS)1Ax1、1Dx5是对小麦面包烘烤品质有重要影响的优质亚基。将转基因小麦株系与普通小麦栽培品种常规杂交并快速筛选后代,以选育含有外源优质亚基的主栽小麦品系。方法:将分别含有1Ax1、1Dx5亚基的转基因小麦株系B102-1-2、B73-6-1与3种普通小麦主栽品种鄂恩1号、鄂麦12号、日喀则8号常规杂交,用不连续SDS-PAGE方法鉴定12组杂交组合(正反交)F1代311颗籽粒的HMW-GS。结果:不连续SDS-PAGE分析大量子代带型,能够快速鉴定筛选出具有优质亚基的株系,转基因获得的外源优质HMW-GS基因在大部分F1子代中能够共显性遗传。结论:常规杂交育种能使外源基因有效地整合进主栽小麦的基因组中,进一步分析后代遗传的稳定性和遗传规律就可以培育出优质的新品种;不连续SDS-PAGE快速筛选优质亚基的株系具有可操作性和实用性。     

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.