陆地棉超矮杆突变体基因的初步定位

陆地棉超矮杆是一种新发现的突变体材料。前期对其遗传规律的研究表明,超矮杆突变性状是受一对完全隐性基因du控制的质量性状。文章以"超矮1号"和"新陆早16"配置的F2为作图群体,通过对双亲以及近等基因池的筛选,在1 350对SSR引物中共获得70对多态性引物。而后检测F2作图群体每个单株的基因型,显示有36个标记可以连锁,分布在8个连锁群上,其中超矮杆突变性状位于连锁群LG01。与目标基因du连锁的分子标记有7个:NAU2679、NAU2749、NAU905、NAU2838、NAU5373、NAU2238和NAU4946,它们皆为共显性标记。依据现有的棉花遗传图谱,标记NAU4946、NAU2238、NAU905、NAU5373和NAU2679位于第6染色体上,而目标基因du位于NAU2238和NAU4946之间,遗传距离分别为3.3 cM和1.4 cM,由此推定du在第6条染色体上。     

黄瓜SRAP遗传连锁图的构建及侧枝基因定位

在由黄瓜的两个自交系S06与S52杂交产生的F₂群体中, 应用SRAP(sequence-related amplified polymorphism)标记构建遗传连锁图谱, 检测控制黄瓜侧枝数(lbn)和侧枝平均长度(lbl)的数量性状座位(QTL). 使用筛选出的64个多态性引物组合对F2群体进行分析, 得到108个多态性位点. 经MAPMAKER/EXP3.0分析(LOD≥3.0), 获得由92个标记座位组成、覆盖7个连锁群的遗传图谱, 总长1164.2 cM, 标记平均间距12.6 cM. 应用QTLMapper1.6, 各检测到4个控制lbn和lbl的QTL, 其中, 对lbn贡献率最大的QTL位于第二连锁群的ME11SA4B-ME5EM5区间, 其S06基因型具有增效作用; 对lbl贡献率最大的QTL位于第二连锁群的DC1OD3-DC1EM14区间, 其S06基因型具有增效作用.     

玉米抗南方锈病基因的QTL定位

为发掘新的抗南方锈病基因资源,本研究以感病自交系黄早四为母本、抗病自交系W456为父本,构建F2群体并开展抗病基因定位研究。采用人工接种鉴定的方法对两个亲本、F1、F2群体及对照材料进行表型鉴定和遗传分析。利用均匀覆盖10条染色体的200个SSR标记,分析240个F2单株的基因型并构建含有200个SSR位点的遗传连锁图,连锁图总长度3331 cM,标记间平均距离16.6 cM。使用QTL IciMapping V4.1软件中的完备区间作图法对抗病QTL进行分析,共检测到6个控制南方锈病的QTL:qSCR3、qSCR7、qSCR8-1、qSCR8-2、qSCR9和qSCR10,邻近标记分别为umc2105和umc1729、umc1066和bnlg2271、umc1904和umc1984、umc1984和bnlg1651、umc1957和bnlg1401、umc2034和umc1291,分别位于3、7、8、9和10号染色体上,其中8号染色体上有两个位点,标记区间长度在5～19 cM之间。单个QTL的表型贡献率在2.61%～24.19%之间,可以解释表型总变异的62.3%,其中3个QTL贡献率大于10%,位于10号染色体上的qSCR10贡献率最大,可解释表型变异的24.19%。通过对目标区间标记加密,将该位点的定位区间进一步缩小到2.51 cM内,与两侧标记的距离分别是2.15 cM和0.36 cM。初步定位得到10号染色体上存在抗南方锈病的主效QTL,可为抗病品种的培育提供参考。     

水稻紫色柱头的遗传分析与基因定位

rdh是四川农业大学水稻研究所通过组织培养和连续自交得到的一个具有红色籽粒和紫色柱头,遗传上稳定的籼稻材料。抽穗期在rdh与3个无色柱头品种蜀恢527、蜀恢368和蜀恢168之间分别做正反交,结果显示F1群体在柱头颜色上正反交之间没有明显区别,全部是紫色的。F2群体发生分离成为两组,一组具有紫色柱头,另一组具有无色柱头。每一个F2群体的紫色柱头对无色柱头均适合3：1的比例,表明rdh紫色柱头性状的遗传是由一对显性核基因控制的。组合rdh／蜀恢527 F2分离群体中40个具有紫色柱头的显性单株和284个具有无色柱头的隐性单株构成定位群体。从两个亲本rdh和蜀恢527提取的基因组DNA,用涵盖水稻整个基因组的252对微卫星标记作引物扩增片段。结果发现有78对微卫星标记在两亲本之间具有多态性。然后用这78对标记作引物,扩增亲本、F1、F2显性单株和F2隐性单株、,结果显示位于水稻第6染色体的RM276、RM253以及RM111与rdh紫色柱头基因有连锁关系。再用RM276、RM253以及RM111作引物扩增剩余的全部具有无色柱头的隐性单株。结果表明：在RM276的扩增产物中,有20个单交换和2个双交换;在RM253中有2个单交换：在RM111中有3个单交换。因此,rdh紫色柱头基因被定位于水稻第6染色体。根据公式P=（h＋2b）／2n,计算得到微卫星标记RM276,RM253和RM111与rdh紫色柱头基因的遗传距离分别是4．2cM、0．35cM以及0．53cM。根据已经发表的RM276、RM253和RM111在第6染色体上的位置以及计算得到的rdh与RM276、RM253和RM111之间的遗传距离,构建了部分连锁图谱,并暂时将这个紫色柱头基因命名为Ps-4。     

玉米P25自交系抗锈病基因的遗传分析及SSR分子标记定位

以玉米南方型锈病免疫自交系P2 5和感病自交系F3 4 9及F1、F2 、B1和B2 为材料 ,采用主基因 多基因混合遗传模型研究了P2 5的抗病遗传规律。结果表明 :自交系P2 5的抗病基因为一主基因 ,表现为加性效应 ,没有检测出多基因 ,其在F2 、B1和B2 群体的遗传率分别为 81 88%、38 14 %和 5 5 1%。利用SSR分子标记技术 ,以组合P2 5×F3 4 9的F2 :3 家系作为构图群体 ,构建了玉米SSR遗传连锁图谱 ,并将玉米抗南方型锈病基因定位于 10号染色体上 ,与phi0 5 9标记的遗传距离为 5 8cM。     

用微卫星标记定位太空诱变玉米核不育基因

用姊妹交多代的太空诱变玉米雄性不育材料RP3195(A)×S37(自交系)的两个不同果穗的F2代群体作为育性调查和基因定位群体,这两个果穗的F2代群体分别为138株和247株。用326对微卫星引物进行差异筛选,其中有56对引物出现多态性,然后用56对引物对F2代群体进行分析,结果表明引物bnlg197和umc1012与不育基因连锁,其中在F2代群体的不同果穗中引物bnlg197与不育基因之间的遗传距离分别为7cM和14.5cM,标记umc1012在F2代群体(138株)中与不育基因之间的遗传距离为28.5cM,据此将该核不育基因定位在3L染色体上。     

一个玉米矮秆突变体K123d的遗传鉴定

矮秆已被广泛用于改良作物的抗倒伏性状,培育理想株型,从而提高作物产量。玉米矮秆突变体K123d由自交系K123自然突变产生。本研究比较该突变体与野生型主要农艺性状差异及其对赤霉素的敏感性;用K123d与株高不同的3个自交系分别构建F1、BC和F2群体,分析矮秆性状的遗传模式;以K169/K123d-F2为定位群体,采用集团分离分析法(BSA),运用SSR标记定位矮秆基因d123;参照br-2序列信息分段设计特异引物,同源克隆d123。结果表明,与野生型相比K123d株高降低35.59%,穗位高降低、节间缩短、叶片较直立,但结实率差,对赤霉素敏感;在F2群体和BC1群体中,正常植株与矮秆植株分离比例分别符合3∶1和1∶1,说明矮秆性状受1对隐性基因控制;其矮秆基因d123定位于第一条染色体上SSR标记umc1278和bnlg1564之间,遗传距离分别为12.8 c M和7.3 c M;同源克隆显示d123与br-2存在12个碱基替换,其中第4个外显子编码的一个谷氨酸被替换为赖氨酸。由此可见,矮秆突变体K123d为br-2的一个突变类型,对矮化育种具有进一步研究利用价值。     

陆地棉皱缩叶突变体基因wr3的初步定位

陆地棉皱缩叶突变体是本项目组自主发现的一种自然突变体。前期对其表型性状的观察发现该突变体的农艺性状有别于前人已报道的皱叶突变体;通过陆陆杂交世代群体对其遗传规律的研究表明, 皱缩叶突变性状是受一对完全隐性基因wr3控制的质量性状。文章以皱叶突变自交系L037和海7124为亲本配置组合得到的海陆杂交F2为作图群体, 利用本实验室遴选的平均覆盖棉花26对染色体上的234对SSR引物(每染色体相对等距离分布9对引物), 通过对双亲以及近等基因池的筛选, 共得到12对多态性引物。用这些引物检测F2作图群体每个单株的标记基因型, 经Join Map 4.0分析显示, 位于Chr.21的引物BNL3279与目的基因连锁, 二者间的遗传距离为28.7 cM。随后对Chr.21上的其他引物进一步筛选, 共得到16对与目的基因连锁的标记, 其中与目的基因距离最近的标记NAU3740的遗传距离为4.8 cM, 另一侧标记cgr5428的遗传距离为10.4 cM。由此推定, 皱缩叶突变体基因wr3在棉花第21染色体上。     

大白菜抽薹性状的主基因＋多基因遗传分析

以大白菜易抽薹自交系06S1703和耐抽薹自交系06J32形成的P1、P2、F1、F2、B1和B2等6个世代为材料,应用主基因+多基因多世代联合分析方法,对大白菜抽薹性状进行了研究.结果表明,大白菜的抽薹性受2对加性-显性-上位性主基因+加性-显性-上位性多基因控制,其中2对主基因的加性效应值分别为-3.575 8和-13.619,显性效应值分别为-3.755 2和-2.257 7.B1、B2和F2世代的主基因遗传率分别为87.95%、95.13%和96.25%,只在B1群体中检测到多基因效应,遗传率仅为1.39%,说明大白菜的抽薹性是以主基因遗传为主,可以进行早期选择.     

黄瓜白色果皮基因遗传规律及定位研究

以黄瓜嫩果深绿色果皮自交系1507(P1)和白色果皮自交系1508(P2)为亲本,构建6世代遗传群体(P1、P2、F1、F2、BC1P1、BC1P2),对黄瓜嫩果白色果皮基因(w)进行遗传规律分析和基因定位研究。结果表明,黄瓜白色果皮性状由隐性单基因(w)控制,深绿色对白色为显性。利用F2群体,结合分离群体分组分析法筛选得到了14个与w基因相关的SSR标记,构建了该基因的SSR连锁群,将其定位到黄瓜3号染色体上,两侧的标记为SSR23517和SSR23141,遗传距离分别为4.9cM和1.9cM。侧翼标记之间的物理距离为1 150kb,在该区域中共预测了500个候选基因。该研究对w基因的初步定位,为该基因精细定位及分子标记辅助选择育种奠定了良好的基础。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.