橡胶树三个品系（热研8-79、热研7-33-97和PR107）胶乳生理参数的比较研究

通过测定胶乳生理参数和胶乳产量,首次比较分析了橡胶树(Hevea brasiliensis)3个品系(热研7-33-97、热研8-79和PR107)的产排胶特性.结果表明,3个品系在初产期、未施乙烯利刺激时的胶乳产量和生理参数差异明显,胶乳产量为热研8-79>热研7-33-97>PR107;蔗糖转化酶活性与胶乳产量显著正相关,但其它生理参数与产量的相关性均不明显;割胶前一段时间的降水量是影响割次胶乳产量的重要因素,其中PR107品系受影响最大.这说明橡胶树品系的产排胶具有特异性,需要建立品系适宜性割胶制度.     

乙烯利诱导胶乳基因HbEtIe的克隆与表达分析

在成功构建巴西橡胶树(Hevea brasiliensis)胶乳差异表达cDNA消减文库的基础上,利用RACE技术成功克隆了一个新的乙烯利诱导表达胶乳基因HbEtIe。分析表明,该基因含有1个158 bp的内含子和2个长度分别为92 bp和178 bp的外显子;cDNA全长551 bp,包含1个270 bp的完整阅读框,174 bp的3′-UTR和107 bp的5′-UTR,推导氨基酸序列中含有一个未知功能结构域DUF581。HbEtIe基因在乙烯利刺激条件下的胶乳中特异性表达并受到乙烯利的调控,其表达量随处理时间的延长而增强。HbEtIe基因与拟南芥衰老相关基因SAG102具有较高的同源性暗示,HbEtIe可能参与了乙烯利诱导巴西橡胶树乳管衰老的分子调控。     

乙烯利刺激橡胶树增产及其分子生物学基础

本文介绍近年来乙烯利刺激橡胶树增产的分子生物学研究进展,讨论乙烯利刺激橡胶树胶乳增产的可能原因,并对这一领域今后研究的发展趋势进行了展望。     

巴西橡胶树橡胶生物合成关键基因REF,SRPP,HRT1和HRT2的表达分析

橡胶延长因子REF、小橡胶粒子蛋白SRPP、橡胶转移酶HRT1和HRT2是巴西橡胶树胶乳中的主要橡胶粒子蛋白,它们在橡胶生物合成中发挥重要作用,与橡胶树胶乳产量密切相关。为进一步探明REF、SRPP、HRT1和HRT2的基因表达与橡胶树胶乳产量之间的关系,以成龄未开割橡胶树无性系热研7-33-97胶乳为材料,通过实时荧光定量PCR的方法,对割胶伤害、外源乙烯利和茉莉酸刺激的处理条件下,橡胶树胶乳中的REF、SRPP、HRT1和HRT2的基因表达进行了分析。结果表明,随着割胶刀次的增加,REF基因在第4刀的表达量最高,而SRPP、HRT1和HRT2基因则在第6刀表达量达到最高;而在乙烯利和茉莉酸刺激处理下,REF、SRPP、HRT1和HRT2基因均在刺激8 h后表达量达到最高。因此,割胶(机械伤害)、外源乙烯利和茉莉酸刺激促进橡胶树产胶可能与它们提高橡胶生物合成相关橡胶粒子蛋白REF、SRPP、HRT1和HRT2的基因表达具有密切关系。     

巴西橡胶树液泡ATP酶F亚基基因克隆及表达

根据筛选文库时获得的EST序列信息,利用RACE技术分离了一个巴西橡胶树ATP酶 F亚基基因,命名为HbVHA-F.结果显示,该基因cDNA全长658 bp,含有完整的阅读框架,编码130个氨基酸.序列比对及结构预测分析表明,HbVHA-F编码的氨基酸序列与杨树、水稻、黄麻、小麦和香蕉中相应基因氨基酸序列的一致性分别达到88.46%、86.15%、84.62%、83.85%和74.62%,与杨树一致性最高,并与其他高等植物聚为一类.半定量RT-PCR分析显示,割胶(机械伤害)和乙烯利能够诱导HbVHA-F基因的表达.HbVHA-F基因可能通过转录表达调节参与了乙烯利刺激橡胶树增产的分子调控.     

巴西橡胶树HbMKK4基因的克隆及表达分析

采用RACE技术,从橡胶树‘热研7-33-97’中克隆了1个促分裂原活化蛋白激酶的激酶(MKK)基因HbMKK4。该基因全长cDNA序列1 580bp,编码框1 059bp,编码352个氨基酸,含有S_TKc结构域,其编码蛋白的分子量为38.83kD,理论等电点为9.36。实时荧光定量PCR结果显示,HbMKK4在橡胶树的根、树皮、胶乳及叶片中均有表达。割胶、茉莉酸甲酯和乙烯利均能上调胶乳中HbMKK4基因的表达,基因相对表达量分别在割胶后2h、茉莉酸甲酯处理8h和乙烯利处理4h后达到最高。研究结果推测HbMKK4可能通过MAPK信号途径参与茉莉酸信号途径的响应,可能在天然橡胶生物合成调控中起关键作用。     

使用微丝骨架解聚剂对橡胶树进行刺激采胶的研究

初步研究了不同浓度的(1%,5%,10%)KI、饱和浓度的大环内酯作为微丝骨架解聚剂对橡胶树的刺激排胶效果.2%的甲基纤维素处理的橡胶树作为空白.测定了各处理橡胶树的胶乳产量及胶乳的6种生理参数,即干胶含量、总固形物含量、蔗糖含量、无机磷含量、硫醇含量以及镁离子含量.结果表明施用1%KI和饱和浓度大环内酯的橡胶树胶乳产量大量增加,其增产幅度与作为天然橡胶常用刺激采胶剂--0.3%的乙烯利的增产幅度大致相当.比较通过1%KI和饱和浓度大环内酯刺激采胶的胶乳和0.3%的乙烯利刺激采胶的胶乳的各生理参数发现,3种处理得来的胶乳干胶含量和总固形物含量并没有明显的差别,但各处理的其它4个生理参数却差别明显,这意味着KI和饱和浓度大环内酯使橡胶树胶乳增产机制可能与乙烯利的机制不同.值得一提的是,高浓度的KI对橡胶树有明显的副作用,长时间的使用会引起橡胶树死皮病的发生.     

橡胶树DELLA蛋白编码基因HbGAI的克隆与表达分析

该研究采用RT-PCR与RACE技术,从橡胶树‘热研7-33-97’胶乳中克隆了1个DELLA蛋白编码基因HbGAI(GenBank登录号为KT696439)。HbGAI全长cDNA序列2 050bp,包含1个长1 842bp的完整开放阅读框。序列分析显示,HbGAI基因编码613个氨基酸,其推导的蛋白含有DELLA和GRAS结构域,分子量为66.476kD,理论等电点为5.19,无跨膜结构域,属于亲水性蛋白。进化树分析表明,HbGAI蛋白与其他植物中DELLA蛋白具有较高的相似性,与麻疯树JcGAI和蓖麻RcGAI亲缘关系较近。荧光定量PCR结果显示,割胶和茉莉酸甲酯处理下调胶乳中HbGAI基因的表达,乙烯利处理4h内显著上调胶乳中HbGAI基因的表达,表明HbGAI基因可能在橡胶树割胶、茉莉酸、乙烯响应中发挥作用。     

橡胶树胶乳4个HbRab基因的克隆和表达分析

克隆了橡胶树胶乳中表达的4个Rab基因的全长cDNA,命名为HbRab5-HbRab8。它们编码22～24kDa的蛋白,均具有小G蛋白家族共有的GTP／GDP结合保守结构域,分别属于植物Rab家族的F、D、A和B亚家族成员。组织表达分析显示,除HbRab69外,其他3个HbRab6基因均在胶乳中表达丰度最高。在胶乳中,伤害处理显著下调HbRab6表达而上调HbRab7表达：乙烯和水杨酸处理下调HbRab6和HbRab8的表达,甲基茉莉酸处理上调HbRab5、HbRab7、HbRab8的表达,细胞分裂素上调HbRab5的表达。本文结果为橡胶树胶乳再生相关Rab基因的筛选与功能阐述奠定了基础。     

橡胶树“死皮”及其防控策略探讨

天然橡胶是一种重要的工业原料,在2 000多种产胶植物中,巴西橡胶树(Hevea brasiliensisMuell.Arg.)以橡胶含量高、质量好、经济寿命长、易采收等独特优点成为天然橡胶的主要来源。作为典型的热带雨林乔木,全球适合橡胶树种植的土地资源极其有限,因而增加橡胶树的单位面积产量一直都是橡胶生产的核心任务。随着高产无性系的大力推广和乙烯利刺激割胶制度的广泛应用,橡胶单产目前已达到了前所未有的高度。然而,由于种种原因,橡胶树产排胶过程中会出现割线局部或全部不排胶的现象,即所谓的"死皮"。"死皮"给橡胶生产带来了巨大的损失(每年造成的干胶损失已超过15%),目前已成为制约橡胶树单产提高的主要因素。由于"死皮"成因的复杂性,至今对"死皮"的发生发展规律知之甚少。结合生产实践,讨论了不同"死皮"类型的主要特征和发生规律,并针对不同"死皮"类型、严重程度提出了一些切实可行的防控策略。     

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.     

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     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various