Emergence of a new satellite RNA from cucumber mosaic virus isolate P1

The cucumber mosaic virus (CMV) isolate P1 caused very mild symptoms on many plant species After serial passages by mechanical inoculation over five years, CMV P1 caused severe symptoms on several tobacco cultivars and tomato. A specific band of approximately 0.3 kb in length was amplified by RT-PCR with primers synthesized based on reported CMV satellite RNA (satRNA) sequences. Sequence analysis showed there were two satRNAs (Sat-P1-1 and Sat-P1-2). Sat-P1-1 contained 335 nucleotides, and Sat-P1-2 contained 394 nucleotides. These two satRNAs shared 64% overall nucleotide sequence homology, and differences between the two satRNAs included mutations as well as deletions. Sat-P1-1 was identical to a satRNA (Z96099) reported in 1995 in CMV P1. Based on differences in the sequence and secondary structure between these two satRNAs, we conclude that Sat-P1-2 represents the emergence of a new satellite (necrotic satellite) from attenuated satRNA populations. The possible effect of the emergence of this new satRNA is discussed. Project supported by research grants from the Teaching and Research Award Program for Outstanding Teachers in Higher Education Institutes of the Ministry of Education of China and by the National Outstanding Youth Foundations of National Natural Science Foundation of China (No. 30125032). PhD student in Zhejiang University, from Agrarian University of Havana, Cuba.     

Characterization and RNA2 nucleotide sequence of broad bean wilt virus 2 isolate P158

Broad bean wilt virus 2 (BBWV2) isolate P158 was characterized and the complete nucleotide sequence of viral genomic RNA2 was determined. P158 has 30 nm diameter isometric particles. Double immunodiffusion test suggested that P158 has high antigenicity homology with BBWV2 isolate B935. SDS-PAGE result showed that the coat protein of P158 was comprised of two types of polypeptide with molecular weight of 44.7 kD and 21.9 kD, respectively. The genome of P158 was made up of two RNA molecules with the length of 6.0 kb and 3.6 kb, respectively. cDNA of RNA2 was cloned by RT-PCR and sequenced. RNA2 was composed of 3597 nucleotide (nt) residues excluding the poly(A) tail and contained single long open reading frame extending from nt 230 to nt 3424 in the viral sense RNA, and encoded a polyprotein ofMr 119002 (119K). Comparison of the polyprotein and the counterpart of isolate B935 indicated that the polyprotein was cleaved at Q/G (465/466) and Q/A (867/868), to release three mature proteins: a protein of unknown function, large and small subunit. Sequence comparisons of P158 with fabaviruses showed P158 had very high sequence homology with BBWV2 isolates and patchouli mild mosaic virus, but to a less extent with BBWV1 isolates. Project supported by NSFC (No 39770035; 39900005). The GenBank accession number of the sequence reported in this paper is AF228423.     

几种新型烟草花叶病毒抑制剂的田间药效试验

为对室内研究筛选出的具有抗烟草花叶病毒活性的几种抑制剂进行田间药效验证,采用高压喷枪接种烟草花叶病毒后每隔一周喷施制剂的方法对几种制剂进行了田间试验.试验结果显示,含1%3-丙酮基-3-羟基羟吲哚二甲基亚砜溶液1 000倍液、含0.4%苦木素的2%3-丙酮基-3-羟基羟吲哚微乳液500倍液两种制剂在接种烟草花叶病毒4周后仍然保持44.04%和47.71%的相对防效,防治效果明显优于对照药剂.     

CMV甜瓜分离物外壳蛋白基因的克隆及其生物信息学分析

从河南省临颖县采集的病毒感染的甜瓜样本经ELISA检测和接种分离获得黄瓜花叶病毒（Cucumber mosaic vi-rus,CMV）分离物。把该分离物接种于西葫芦,从发病的叶片中提取总RNA,并以此为模板经RT-PCR扩增获得CMV的外壳蛋白（cp）基因,将其克隆到pUCm-T质粒上。经序列测定和生物信息学分析,结果表明该cp基因由657个核苷酸组成,编码218个氨基酸。预测该蛋白的等电点为5。12,分子量约为24kD。其核苷酸序列与黄瓜花叶病毒亚组I的分离物有较高的同源性,达92.2%～93.9%,与亚组II的同源性仅为76.8%～77.8%,与我国报道的CMV分离物的cp基因序列比较,只有香蕉株系XB外核苷酸序列的同源性达91.8%～93.4%。根据这些分析,该CMV分离物属于亚组I。另外还对黄瓜花叶病毒外壳蛋白的高级结构作出了预测。     

A TOM1 homologue is required for multiplication of Tobacco mosaic virus in Nicotiana benthamiana

The AtTOM1 gene of Arabidopsis thaliana had been shown to be essential for the efficient multiplication of Tobacco mosaic virus(TMV) in A.thaliana.In this study,we cloned an AtTOM1-like gene from Nicotiana benthamiana named as NbTOM1.Sequence alignment showed that NbTOM1 is closely related to AtTOM1 homologues of N.tabacum and Lycopersicon esculentum with 97.2% and 92.6% nucleotide sequence identities,respectively.Silencing of NbTOM1 by a modified viral satellite DNA-based vector resulted in complete inhibition of the multiplication of TMV in N.benthamiana.The result suggests that inhibition of NbTOM1 via RNA silencing is a potentially useful method for generating TMV-resistant plants.     

草酸诱导甜瓜对南瓜花叶病毒的系统抗性的研究

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｓｑｕａｓｈｍｏｓａｉｃｖｉｒｕｓ (ＳｑＭＶ)ｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍ ｐｏｒｔａｎｔｃｕｃｕｒｂｉｔｖｉｒｕｓｅｓ[1～ 3] ,ａｎｄｉｔｃａｕｓｅｓｇｒｅａｔｌｏｓｓｅｓｉｎｍｕｓｋｍｅｌｏｎｐｒｏｄｕｃｔｉｏｎ[4 ] .Ｏｎｅｏｆｔｈｅｍａｉｎｗａｙｓｔｏｃｏｎｔｒｏｌｐｌａｎｔｖｉｒｕｓｄｉｓｅａｓｅｓｉｓｔｈｅｉｎｄｕｃｅｍｅｎｔｏｆｒｅｓｉｓ ｔａｎｃｅｔｏｖｉｒｕｓｅｓ[5] ｂｙｓｏｍｅｂｉｏｌｏｇｉｃａｌａｎｄｎｏｎ ｂｉｏｌｏｇｉｃａｌｆａｃｔｏｒｓ[6～ 9…     

黄瓜花叶病毒卫星RNA的研究进展

黄瓜花叶病毒卫星RNA是寄生于黄瓜花叶病毒粒子内的小分子核酸,卫星RNA必须依赖辅助病毒的复制而复制并反过来干扰CMV的复制,从而影响寄主的病状表现;CMV卫星RNA常被用于病毒病生物防治,也是研究小分子RNA与较高级病毒与寄主相互关系较合适的一种模式。近年来黄瓜花叶病毒卫星RNA的研究主要包括CMV卫星RNA对寄主症状的调节作用,卫星RNA的结构、遗传学性质、与辅助病毒互作的分子机制及其在基因工程中的应用。     

Microarray-based identification of tomato microRNAs and time course analysis of their response to Cucumber mosaic virus infection

A large number of plant microRNAs (miRNAs) are now documented in the miRBase, among which only 30 are for Solanum lycopersicum (tomato). Clearly, there is a far-reaching need to identify and profile the expression of miRNAs in this important crop under various physiological and pathological conditions. In this study, we used an in situ synthesized custom microarray of plant miRNAs to examine the expression and temporal presence of miRNAs in the leaves of tomato plants infected with Cucumber mosaic virus (CMV). Following computational sequence homology search and hairpin structure prediction, we identified three novel tomato miRNA precursor genes. Our results also show that, in accordance with the phenotype of the developing leaves, the tomato miRNAs are differentially expressed at different stages of plant development and that CMV infection can induce or suppress the expression of miRNAs as well as up-regulate some star miRNAs (miRNA*s) which are normally present at much lower levels. The results indicate that developmental anomalies elicited by virus infection may be caused by more complex biological processes.     

Science Letters： A TOM1 homologue is required for multiplication of Tobacco mosaic virus in Nicotiana benthamiana

The AtTOM1 gene ofArabidopsis thaliana had been shown to be essential for the efficient multiplication of Tobacco mosaic virus （TMV） in A. thaliana. In this study, we cloned an AtTOM1-like gene from Nicotiana benthamiana named as NbTOM1. Sequence alignment showed that NbTOM1 is closely related to AtTOM1 homologues of N. tabacum and Lycopersicon esculentum with 97.2% and 92.6% nucleotide sequence identities, respectively. Silencing of NbTOM1 by a modified viral satellite DNA-based vector resulted in complete inhibition of the multiplication of TMV in N. benthamiana. The result suggests that inhibition of NbTOM1 via RNA silencing is a potentially useful method for generating TMV-resistant plants.