玉米粗缩病毒基因组第七组份的cDNA克隆及序列分析

从采自中国河北滦城感病的玉米材料中提取玉米粗缩病毒(MRDV)的双链RNA。根据已知MRDV的部分序列设计引物，反转录、PCR扩增，克隆并测序分析了MRDV的第七片段(S7)cDNA序列。结果表明，S7 cDNA序列全长为1936bp，与国外所测的MRDV S7的序列长度相等，而且S7包含的两个阅读框(ORF1和ORF2)位置无变化。它们的核苷酸和最大开放阅读框(ORF1)同源性分别为877%和91.6%，然而，MRDV S7的片段与水稻黑条矮缩病毒(RBSDV)S8片段的核苷酸和最大开放阅读框(ORF1)有更高的同源性，分别为95.5%和93.5%。

cDNA CLONING AND SEQUENCE ANALYSIS OF THE SEVENTH SEGMENT OF MAIZE ROUGH DWARF VIRUS GENOME

The double strand RNA of maize rough dwarf virus (MRDV)was prepared from the maize samples showing symptoms which was from the Luanchen county of Heibei province of China. The primers were designed according to the known sequence of MRDV, the cDNA sequence of the seventh segment of MRDV was obtained by RT PCR, the S 7 sequence was analyzed by computer after sequencing. The results showed: the full length of the S 7 cDNA is 1936bp and equal to that of the S 7 cDNA from abroad, the two open reading frame(ORF1 and ORF2)contained in the S 7 segment are also unchanged. In comparison with the S 7 segment from Italy, the homolygy of S 7 nucleotide is 87 7% and the homology of ORF1 amino acid sequence is 91 6%. However, the MRDV S 7 segment and the rice black strike dwarf virus S 8 segment showed 95 5% nucleotide identities and 93 5% ORF1 amino acid identities.