黄瓜花叶病毒2b蛋白对寄主光合速率和叶绿体结构的影响  

Effect of Cucumber Mosaic Virus-encoded 2b Protein on Photosynthesis and Chloroplast Structure of The Host Plant

作　　者：陈斐斐[1] 杜志游[1] 刘歆[1] 谢礼[2] 陈集双[1] 

机构地区：[1]浙江理工大学生物工程研究所,杭州310018 [2]浙江大学生命科学学院,杭州310029

出　　处：《生物化学与生物物理进展》2007年第8期889-896,共8页Progress In Biochemistry and Biophysics

基　　金：国家自然科学基金资助项目(30671361);科技部国际合作重点项目(2004DFA05000).~~

摘　　要：黄瓜花叶病毒(Cucumber mosaic virus,CMV)2b蛋白作为重要致病因子的角色在茄科模式植物上已为广泛描述,但其致病机理尚未廓清.从寄主叶绿体结构和光合特征的角度探索了病毒侵染过程中2b蛋白对心叶烟(Nicotiana glutinosa)的影响.首先利用PCR方法导入突变位点,构建了2b蛋白不表达的人工突变体Fny-CMV!2bpro,然后通过平行接种野生型Fny-CMV和Fny-CMV"2bpro,分析二者侵染后心叶烟的症状表现、叶绿素含量、光合速率以及叶绿体超微结构变化.结果显示:接种30天,Fny-CMV侵染的心叶烟表现重花叶、畸形和矮化症状,植株的光合速率和叶绿素含量显著降低,叶绿体形态和结构发生明显病变.但是,Fny-CMV#2bpro侵染的心叶烟植株仅表现轻微花叶或不表现明显症状,与健康对照相比,其光合速率和叶绿素含量没有显著差异,叶绿体形态和结构亦未出现明显病变.由此可见,野生型病毒侵染导致的相对低的光合速率和叶绿素含量,与2b蛋白引起的叶绿体形态和结构的破坏有一定的相关性.RNA杂交分析结果显示:2b蛋白的致病性与CMV子代RNA在寄主体内的积累量有关,不表达2b蛋白使得CMV基因组RNA1和RNA2含量显著下降,其亚基因组RNA4(编码CP蛋白)含量降低尤为显著.The 2b protein encoded by Cucumber mosaic virus （CMV） plays an important pathogenicity role in many solanaceous hosts, but mechanism of inducing disease is still unknown. In order to investigate virulence of the 2b protein on Nicotiana glutinosa plants, in terms of chloroplast structure and photosynthesis, a mutant Fny-CMVA2bpro, which cannot express the 2b protein, was achieved by introducing mutant sites in the 2b gene of Fny-CMV. N. glutinosa seedlings were inoculated with wild-type Fny-CMV and the mutant Fny-CMVA2bpro, and were analyzed for symptom expression, chlorophyll content, photosynthetic rate, and ultra-structural alteration of chloroplast. Up to 30 days post inoculation, wild-type Fny-CMV caused symptoms of severe mosaic, leaf deformation, and stunting, reduced photosynthetic rate and chlorophyll content, and altered the ultra-structure and morphological characters of the chloroplasts. However, host seedlings inoculated with the mutant Fny-CMV△2bpro expressed only slight mosaic symptom. Their photosynthetic rates and chlorophyll contents were not significantly different from those of the mock-inoculated plants, and the ultra-structure and morphological characters of their chloroplasts appeared to be normal. The observed low photosynthetic rates and chlorophyll contents were related to the breakage of the chloroplast morphology and ultra-structure. Results of Northern blotting showed that the virulence of 2b protein was associated with high accumulation level of CMV progeny RNAs in systemic leaves. Non-expression of the 2b protein reduced the accumulation levels of its genomic RNAs 1 and 2. The level of subgenomic RNA4, encoding CP protein, was found to be significantly decreased.

关 键 词：黄瓜花叶病毒 2b蛋白 光合速率 叶绿体结构 基因组含量 

分 类 号：Q78[生物学—分子生物学]