Jacquot E, Hagen L S, Michler P, Rohfritsch O, Stussi-Garaud C, Keller M, Jacquemond M, Yot P
Institut de Biologie Moléculaire des Plantes, Université Louis Pasteur, Strasbourg, France.
Arch Virol. 1999;144(2):259-71. doi: 10.1007/s007050050502.
Cacao swollen shoot virus (CSSV) is a small non-enveloped bacilliform virus with a double-stranded DNA genome. A very restricted host range and difficulties in transmitting the virus, either mechanically or via its natural vector, have hindered the study of cacao swollen shoot disease. As an alternative to the particle-bombardment method previously reported, we investigated another approach to infect Theobroma cacao. A greater-than-unit length copy (1.2) of the CSSV DNA genome was cloned into the Agrobacterium binary vector pBin 19 and was transferred into young plants via Agrobacterium tumefaciens. Typical leaf symptoms and stem swelling were observed seven and eleven weeks post inoculation, respectively. Viral DNA, CSSV coat protein and virions were detected in leaves with symptoms. Agroinfected plants were used to study the in situ localization of CSSV and its histopathologic effects in planta. In both leaves and petioles, virions were only seen in the cytoplasm of phloem companion cells and of a few xylem parenchyma cells. Light microscopy showed that stem swelling results from a proliferation of the xylem, phloem and cortex cells.
可可肿枝病毒（CSSV）是一种小型无包膜的杆状病毒，具有双链DNA基因组。其宿主范围非常有限，且通过机械方式或经由其天然传播媒介传播该病毒存在困难，这阻碍了对可可肿枝病的研究。作为先前报道的粒子轰击法的替代方法，我们研究了另一种感染可可树的途径。将CSSV DNA基因组大于单位长度的拷贝（1.2）克隆到农杆菌双元载体pBin 19中，并通过根癌农杆菌转移到幼嫩植株中。接种后7周和11周分别观察到典型的叶片症状和茎肿胀。在出现症状的叶片中检测到病毒DNA、CSSV外壳蛋白和病毒粒子。利用农杆菌介导感染的植株研究CSSV在植物体内的原位定位及其组织病理学效应。在叶片和叶柄中，仅在韧皮部伴胞和少数木质部薄壁细胞的细胞质中观察到病毒粒子。光学显微镜检查显示，茎肿胀是由木质部、韧皮部和皮层细胞的增殖引起的。
