Abstract

Tomato spotted wilt virus (TSWV) infecting chrysanthemum (Dendranthema grandiflora L.) has been identified as a major constraint for chrysanthemum cut-flower industries in Southern India. The disease symptoms include veinal necrosis, necrotic spots on leaves, deformed flowers, and stem necrosis. The presence of TSWV in chrysanthemum plants collected from farms at Kotagiri, Nedugula, and Yercaud in Tamil Nadu State, India, was confirmed by the triple antibody sandwich-enzyme-linked immunosorbent assay (TAS-ELISA). The pathogenicity of TSWV was established for three isolates (TN1KO, TN2NE, and TN3YE) by mechanical inoculation of sap into chrysanthemum cuttings. Host range experiments in different host plants indicated that the isolates expressed symptoms typical of TSWV in all hosts assayed. Furthermore, Nicotiana tabacum L. had maximum virus titre among the tested host plants, and therefore was identified as the best indicator and the propagative host. The nucleocapsid (N) gene of the three studied isolates shared 99.2–100% identity at the amino acid level among themselves and 96.5–99.6% identity with reference TSWV isolates. The non-structural movement protein (NSm) gene of studied isolates shared 99.0% identity among themselves and 96.0%–100% identity at the amino acid level with reference TSWV isolates. The phylogenetic relationship analyzed based on the amino acid sequence identity of the N gene revealed that the studied isolate clustered as a single group with all the TSWV isolates taken for comparison. However, analysis based on the NSm gene indicated that the Indian isolates grouped with isolates from South Korea, the USA, Italy, Spain, and Australia.

摘要

感染菊花 ( Dendranthema grandiflora L.) 的番茄斑萎病毒 (TSWV)已被确定为印度南部菊花切花产业的主要制约因素。病害表现为叶脉坏死、叶片坏死斑、花畸形、茎坏死等。从印度泰米尔纳德邦 Kotagiri、Nedugula 和 Yercaud 的农场收集的菊花植物中存在 TSWV，通过三抗体夹心酶联免疫吸附测定 (TAS-ELISA) 证实。通过将汁液机械接种到菊花插条中，确定了三种分离株（TN1KO、TN2NE 和 TN3YE）对 TSWV 的致病性。在不同寄主植物中的寄主范围实验表明，分离株在所有检测的寄主中都表现出典型的 TSWV 症状。此外，烟草L. 在受试宿主植物中具有最大病毒滴度，因此被确定为最佳指标和繁殖宿主。三个研究分离株的核衣壳 (N) 基因在氨基酸水平上具有 99.2-100% 的同一性，与参考 TSWV 分离株的同一性为 96.5-99.6%。所研究分离株的非结构运动蛋白 (NSm) 基因与参考 TSWV 分离株在氨基酸水平上具有 99.0% 的同一性和 96.0%–100% 的同一性。基于 N 基因的氨基酸序列同一性分析的系统发育关系表明，所研究的分离株聚集为一个组，所有 TSWV 分离株都用于比较。然而，基于 NSm 基因的分析表明，印度分离株与来自韩国、美国、意大利、西班牙和澳大利亚的分离株分组。