Identification of two commercial tomato cultivars as new indicator plants for detecting Citrus exocortis viroid infection

。以商用番茄品種作為偵測柑橘鱗砧類病毒（CEVd）之替代性指示植物

林雋軼(Chun-Yi Lin) ； 吳孟玲(Meng-Ling Wu) ； 洪挺軒(Ting-Hsuan Hung)

《植物病理學會刊》 24卷1期 (2015/03) Pp. 1-11

https://doi.org/10.6649/PPB.201503_24(1).0001

摘要

柑橘鱗砧類病毒（Citrus exocortis viroid, CEVd）感染三分之一的台灣柑橘植株，已成為柑橘產業中潛在威脅之病害。使用指示植物來偵測類病毒至今仍是可信度與專一性皆高的生物檢定法。栽種容易且具備完整基因體資訊的番茄是偵測鱗砧類病毒之合適的指示植物。然而，長期以來使用為CEVd指示植物的番茄品種'Rutgers'並非是常見的商用品種，且取得不易。在台灣僅可向亞洲蔬菜研究發展中心購買，且價格昂貴。本研究著重於從29種台灣常見商用番茄品種中挑選出具潛力的替代性指示植物。經由初步感染試驗的結果可顯示當中的24種商用品種皆會被鱗砧類病毒所感染。在三種不同溫度環境下，使用來自台灣東、西部的兩代表性鱗砧類病毒品系之人工感染性選殖株進行人工感染後，僅兩種番茄品種（'HV-206'及'V-191'）會產生嚴重的矮化及葉部病徵。根據病徵嚴重程度差異，品種'HV-206'對西部鱗砧類病毒品系較為感病，而品種'V-191'則對東部類病毒品系更為感病。此外，根據定量RT-PCR分析顯示，感染六周後的番茄中，不論在低溫或高溫環境下，鱗砧類病毒在品種'V-191'中的複製量高於品種'HV-206'。本研究結果顯示，單一類病毒品系會與不同寄主進行交互作用而呈現不同程度的病原性；而溫度雖能加速病徵發展的進程，但在類病毒的感染上並非是關鍵的影響因子。由連續六周的類病毒含量曲線也可證實兩類病毒品系在分別感染同一番茄品種時具有相似的成長曲線，且溫度並不會影響類病毒的增殖及含量。

關鍵字

柑橘鱗砧類病毒 ； 指示植物 ； 人工感染性選殖株 ； 番茄

並列摘要

Citrus exocortis viroid (CEVd) infects nearly one third of the citrus plants in Taiwan, thereby becoming an increasing threat to the citrus industry. Using indicator plants to detect CEVd infection remains a reliable and specific bioassay method. Tomato (Solanum lycopersicum L.) is an ideal indicator plant for CEVd because it grows easily, develops fast and distinctly visible CEVd symptoms and has a well-characterized genome. However, the commonly used indicator cultivar Rutgers is not readily available and its seeds are very expensive and can only be obtained from the Asian Vegetable Research and Development Center (AVRDC), The World Vegetable Center in Taiwan. This study focused on finding new alternative indicator tomato plants from 29 commercial cultivars in Taiwan. Our reverse transcription (RT)-PCR results showed that 24 of the 29 cultivars could be infected. We selected two ('HV-206' and 'V-191') from these 24 for in depth analyses. Both cultivars exhibited obvious stunting and severe foliage symptoms when infected by two CEVd isolates from western (Yunlin isolate) and eastern (Hualien isolate) regions under three temperature regimes. Based on symptom severity, 'HV-206' was more susceptible to the Yunlin isolate and 'V-191' was more susceptible to the Hualien isolate. RT-PCR showed that CEVd replicated at higher levels in 'V-191' than in 'HV-206' at low and high temperatures. Although temperature was not a key factor in viroid titer for a given cultivar, higher temperatures accelerated symptom development. Based on our findings, we recommend 'HV-206' and 'V- 191' for use as alternative indicator plants in CEVd detection.

並列關鍵字

Citrus exocortis viroid ； indicator plant ； infectious clone ； tomato