台灣農作物重要植物菌質體病害研究現況

Abstract

植物菌質體 (phytoplasma) 是一種無細胞壁的原核生物，也是重要的植物病原菌，可造成 500種以上的植物病害。它至今仍無法以人工的培養基進行培養，不易進行研究。植物菌質體引起的植物病徵常與植物病毒病害類似，因此被歸類於似病毒病害 (virus-like disease)，主要可藉由無性繁殖 (vegetative propagation)與媒介昆蟲如葉蟬(leafhopper)、飛蝨 (planthopper) 及木蝨(psyllid)等來傳播。台灣對植物菌質體病害的研究主要著重在診斷鑑定、傳播生態與病菌基因體等方面，近來也擴展至致病機制的探討。目前台灣較重要的植物菌質體病害包括梨衰弱病、木瓜衰弱病、花生簇葉病、絲瓜簇葉病、甘藷簇葉病、泡桐簇葉病及日日春葉片黃化病等，過去水稻黃萎病與甘蔗白葉病也曾嚴重發生。近年來又陸續在柑橘、馬鈴薯、葡萄與蓮霧發現疑似新的植物菌質體病害，但其致病能力仍在持續研究中。 Phytoplasmas are prokaryotic organisms that have no cell walls.They are important plant pathogens causing more than 500 plant diseases.The pathological studies of phytoplasmas are hampered because they have not yet been successfully cultured in vitro so far. They were categorized as the “virus-like diseases” based on the fact that the symptoms they induced were usually similar to those induced by plant viruses. Phytoplasmas are mainly transmitted through vegetative propagations and by insect vectors such as leafhoppers, planthoppers and psyllids. The researches on phytoplasma-caused diseases in Taiwan were focused on their diagnoses, ecology and genomics. The investigation of pathogenesis of phytoplasma diseases was recently initiated. Currently important phytoplasma diseases occurring in Taiwan include pear decline, papaya dieback, peanut witches’-broom, loofah witches’-broom, sweet potato witches’-broom and periwinkle leaf yellowing. Rice yellow dwarf and sugarcane white leaf were severe diseases years ago. Recently, several disorders similar to phytoplasma- associated cases were discovered in citrus, potato, grape and wax apple plants, but the confirmation of their pathogeneses on their respective hosts are under investigation.