Phytoplasmas of Two 16S rDNA Groups Are Associated with Pear Decline in Taiwan

造成台灣地區梨樹衰弱病之二群植物菌質體之研究

劉淑玲(Shu-Ling Liu) ； 劉秀玲(Hsiu-Lin Liu) ； 張淑貞(Shu-Chen Chang) ； 林長平(Chan-Pin Lin)

《Botanical Studies》 52卷3期 (2011/07) Pp. 313-320

摘要

本研究利用聚合酵素連鎖反應之檢測策略(Polymerase chain reaction (PCR)-based detection strategies)進行台灣梨樹衰弱病(pear decline in Taiwan, PDTW)之流行病學研究及媒介昆蟲之研究。本研究成功利用PCR由感染梨衰弱病之橫山梨(Pyrus serotina Rehd. cv. Hengshan)植株及媒介昆蟲中國梨木蝨(Cacopsylla chinensis)全DNA中增幅出兩種PCR產物，經由選殖定序及比對分析，顯示其分別屬於group 16SrX之台灣梨衰弱病(PDTW)植物菌質體與另一屬於group 16SrII之pear decline phytoplasma(PDTWII)之16S rDNA序列。由罹病梨樹所增幅出之PDTW及PDTWII植物菌質體之16S rDNA序列，分別與由中國梨木蝨(C. chinensis)上增幅出之兩種植物菌質體序列相同。藉由中國梨木蝨咬食傳菌試驗，證實PDTW以及PDTWII植物菌質體皆能由中國梨木蝨傳播到梨株。17株試驗梨樹中，有一株同時感染PDTW及PDTWII植物菌質體，另有十株感染PDTWII植物菌質體。嫁接傳菌試驗亦由田間罹病梨株枝條嫁接PDTW以及PDTWII植物菌質體至日日春(Catharanthus roseus)。根據上述PDTW與PDTWII菌質體之rRNA基因序列，分別設計出PDTW菌質體及PDTWII菌質體之專一性引子對，作為後續田間病害檢測及可能媒介昆蟲生態調查之工具。針對罹病梨葉、黔梨木蝨(C. qianli)及中國梨木蝨進行TEM切片觀察，分別於植物篩管、韌皮部薄壁細胞以及蟲體腸壁組織中，皆觀察到植物菌質體。

關鍵字

嫁接 ； 昆蟲咬食傳菌試驗 ； 植物菌質體偵測 ； 穿透式電子顯微鏡 ； 媒介昆蟲

並列摘要

Polymerase chain reaction (PCR)-based detection strategies were adopted to examine the etiology and vectorship of pear decline in Taiwan (PDTW). 16S rDNA sequences were amplified from total DNAs prepared from PDTW-affected pear trees Pyrus serotina Rehd. cv. Hengshan and pear psyllid Cacopsylla chinensis using PCR. According to the sequence analyses, C. chinensis carried phytoplasmas of two 16S rDNA groups, PDTW (group 16SrX) and PDTWII (a newly discovered group 16SrII phytoplasma associated with pear decline in Taiwan), that were associated with PDTW-infected pear trees. The 16S rDNA sequences of PDTW and PDTWII phytoplasmas that were amplified from diseased pear trees were identical to those from C. chinensis. Transmission trials of phytoplasmas associated with PDTW to healthy pear plants were successfully performed with C. chinensis. One of the 17 tested plants was infected with both PDTW and PDTWII phytoplasmas while ten were infected with PDTWII phytoplasma. In grafting tests, both PDTW and PDTWII phytoplasmas were effectively and separately transmitted from diseased pear to periwinkle plants (Catharanthus roseus). For detection purposes, specific primers were developed and adopted to detect both PDTW and PDTWII phytoplasmas by nested or semi-nested PCR. Transmission electron microscopic examinations revealed phytoplasma bodies in the sieve tubes and phloem parenchyma cells of diseased pears and in the intestinal wall cells of C. chinensis and C. qianli.

並列關鍵字

Grafting ； Insect transmission ； Phytoplasma detection ； Transmission electron microscope ； Vectors