Histopathology and Bacterial Populations of Atypical Symptoms-Inducing Xanthomonas axonopodis pv. citri Strains in Leaves of Grapefruit and Mexican Lime

引起非典型病徵之柑橘潰瘍病菌Xanthomonas axonopodis pv. citri菌株在葡萄柚及墨西哥萊姆葉片上之組織病理學及菌量變化

林信成(Hsin-Cheng Lin) ； 徐世典(Shih-Tien Hsu) ； 曾國欽(Kuo-Ching Tzeng)

《植物病理學會刊》 18卷3期 (2009/09) Pp. 125-134

https://doi.org/10.6649/PPB.200909_18(3).0001

摘要

應用光學與電子顯微鏡技術，比較柑橘潰瘍病菌(Xanthomonas axonopodis pv. citri)Xac-A'類型菌株XW47及Xac-A'類型菌株XW121，在柑橘葉片上所引起之非典型病斑與Xac-A類型菌株XW19所引起之典型潰瘍病斑病組織之差異。XW47菌株在墨西哥萊姆葉片上可引起典型潰瘍病斑，但在葡萄柚葉片上則引起扁平壞疽病斑；而XW121菌株在此兩種柑橘葉片上皆引起木栓化突起不具水浸狀邊緣的小病斑。以光學顯微鏡觀察由XW47菌株在墨西哥萊姆葉片上所引起之典型潰瘍病斑之病組織切片，顯示在葉肉組織裡可見許多增生及增大的細胞，並造成葉表而之突起破裂，與XW19菌株所引起之病組織相似。然而在葡萄柚葉片上，由XW47菌株所引起之扁平壞疽病斑之葉肉組織，則呈現細胞增生與組織褐色壞疽現象，然未見葉肉細胞增大及葉表向突起破裂情形。於葡萄柚及墨西哥萊姆葉片上，由XW121菌株所引起之木栓化突起小病斑的病組織切片中'，在褐色崩解的突起葉肉組織周圍，可見明顯木質化組織形成，在崩解的葉肉組織，則見細菌菌體爲大量纖維狀物質所纏聚。利用低濃度細菌懸浮液進行注射滲透接種於葡萄柚及墨西哥萊姆葉片，在病斑裡XW121菌株之菌量比XW19或XW47菌株少約10^3倍，若以較高濃度細菌懸俘液進行注射滲透接種時，在葉肉組織裡XW121菌株的菌量增加則與XW19或XW47菌株相近。雖然XW19與XW47菌株在葡萄柚葉片上引起不同的病徵，但是在病組織裡的菌量變化並無明顯差異。

關鍵字

柑橘潰瘍病 ； 細胞增大 ； 細胞增生 ； 菌量 ； 柑橘潰瘍病菌

並列摘要

Histopathology of atypical symptoms-inducing Xanthomonas axonopodis pv. citri (Xac) strains XW47 (type Xac-A') and XW121 (type Xac-A') in citrus leaves was examined with light and electron microscopy, and compared with that of a typical Asiatic citrus canker strain XW19 (type Xac-A). Strain XW47 induces typical canker lesions on leaves of Mexican lime (Citrus aurantifolia) but causes flat necrotic lesions with water soaked margin on leaves of grapefruit (C. paradisi): whereas strain XW121 induces restricted and raised corky lesions without watersoaked margin on both citrus leaves. Light microscopic examinations showed that XW47 induced hyperplasia and hypertrophy of mesophyll cells and ruptures of the epidermis as those observed in Mexican lime leaves induced by XW19. However, neither hypertrophic cells nor eruption of the epidermis were observed in the brownish necrotic and hyperplastic mesophyll tissues induced by XW47 on grapefruit leaves. A distinct layer of lignified tissues around the brownish disintegrated erumpent tissues in which masses of fibrillar matrix agglutinated with bacterial cells was observed in the sections of a restricted and raised corky lesion induced by strain XW121. Bacterial populations of strain XW121 in mesophyll tissues were approximately 10^3 folds lower than those of XW19 and XW47 under a lower inoculum concentration, but increased to those of XW19 and XW47 under a higher inoculum concentration. Although XW19 and XW47 induced distinct symptoms on grapefruit leaves, no significant difference of bacterial growth was observed.

並列關鍵字

citrus canker ； hypertrophy ； hyperplasia ； bacterial population ； Xanthomonas axonopodis pv. citri