番茄細菌性斑點病菌株間之表現型差異性探討

番茄是台灣主要的蔬果作物之一，在種植期間常受到細菌性斑點病菌為害。台灣存在Xanthomonas euvesicatoria、X. perforans與X. vesicatoria等3種細菌性斑點病菌，目前感染番茄的菌種有X. euvesicatoria及X. perforans。近年來X. perforans在番茄上已成為優勢菌種。本研究在觀察X. euvesicatoria XTN30與X. perforans XTN425兩菌種在NA及523培養基之菌落形態，並利用浸泡接種將XTN30與XTN425菌株分別接種'L390'與'CHT1520'番茄植株，藉由病徵表現及病害嚴重程度，以探討菌種之間的致病力差異，同時觀察番茄品種之間的葉表構造，以瞭解其與病害表現的關聯性。研究結果顯示XTN30與XTN425菌株生長在NA與523培養基的菌落形態相似，但XTN425菌落顏色較XTN30深。接種後10天，兩種菌株皆會引起番茄葉片的斑點病徵，且圓形病斑外圍具有黃暈，而XTN425菌株能夠導致病斑處形成孔洞。以XTN30與XTN425菌株接種'L390'番茄的平均罹病度分別為15.5%與47.2%，而接種'CHT1520'番茄的平均罹病度分別為22.0%與69.1%，顯示XTN425菌株對番茄的危害程度顯著高於XTN30菌株，且番茄品種'CHT1520'較'L390'感病。此外，經由解剖顯微鏡的葉表構造觀察，發現'CHT1520'葉表布滿短毛茸及零星的長毛茸，而'L390'葉表僅有零星的長毛茸，推測葉表毛茸多寡可能與感病性高低有關。本研究結果顯示X. euvesicatoria XTN30與X. perforans XTN425存在表現型差異，而X. perforansXTN425對番茄具有較強的致病力，且會引起較嚴重的葉部病徵。

關鍵字

番茄；細菌性斑點病；表現型；菌落形態；浸泡接種；葉表毛茸

並列摘要

Tomato is one of the major vegetable and fruit crops in Taiwan, and is often damaged by bacterial spot pathogen in cultivation. In Taiwan, there are three species of bacterial spot pathogen with Xanthomonas euvesicatoria, X. perforans and X. vesicatoria. The pathogens currently infecting tomatoes are X. euvesicatoria and X. perforans. X. perforans has become a dominant species on tomato in recent years. In this study, we observed the colony morphology of X. euvesicatoria XTN30 and X. perforans XTN425 on NA and 523 culture plates, and inoculated the 'L390' and 'CHT1520' tomato plants with the XTN30 and XTN425 strains by dipping method, respectively. The pathogenicity differences of both strains were explored according to the symptom and disease severity, and the leaf surface structure between tomato varieties was observed to understand its association with disease expression. The results show that the colony morphology of XTN30 and XTN425 strains on NA and 523 culture plates were similar, but XTN425 colonies were darker than XTN30. Both strains caused spot symptoms on tomato leaves with a yellowish halo around the circular lesions at 10 days after inoculation. And the XTN425 strain can form hole in the center of the lesions. The average disease severity of 'L390' tomato inoculated with XTN30 and XTN425 strains was 15.5% and 47.2%, respectively, while the average disease severity of the inoculated 'CHT1520' tomato was separately 22.0% and 69.1%. The results indicate the XTN425 strain was signifi cantly more harmful to tomatoes than the XTN30 strain and implied the variety 'CHT1520' was more susceptible than 'L390'. In addition, according to the observation of dissecting microscope, we found that the leaf surface of 'CHT1520' was covered with short leaf trichomes and sporadic tall leaf trichomes, while the leaf surface of 'L390' had only sporadic tall leaf trichomes. It is speculated that the amount of leaf trichome may be related to the level of susceptibility. The results of this study show that there are phenotypic diff erences between X. euvesicatoria XTN30 and X. perforans XTN425, and X. perforans XTN425 has a strong pathogenicity to tomato and make more severe leaf symptoms.

並列關鍵字

tomato ； bacterial spot ； phenotype ； colony morphology ； dipping inoculation ； leaf trichomes

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