由Pseudoidium neolycopersici引起之番茄白粉病鑑定與商業品種之感病性評估

Abstract

於台灣中部網室栽培的大果番茄品種觀察到3 類型白粉病病徵，分別描述如下，類型1：於葉正面呈現典型白色粉狀病斑，並可見大量孢子；類型2：於葉正面呈現黃化不規則暈斑和壞疽，並於相應之葉背可見些許孢子；類型3：於葉正面呈現圓形到不規則狀之褐化壞疽，並可見些許孢子。經由光學顯微鏡下觀察病徵上之病兆，可見無性世代之分生孢子但並無發現有性世代之子囊孢子，利用番茄葉圓片分別對不同病徵上之病原菌進行單孢培養以供鑑定和病原性測試，依據形態特徵與internal transcribed spacer (ITS) 序列親緣演化分析，分離菌株皆鑑定為Pseudoidium neolycopersici。病原菌接種試驗結果顯示，類型1 病徵產生在接種點位於葉正面，類型2 病徵產生在接種點位於葉背，類型3 病徵發生在環境溫度和相對濕度變化較大時。此外，分離株於所有受試的大果番茄品種 (「綠鑽石」、「金吉利」、「農友301」和「鐵娘」) 皆能在葉部造成嚴重的病徵並產生大量孢子，相對於小果番茄品種 (「美女」、「玉女」、「麗金」和「金瑩」) 除了「嬌女」跟大果番茄一樣呈現強烈感病外，其他則病徵輕微且產孢少。本篇為台灣首次確認P. neolycopersici 引起番茄白粉病及其病徵之正式報導。 Three types of powdery mildew symptoms were observed on tomatoes. Type 1 symptoms displayed typical white-powdery spots with numerous spores on the upper surface of leaves. Type 2 symptoms were irregular yellowish-halo lesions on the upper surface of leaves with a few spores on the lower surface of leaves. Type 3 symptom showed circular to irregular brown lesions with a few spores on the upper surface of leaves. Conidiospores but not ascospores were microscopically observed on leaves with these types of symptoms, and several single-spore from these infected leaves were individually isolated and then cultured on tomato leaf discs for pathogen identification and pathogenicity tests. Based on morphological characteristics and phylogenetic analysis of internal transcribed spacer (ITS), the fungus was identified as Pseudoidium neolycopersici. Pathogenicity tests showed that Type 1 symptoms occurred when the inoculum was sprayed on the upper side of leaves. Type 2 symptoms occurred when the inoculum was applied on lower side of leaves. Type 3 symptoms occurred when the temperature and humidity fluctuated severely. Furthermore, P. neolycopersici caused severe leaf symptoms and produced abundant spores on large fruit tomato cultivars ‘Lu Zuan Shi’, ‘Golden Lucky’, ‘Farmers 301’ and ‘Sensation’, and caused mild symptoms and reduced sporulation on cherry tomato cultivars ‘Beauty’, ‘Jade Girl’, ‘Li Jin’ and ‘Golden Sweet’. P. neolycopersici caused severe symptoms on cv. ‘Jolly’. This study is the first report confirming the pathogenicity of P. neolycopersici on tomato in Taiwan and describing the variable symptoms of the disease.