蘭花菌根及藥劑處理與蝴蝶蘭及朵麗蝶蘭抗蕙蘭嵌紋病毒之相關性

Abstract

蕙蘭嵌紋病毒及齒舌蘭輪斑病毒在全世界蘭花非常普遍。蝴蝶蘭是台灣重要的外銷花卉。病毒感染會降低植株生長及開花品質，影響商業價值。本研究之目的為提升蝴蝶蘭及朵麗蝶蘭植株抵抗蕙蘭嵌紋病毒之能力，進行此病毒臨界感染濃度之確定，並探討化學藥劑及蘭花菌根提高蘭株抵抗此病毒之可能性。選用已知為未感染蕙蘭嵌紋病毒及齒舌蘭輪斑病毒之三種蘭花瓶苗，分別是以白花蝴蝶蘭KC1935（Phalaenopsis Taisuco Kaaladian × Phalaenopsis Grace Palm）、大白花蝴蝶蘭KC 1943（Phalaenopsis Taihort Snowdian ‘Minho’× Phalaenopsis Yukimai Dream Morida）與明和公主朵麗蝶蘭KC3925（Doritaenopsis Minho Princess）。以蕙蘭嵌紋病毒RNA五種濃度（0.01、0.1、0.5、1及2 μg/μl）接種，經一個月生長，再經反轉錄－聚合酵素鏈鎖反應（RT-PCR）檢測，確定白花蝴蝶蘭KC1935與明和公主朵麗蝶蘭KC3925對於蕙蘭嵌紋病毒之適合接種濃度皆為0.5 μg/μl；另一栽培種大白花蝴蝶蘭KC1943對於蕙蘭嵌紋病毒之適合接種濃度則為0.1 μg/μl。探討蘭花菌根與化學藥劑抗蕙蘭嵌紋病毒之可能性，分為三種處理，即蘭花植株先各別接種一種絲核菌屬蘭共生真菌（R01, R02, R04, R15, R19）或噴灑不同濃度之甲殼素、水楊酸，經兩個月後，再以蕙蘭嵌紋病毒適合接種濃度（0.5 或 0.1 μg/μl））進行接種，待一個月後以反轉錄－聚合酵素鏈鎖反應（RT-PCR）進行檢測。研究結果顯示，以接種R04配合一個月噴灑一次水楊酸（1 mM）或每兩週噴灑一次甲殼素2 ml/L或水楊酸1 mM、2 mM之四種處理提昇植株對於蕙蘭嵌紋病毒之抗性效果最佳，皆可保持無病毒狀態。試驗結果亦顯示蘭花栽培種間對於病毒抗性並不一致，建議不同蘭花栽培種植株對水楊酸、甲殼素或蘭花菌根菌之反應可能有所不同，故對新栽培種應先測試不同種類蘭菌、藥劑濃度及施藥間隔。

Cymbidium mosaic virus and Odontoglossum ringspot virus are the most prevalent infecting orchids worldwide. Phalaenopsis and Doritaenopsis spp. are important export orchids in Taiwan. The viruses would reduce plant vigor and lower flower quality, thus affects economic value. The objectives of this study were trying to increase Cymbidium mosaic virus（CymMV）resistance of both Phalaenopsis and Doritaenopsis spp. CymMV proper inoculation concentration for all cultivars were determined, and to investigate the effects of chemical treatment and orchid mycorrhiza on CymMV resistance. The inoculation of CymMV RNA was used to determine proper inoculation concentration for each cultivar. Three cultivars of virus free orchids which were pre-detected by RT-PCR method including KC1935（Phalaenopsis Taisuco Kaaladian × Phalaenopsis Grace Palm）, KC1943（Phalaenopsis Taihort Snowdian ‘Minho’× Phalaenopsis Yukimai Dream Morida）and KC3925（Doritaenopsis Minho Princess）. After the inoculation of five concentrations（0.01、0.1、0.5、1 and 2 μg/μl）of CymMV RNA for one mouth, CymMV proper inoculation concentration were detected by RT-PCR. Results showed that the CymMV proper inoculation concentration of KC1935 and KC3925 were 0.5 μg/μl, but for KC1943 was 0.1 μg/μl. Effects of chemical treatments and orchid mycorrhiza on CymMV resistance were investigated. The study including three parts, i.e. the orchid plants were inoculated with one species of Rhizoctoria spp. fungi（R01, R02, R04, R15 and R19）or spraying with different concentrations of chitosan or salicylic acid. After two months, CymMV proper inoculation concentration（0.5 or 0.1 μg/μl）were inoculated to the leaves of three orchid cultivars, then examined virus infection by RT-PCR for another one month. Results showed that either inoculated the orchid plants with R04, then spray with salicylic acid 1 mM per month or biweekly spraying with chitosan 2 ml/L or salicylic acid 1 mM or 2 mM, could very effectively increase the orchid plants to resist CymMV and keep the plant in virus-free state. Results also showed that the resistance of orchid plants to CymMV varied with orchid cultivars. It was suggested that each orchid cultivar might show different response for salicylic acid, chitosan or orchid mycorrhizal fungi, thus for new cultivar, the OMFs, chemical treatment concentrations and intervals should be tested in advance.