亞磷酸作為番茄萎凋病防治資材之潛力

Abstract

番茄為世界上最重要的經濟作物之一，然而在栽培過程中面臨多種病害的侵襲，其中由土媒性病原真菌Fusarium oxysporum f. sp. lycopersici引起的番茄萎凋病於台灣長期缺乏推薦的防治藥劑，僅能依靠抗病品種與耕作防治等其他手段。亞磷酸為國內「免登記植物保護資材」之一，用於防治多種作物的卵菌類病害已行之有年，雖然其抗病機制尚未被完全了解，但多數認為與誘發植物防禦反應有關。本研究透過in vitro實驗與盆栽實驗測試亞磷酸防治番茄萎凋病的能力，並利用qPCR分析三個番茄根部的防禦相關基因於亞磷酸處理後的表現量變化，以試圖找出亞磷酸的抗病作用機制。In vitro實驗結果顯示亞磷酸於低濃度下對番茄萎凋病菌無顯著的直接抑菌或殺菌效果，且最低抑菌濃度為3.2%，遠大於本研究測試使用的田間推薦濃度0.2% (葉面噴灑)與0.5% (土壤澆灌)，但兩個推薦濃度於盆栽實驗中皆出現顯著的防治效果。qPCR分析則顯示僅澆灌處理組的部分基因表現量則有短時間地顯著上調，但無長時間維持，因此推測亞磷酸對番茄萎凋病主要機制可能為防禦預警效應(priming)。綜上所述，本研究發現亞磷酸具有防治番茄萎凋病的潛力，並期望與現行防治策略搭配使用能進一步減少病害所造成的損害。

Tomato is one of the most important vegetable crops in the world. However, its production is threatened by various pests and diseases, including Fusarium wilt, caused by the soil-borne pathogen Fusarium oxysporum f. sp. lycopersici. In Taiwan, there are no recommended fungicides for managing this disease, leaving farmers to rely on resistant cultivars and cultural control methods. Phosphonic acid has been used to control oomycete diseases in various crops for decades. Although its mode of action is not fully understood, it is believed to induce plant defense responses. This study investigates the effectiveness of phosphonic acid against tomato Fusarium wilt through in vitro assays and pot experiments. Additionally, the expression of three defense-related genes in tomato roots was evaluated using quantitative PCR (qPCR). The in vitro tests revealed that phosphonic acid had little to no antifungal activity against F. oxysporum f. sp. lycopersici, with a minimum inhibitory concentration of 3.2%, much higher than the recommended field application rates (0.2% for foliar spray and 0.5% for soil-drench), both of which were used in this study. Despite this, phosphonic acid application significantly reduced disease severity in pot assays. qPCR analysis indicated that only the soil-drench treatment led to a temporary but significant upregulation of gene expression. These findings suggest that the effectiveness of phosphonic acid in controlling Fusarium wilt may result from the priming of plant defense responses. This study presents a potential supplementary method for managing tomato Fusarium wilt, aiming to improve disease control without chemical fungicides.