台灣馬鈴薯病毒現況調查與探討高溫對馬鈴薯Y病毒與馬鈴薯S病毒感染之影響

Abstract

馬鈴薯為全球重要的糧食作物，然而其生產易受多種病毒威脅，包括馬鈴薯Y病毒 (potato virus Y, PVY)、馬鈴薯S病毒 (potato virus S, PVS)、馬鈴薯X病毒 (potato virus X, PVX) 、馬鈴薯A病毒 (potato virus A, PVA)、馬鈴薯M病毒 (potato virus M, PVM) 與馬鈴薯捲葉病毒 (potato leafroll virus, PLRV) 等。在台灣，關於馬鈴薯病毒感染現況及其生物與分子特性之資訊仍相當有限。此外，氣候變遷所導致的高溫亦可能影響植物與病毒間的交互作用，但不同馬鈴薯品種在高溫下之病毒感染變化仍未被充分釐清。本研究主要聚焦於兩項目標：(1) 進行田間調查以了解台灣地區的馬鈴薯病毒現況，並分析其生物學與分子特性；(2) 探討高溫對病毒與寄主交互作用之影響。田間調查結果顯示，PVY為台灣最普遍的馬鈴薯病毒，其次為PVS與PVX。病原性分析、病毒系統鑑定與親緣演化樹分析結果指出，PVY-33N-Wi (本研究使用之PVY代表病毒系統) 會在菸草 (Nicotiana benthamiana) 上引起嚴重病徵，而 PVS-67I (本研究使用之PVS代表病毒系統) 則造成輕微矮化現象。進一步接種試驗顯示，PVY-33N-Wi 感染克尼伯 (Kennebec) 與台農一號兩品種時，僅在克尼伯上造成葉片變形之病徵、地上部鮮重下降17% 及塊莖產量減少50%；但在台農一號上無顯著影響。相對地，PVS-67I僅使台農一號植株高度略微增加。在溫度與病毒交互作用分析中，高溫處理本身即顯著降低根部鮮重並增加植株高度。在高溫下，PVY-33N-Wi在克尼伯感染初期累積量增加，可能與水楊酸 (Salicylic acid, SA) 相關抗病毒路徑受到抑制有關；而在台農一號中，PVY-33N-Wi在感染後期累積量反而下降，其抗性機制可能與SA或RNA介導沉默作用 (RNA interference, RNAi) 路徑較無關聯。至於PVS-67I，於高溫下兩品種皆呈現感染初期累積量增加、後期下降之趨勢，此現象可能與初期之SA與部分RNAi相關基因表現下調、而後期之RNAi 路徑相關基因被誘導表現有關。綜上所述，PVY為台灣主要的馬鈴薯病毒，高溫會顯著影響馬鈴薯生理表現，並導致不同品種間在病毒累積動態上的差異，可能與SA與部分RNAi路徑中基因表現的差異調控有關。為因應氣候升溫所帶來的挑戰，台灣馬鈴薯產業未來應優先發展兼具高溫耐受性與抗病毒能力之在地品種，以確保生產穩定與永續經營。

Potato is a globally important food crop. However, the potato production is threatened by several viruses including potato viruses Y, S, A, M and X (PVY, PVS, PVA, PVM and PVX), and potato leafroll virus (PLRV). In Taiwan, current information regarding the potato virus infection status and their biological and molecular characteristics remains limited. Moreover, the climate change-induced high temperature influences plant-virus interaction. However, the effect of high temperature on potato virus infection dynamics in different potato cultivars remain largely elusive. This study focused on two major objectives: (1) conducting field survey to identify potato viruses in Taiwan and analyzing their biological and molecular characteristics, and (2) investigating the effects of high temperature on virus–host interactions. In this study, the field survey results revealed that PVY is the most prevalent potato virus in Taiwan, followed by PVS and PVX. Pathogenicity, strain typing, and phylogenetic analysis revealed that PVY-33N-Wi (representative PVY strain used in this study) induced severe symptoms, while PVS-67I (representative PVS strain used in this study) caused mild stunting in Nicotiana benthamiana. Inoculation of PVY-33N-Wi on Kennebec and Tainung No. 1 potato cultivars showed that PVY-33N-Wi caused deformed leaves symptoms, a 17% reduction in shoot weight and 50% yield loss in Kennebec, but had no significant effect on Tainung No. 1. In contrast, PVS-67I infection only slightly increased plant height in Tainung No. 1. In the temperature–virus interaction assay, high temperature alone significantly reduced root weight and increased plant height in both Kennebec and Tainung No. 1. Further analysis showed that PVY-33N-Wi accumulated more in Kennebec under high temperature at early infection stages, which may associate with the suppression of salicylic acid (SA)-related antiviral immune pathway. In Tainung No. 1, the accumulation of PVY-33N-Wi was decreased under high temperature at later infection stages, which may not primarily involve the SA and RNA interference (RNAi) pathway. For the PVS-67I, PVS-67I accumulate more at early infection stages but decrease at later infection stages under high temperature in both Kennebec and Tainung No. 1. The result may be associated with the early suppression of SA-related gene and some RNAi-related genes, followed by the induction of certain RNAi-related gene at later infection stages under high temperature. In conclusion, PVY is the predominant potato virus in Taiwan. High temperature significantly affects potato physiology and leads to cultivar-specific difference in the accumulation dynamics of PVY and PVS, possibly due to differential expression of SA and RNAi-related gene. To address the challenges posed by rising temperatures, future development of the potato industry in Taiwan should prioritize the local breeding of heat-tolerant and virus-resistant cultivars to ensure sustainable production.