影響菸草粉蝨取食獲得TYLCTHV和ToLCTV的生物因子

Abstract

番茄黃化捲葉病毒是一群嚴重威脅全球番茄生產的病毒。在台灣番茄田間最常見的病毒為番茄黃化捲葉泰國病毒 (tomato yellow leaf curl Thailand virus, TYLCTHV) 與番茄捲葉臺灣病毒 (tomato leaf curl Taiwan virus, ToLCTV)，大約40%有病徵的番茄植株被這兩種病毒感染。由於這群病毒均僅依賴菸草粉蝨 (Bemisia tabaci) 傳播，因此菸草粉蝨與病毒之間的相互作用對病毒的傳播和流行有重要影響。本研究的目的是檢驗：1）粉蝨取食時間對菸草粉蝨獲得TYLCTHV和ToLCTV的影響；2）病源株病毒量對菸草粉蝨獲得TYLCTHV和ToLCTV的影響；3）複合感染病源植株的TYLCTHV和ToLCTV比例對菸草粉蝨獲得病毒的影響。結果顯示，在單一和複合感染植物上，TYLCTHV和ToLCTV在菸草粉蝨中腸和主唾腺的病毒量增加隨著獲毒時間的而增加，且在48 小時前病毒量已達到平原期。無論是在單一還是複合感染植物中，在整個獲毒期間TYLCTHV在中腸和主唾腺中的病毒量均顯著高於ToLCTV。此外，菸草粉蝨中腸的 TYLCTHV 與 ToLCTV 病毒量增加皆隨病源植株病毒量而增加，而主唾腺的病毒量也顯示類似的結果。最後，無論複合感染病源植物中的病毒比例如何，菸草粉蝨的中腸和主唾腺獲得TYLCTHV的效率均高於ToLCTV。這些發現突顯了TYLCTHV在獲毒和在粉蝨體內移動過程中的優勢。研究結果將有助於制定和實施綜合病害管理（IDM）計畫，如利用殺蟲劑或忌避劑減少粉蝨取食時間、移除病株以減少病源植物、使用抗病毒的植物品系以降低罹病植株中的病毒量、利用生物刺激素或栽培管理強化植物的抗病毒能力。

Tomato yellow leaf curl viruses are a group of viruses that seriously threaten global tomato production. In Taiwan, the most common viruses in the tomato field are tomato yellow leaf curl Thailand virus (TYLCTHV) and tomato leaf curl Taiwan virus (ToLCTV) are, with about 40% of symtomatic plants infected by both viruses. Since these viruses only rely on Bemisia tabaci for transmission, the interaction between whiteflies and the viruses has an important impact on the spread and prevalence of the viruses. The objectives of this study were to examine: 1) the effects of feeding time on the acquisition of TYLCTHV and ToLCTV by B. tabaci; 2) the effects of viral load of virus source plants on the acquisition of TYLCTHV and ToLCTV by B. tabaci; 3) the effects of the ratios of TYLCTHV and ToLCTV in coinfected source plants on virus acquisition by B. tabaci. The results showed that the titers of TYLCTHV and ToLCTV in the midgut and primary salivary gland (PSG) of B. tabaci increased with acquisition time on both single and coinfected plants, and the titers of viruses reached plateau before 48 h. The titers of TYLCTHV in the midgut and PSG were significantly higher than those of ToLCTV throughout the feeding period on both single and coinfected plants. Further, in the whitefly’s midgut, the titers of TYLCTHV and ToLCTV increased as the viral load in tomato plants increased, and similar results were obtained in the whitefly’s PSG. Last, regardless of the virus ratio in coinfected source plants, the midgut and PSG of whitefly acquired TYLCTHV more efficiently than ToLCTV. These findings highlight the advantages of TYLCTHV over ToLCTV in the process of virus acquisition and translocation. The results will apply to developing and implementing integrated disease management (IDM) program, such as using insecticides or repellents to reduce the feeding time of whiteflies, removing diseased plants to decrease source plants, using virus-resistant plant varieties to lower the virus load in infected plants, using biostimulants or cultivation management to enhance the plant's resistance to viruses.