評估氣候變遷下褐飛蝨抗蟲基因BPH17以及BPH20近同源系之抗性能力

Abstract

褐飛蝨(Nilaparvata lugens Stål)為亞洲水稻主要害蟲之一，當族群過多時會影響水稻產量。褐飛蝨為專食性害蟲，藉由刺吸水稻莖桿吸食汁液獲得生長所需養分，主要宿主為水稻和野生稻。透過栽培抗褐飛蝨水稻品種，減緩褐飛蝨族群成長速度以及減少產量損失。前人研究指出隨環境溫度提升部份抗蟲基因會失去抗性。聯合國政府間氣候變遷專門委員會(IPCC)預測未來環境的大氣二氧化碳濃度將會增加也因而導致大氣平均氣溫上升。本研究欲了解氣候變遷是否會導致水稻抗褐飛蝨基因失去抗性。透過種植IR24 NILs (near-isogenic lines)於模擬未來環境中，對多個抗BPH基因進行評估。本研究參照IPCC預測建構模擬環境，環境設定分別為(1) Ambient：模擬目前環境氣溫30℃/25℃ (日/夜)、大氣CO2 濃度500 ppm；(2)2050：模擬2050年環境氣溫32℃/27℃ (日/夜)、大氣CO2濃度600 ppm；(3) 2100：模擬2100年環境氣溫35℃/30℃ (日/夜)、大氣CO2濃度1000 ppm。透過水稻秧苗期抗性檢定，發現NILs中NIL-BPH17、NIL-BPH18+32、NIL-BPH9+32抗蟲能力不受環境影響，而NIL-bph4、NIL-BPH9、NIL-BPH10、NIL-BPH21在高溫高二氧化碳的環境下減弱其抗蟲效力。此外，分別針對NIL-BPH17和NIL-BPH20進行抗生性和抗棲性實驗。結果顯示NIL-BPH17在高溫高二氧化碳的環境下仍可有母蟲吸食水稻韌皮部的抑制效力，並維持對褐飛蝨若蟲的忌避效果。但母蟲產卵率、若蟲存活率、若蟲族群相對生長速率等實驗結果則顯示會隨環境影響而失去抗性。NIL-BPH20對褐飛蝨母蟲產卵率和若蟲族群生長速率無抑制作用，而在Ambient環境中可抑制母蟲吸食水稻韌皮部，2050環境中可抑制若蟲存活率，但隨環境影響將沒有抗性。此外，NIL-BPH20於Ambient環境中對褐飛蝨無忌避效果，但於2050和2100環境中則有忌避效果。根據本研究的實驗結果證明氣候變遷會影響抗蟲基因的抗蟲能力。本研究可提供給育種家有關於環境對於抗蟲基因的影響。

The brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is one of the most serious pests on rice in Asia. The outbreak of BPH would cause the yield loss of rice. BPH is the specialist which feeds on the leaf sheath to obtain nutrients. Its host range is limited on rice and its relatives (i.e. wild rice). For the pest management, planting BPH-resistant variety could control the BPH population and further low the yield loss. Previous studies showed that resistance ability of the insect-resistant gene would get loss due to the temperature increasing. Intergovernmental Panel on Climate Change (IPCC) predicted that atmosphere temperature and CO2 concentration will increase in the future. In this study, we would like to know whether the BPH-resistant genes would be affected by the climate change. Thus, a series of IR24 near-isogenic lines (NILs) planting in the corresponding environments were used to evaluate their performance. Based on IPCC prediction, three environments were set up as follows: Ambient (ambient environment): 30℃/25℃ (day temperature /night temperature), CO2 concentration of 500 ppm; 2050 (the prediction environment in the year 2050): 32℃/27℃ (day temperature /night temperature), CO2 concentration 600 ppm; 2100 (the prediction environment in the year 2100): 35℃/30℃ (day temperature /night temperature), CO2 concentration 1000 ppm. In the standard seedbox screening test (SSST), we found that NIL-BPH17, NIL-BPH18+32, NIL-BPH9+32 showed stable resistance towards the environments. However, NIL-bph4, NIL-BPH9, NIL-BPH10, NIL-BPH21 were lower their resistant ability towards the environments. Two NILs (NIL-BPH17 and NIL-BPH20) were chosen for the antibiosis and antixenosis studies. In NIL-BPH17, the inhibiting ability of BPH feeding on the phloem and non-preference effect would not be affected by the environments. However, the inhibition abilities on female fecundity, nymph survival rate and nymph population growth rate would lose the effect due to the climate change. In NIL-BPH20, it has no inhibition effect on BPH female fecundity and nymph population growth rate. Under ambient environment, NIL-BPH20 has the inhibition ability of BPH feeding on the phloem. In 2050, NIL-BPH20 would inhibit the nymph survival rate. However, these inhibitions would not invalid due to the climate change. In addition, NIL-BPH20 did not have any inhibition effect on the BPH choice test in the Ambient condition. But in 2050 and 2100, few nymphs would choose the plants of NIL-BPH20. Based on our study, the environmental change would affect the resistant ability of the insect-resistant genes. These results would provide plant breeders the information about the insect-resistant genes responding to the environments.