應用植物激發物胜肽誘導草莓抵抗炭疽病之研究

草莓為台灣重要經濟水果，栽培面積多達 506 公頃。近年來草莓因種植品種及氣候的關係，使得炭疽病菌在臺灣廣泛傳播並造成嚴重的損失。因應政府「化學農藥，十年減半」政策，開發更多友善環境之替代防治策略以應用於草莓炭疽病有害生物整合管理計畫，刻不容緩。植物激發物胜肽 (plant elicitor peptides, PEPs ) 是一類植物內生性的激發物 (elicitor)，能誘發植物防禦機制以對抗生物性逆境的危害。根據前人研究，將植物激發物胜肽施用於阿拉伯芥、玉米及桃上皆可以誘導植物產生抗性並減輕植物病原菌所造成的病徵。PEPs 已在許多種植物中被發現，且對於病蟲害有防治效果，具發展潛力，前人在草莓基因體序列中亦發現有植物激發物胜肽 FaPep5 和 FaPep5b 的存在。因此，本研究之目的為測試草莓上所發現的植物激發物胜肽 FaPep5 和 FaPep5b 是否具有誘導草莓抗性以抵抗炭疽病危害之能力，除了藉由觀察處理過胜肽之草莓上炭疽病發病嚴重度來評估此二直物激發物胜肽誘發抗性效果，另外會根據後續生理生化試驗來探討 FaPep5 和 FaPep5b 可能誘發的抗病機制。結果顯示 FaPep5 及 FaPep5b 分別以濃度 100 nM 及 250 nM 即可誘導植物產生抗性有效減少炭疽病造成之病徵，而此誘發出之抗性可延續達五天之久。之後利用二氨基聯苯胺 (3, 3-diaminobenzendine, DAB) 染色發現胜肽亦會增加活性氧物質 H2O2 在葉片內的累積。而測定抗氧化酵素發現 FaPep5 在處理 24 和 36 小時後，會誘導胱甘肽還原酶 (Glutathione reductase, GR) 活性的提升，而 Fapep5b 則在處理 6 小時後 GR 活性即與對照組有顯著差異，但後續則下降並與對照組之活性類似。最後測定植物體內相關防禦基因的表現，發現兩種胜肽皆可在處理 24 小時後誘導防禦相關基因 FaNPR1 及 FaWRKY-70 的表現。本研究除了能提供 PEPs 是否具應用於草莓炭疽病防治潛力之初步成果，希望未來能找到誘導草莓大量產生 FaPep5 和 FaPep5b 之方式，使植物激發物胜肽之應用效果能更加顯著。

關鍵字

草莓；炭疽病；植物激發物胜肽；誘導抗性

並列摘要

Strawberry (Fragaria x ananassa Duchesne) is an economically important herbaceous plant belonging to family Rosaceae, the total planting area has reached 506 hectares in 2018. However, due to the high temperature and humidity in Taiwan, the anthracnose disease cause by Colletotrichum siamense was become more serious every year and lead to a great loss for strawberry farmers. To respond to the ten-year policy for cutting pesticide utilization in half, development of more environmentally friendly control measures for the integrated pest management program is a must. Plant Elicitor Peptides (PEPs) are one kind of endogenous elicitors of plants. According to previous studies, application of PEPs to Arabidopsis thaliana、Zea mays and Prunus persica can induce plant immune responses and reduce symptoms caused by different pathogens. Sequences of PEPs, including FaPep5 and FaPep5b from strawberry, have been identified in many plant species, and possess high potential to be developed into control means for pests. Therefore, this research intends to apply FaPep5 and FaPep5b to induce resistance in strawberry, and evaluate the effect based on the severity of anthracnose. The result showed that FaPep5 and FaPep5b could reduce the anthracnose symptom at the lowest concentrations of 100 nM and 250 nM, respectively. Furthermore, application of PEPs can increase the accumulation of H2O2 in strawberry leaves using the 3, 3-diaminobenzendine (DAB) staining method. FaPep5 and FaPep5b could also induce the activity of glutathione reductase (GR), which showed significant difference 24 and 36 hours after treatment of FaPep5.However, the GR activity of the FaPep5b-treated plants was significantly different from the control group at 6 hours post treatment (hpt). In addition, FaPep5 and FaPep5b can induce the expressions of NPR1 and WRKY-70 at 24 hpt. This study provides preliminary data showing the potential of PEPs on control of strawberry anthracnose. In the future, methods to intensively induce the expressions of FaPep5 and FaPep5b should be developed to strengthen the efficacy of PEPs in the field.