溫度誘導反應(TIR)對草莓植株在熱逆境下存活率及抗氧化酵素活性 之影響

The Effects of Temperature Induction Response (TIR) on Survival Rate and Antioxidative Enzyme Activities of Strawberry Plants under Heat Stress

馬歇帝(Juan Francisco Mercedes de la Cruz)

指導教授 ： 方中宜

國立屏東科技大學/國際學院/熱帶農業暨國際合作系/碩士(2019年)

https://doi.org/10.6346/NPUST201900298

摘要

草莓為一種溫帶作物，其生長適溫約為10-26℃；溫度高於30℃可阻礙其生長、造成果實減產及降低果實品質。植物在酷熱環境下仍可持續生長及發展者被視為具有耐熱性，而後天耐熱性可藉由在高溫逆境來臨前先將植物暴露於非致死高溫而獲得，此過程啟動了抗氧化物及抗氧化酵素等的生理機制進而避免植物細胞膜的毀損與細胞死亡。本研究利用溫度誘導反應(一種耐熱性誘發方法) 技術來取得‘豐香’草莓的耐熱性誘導最佳條件。在高溫環境下導致90% 致死率之最低溫度為致死溫度，而本研究測得‘豐香’草莓的致死溫度為48℃/4小時；而最佳的耐熱性誘導處理為30-42℃/5小時漸進式升溫，此處理組具有最低的致死率(45%) 及最高的葉片生長率 (13.25%)，相對的未處理組有95% 致死率且所有植株生長均受阻。後續將最佳耐熱性誘導處理條件套用至另外兩個草莓品種(‘桃薰’及‘亞歷山大’)，結果顯示經處理的‘桃薰’與‘豐香’草莓的耐熱性提升幅度均大於‘亞歷山大’草莓。本實驗亦針對‘豐香’草莓控制組、溫度誘導處理組及未誘導處理組進行抗氧化酵素活性及電解質滲漏程度分析，對比不同組間抗壞血酸過氧化酶 (APX) 及過氧化氫酶 (CAT) 在熱逆境後的活性未發現有明顯變化，然而處理組的超氧化物歧化酶 (SOD) 及過氧化酶 (POD) 之活性對比控制組在熱逆境後分別呈現下降與上升趨勢。在電解質滲漏方面，未誘導處理組有最高的電解質滲漏率(37.9%)，高於高溫誘導處理組(22.15%)及控制組(12.56%)。另外，針對不同TIR步驟進行化驗分析，發現‘豐香’草莓在 30-39°C 處理後之APX及POD活性達到最高峰，。隨後將原始T1處理之30-42℃/5小時調整為優化後的30-39℃/4小時，發現植株死亡率由原本45%下降為30%，葉片生長率也由原本13.25%提升為15.33%。本研究描述如何利用標準化及最佳化之溫度誘導反應技術來誘導草莓植株的耐熱性。

關鍵字

後天耐熱性 ； 抗氧化物活性 ； 耐熱性 ； 草莓屬

並列摘要

Strawberry is a temperate crop whose optimum growth temperatures fluctuate between 10 and 26°C. Temperatures higher than 30°C tend to reduce its growth, yield and fruit quality. Plants able to grow and develop under severe temperatures have been defined as thermotolerants. Acquired thermotolerance has been obtained by subjecting the plants to high sub-lethal temperatures before exposing to a future heat stress. This process involves the activation of several mechanisms that may increase enzymatic and non-enzymatic antioxidant activities, and avoid membrane damage and subsequent cell and plant death. In this study, the temperature induction response (TIR) technique, a thermotolerance induction method, was optimized with the strawberry cultivar ‘Toyonoka’. The lowest temperature treatment which caused more than 90% plant mortality was defined as the lethal temperature which was 48°C/4h for ‘Toyonoka’ strawberry plants. The treatment which yielded the lowest mortality (45%) and highest leaf growth
(13.25%) rates was gradually increasing the temperature from 30 to 42°C for 5 hours. The non-induced treatment caused 95% mortality and totally interrupted plant growth. Then the selected temperature induction treatment was applied on other two strawberry cultivars (‘Toukun’ and ‘Alexandria’). The induced ‘Toukun’ and ‘Toyonoka’ plants were found to be more heat tolerant than the induced ‘Alexandria’ plants. Activities of four enzymatic antioxidants and extent of electrolyte leakage were determined for control, induced and non-induced ‘Toyonoka’ strawberry plants. No significant differences were recorded in the ascorbate peroxidase (APX) and catalase (CAT) activities of stressed (induced and non-induced) and unstressed plants (control), while the superoxide dismutase (SOD) activity decreased and the peroxidase (POD) activity increased under stress conditions. Higher percentage of electrolyte leakage was observed with the non-induced plants (37.92%) than the induced (22.15%) and control (12.56%) plants. Finally, optimization of TIR was conducted by evaluating the enzymatic antioxidant activities at the different steps of the TIR process. Results showed that the APX and POD activities peaked at 30-39°C. The optimized induction temperature treatment was then modified into 30 to 39°C for 4 hours, at which mortality of ‘Toyonoka’ strawberry plants was reduced to 30% and leaf growth was increased up to 15.33% after adoption of the new treatment. This study describes the standardization and optimization of the TIR technique for inducing thermotolerance in strawberry.

並列關鍵字

acquired thermotolerance ； antioxidant activity ； heat tolerance ； Fragaria

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