作物對除草劑巴拉刈之抗性與其調控活化氧族之解毒能力有關。先前研究顯示抑制OsMAPK3 (Mitogen activated protein kinase 3)基因之表現會降低抗氧化酵素的活性,降低水稻對非生物逆境之耐受性。因此本試驗將ABA誘導OsMAPK3表現之農桿菌質體,轉殖於臺農67號水稻中,探討水稻轉殖株之抗氧化酵素活性是否增加,進而得以提升水稻對巴拉刈之抗性。由RT-PCR得知,內生OsMAPK3基因可受H2O2、ABA誘導;巴拉刈則無影響。同時OsMAPK3轉殖水稻經ABA處理後可有效誘導該基因之表現。比較非轉殖株與OsMAPK3轉殖水稻間抗氧化酵素活性之差別,發現轉殖水稻Catalase (CAT)和Ascorbate peroxidase(APX)的活性均較非轉殖株高,而H2O2含量則較低。以巴拉刈處理非轉殖與OsMAPK3過量表現之稻株,結果顯示轉殖水稻的Fv/Fm比值與葉綠素含量都比非轉殖水稻高,生長外觀相對較佳。顯示大量表現OsMAPK3可提升水稻抗氧化酵素活性進因增加水稻對巴拉刈之抗性。綜合而言,本試驗結果指出調控水稻MAPK之訊息路徑,改變其抗氧化能力可作為未來有效提升作物除草劑抗性之可能途徑。
In crops, the detoxification capability especially in eliminating the accumulation of reactive oxygen species, is highly linked to the herbicide tolerance of paraquat. Previous data showed that by inhibition of OsMAPK3 expression in rice resulted in decrease of antioxidant enzymatic activities and reduced abiotic stress tolerance. Hence, in this study we tested whether by ABA-induced OsMAPK3 expression in rice can lead to increase of antioxidant enzymatic activities and further enhance paraquat resistance. RT-PCR analysis indicated that the endogenous OsMAPK3 expression was induced by H2O2 and ABA but not paraquat. Meanwhile, after ABA treatment the OsMAPK3 expression was effectively induced in transgenic rice. Antioxidant enzymatic activities analysis showed that catalase (CAT) and ascrobate peroxidase (APX) activities were both increased and the H2O2 content was reduced in transformant. Also, OsMAPK3 transformant displayed higher PSII electron transfer efficiency (Fv/Fm) and chlorophyll content after paraquat treatment and grew better than control. These results suggest that up-regulation of OsMAPK3 not only increased the oxidative-induced antioxidant defense but also improved rice paraquat tolerance. Taken together, by manipulation the expression of MAPK gene and changing the antioxidant capacity may provide an alternative for producing transgenic herbicide tolerance crops in future.