Distinct Roles of Abscisic Acid in Rice Seedlings during Cadmium Stress at High Temperature

高溫下脫落酸在水稻幼苗鎘逆境所扮演之功能

許奕婷(Yi-Ting Hsu) ； 高景輝(Ching-Huei Kao)

《Botanical Studies》 49卷4期 (2008/10) Pp. 335-342

摘要

氯化鎘在高溫(35/30℃)下處理台中在來1號(TN1)與台農67號(TNG67)水稻幼苗。鎘毒害以葉綠素與蛋白質含量降低程度為指標。結果顯示TN1是不耐鎘品種，而TNG67是耐鎘品種。氯化鎘在高溫下處理TN1與TNG67幼苗，脫落酸含量明顯增加。類胡蘿蔔素合成抑制劑Fluridone (Flu)處理TNG67幼苗可降低鎘造成之脫落酸累積，增加蒸散速率與鎘含量以及增加鎘之毒害。外加脫落酸處理可克服Flu所增加之鎘毒害。而在高溫下Flu處理TN1幼苗可降低鎘所引起脫落酸之累積，以及鎘毒害。這些Flu之效應可被外加脫落酸所抵消。高溫下外加脫落酸處理可引起TN1幼苗之黃化現象（類似鎘毒害），但對TNG67幼苗不會造成黃化現象。文中對脫落酸在高溫鎘逆境下所扮演的角色做一詳細的討論。

關鍵字

脫落酸 ； 鎘 ； 水稻 ； 高溫

並列摘要

Cd toxicity was judged by the decrease in chlorophyll and protein contents. Twelve-dayold seedlings of rice cultivars [Tainung 67 (TNG67) and Taichung Native 1 (TN1)] were treated with or without CdCl2 at high temperature (35/30℃ day/night). The results indicated that at high temperature, TNG 67 seedlings are a Cd-tolerant cultivar while TN1 seedlings are Cd-sensitive. On treatment with CdCl2, the abscisic acid (ABA) contents increased in the leaves of both TNG67 and TN1 seedlings grown at high temperature. Fluridone (Flu), an inhibitor of carotenoid biosynthesis, treatment, reduced ABA accumulation, increased transpiration rate and Cd content, and decreased Cd tolerance of TNG67 seedlings grown at high temperature. Flu's effect on Cd toxicity of TNG 67 seedlings was reversed by the application of ABA. For TN1 rice seedlings grown at high temperature, Flu treatment resulted in less Cd-induced ABA accumulation, as well as toxicity. These Flu effects were reversible by application of ABA. However, Flu treatment did not reduce Cd content in the leaves of TN1 seedlings grown at high temperature. Exogenous application of ABA at high temperature provoked chlorosis, a symptom of Cd toxicity, in the leaves of TN1, but not in TNG67 seedlings. Suggested roles for endogenous ABA in Cd tolerance of TNG67 seedlings and Cd toxicity of TN1 seedlings are discussed.

並列關鍵字

Abscisic acid ； Cadmium ； High temperature ； Oryza sativa