硫氧化還原蛋白(Thioredoxin, 簡稱Trx)是一類利用硫基(Thiol group)氧化還原反應(2SH←→S-S)調節細胞氧化還原狀態的蛋白,與其專一性的Trx還原酶(The NADPH-dependent thioredoxin reductase, 簡稱NTR)構成NTR/Trx系統,在植物氧化逆境抗性反應中扮演重要的角色。Sulfolobus solfataricus是一種生長在極端環境的古生菌,為了解此系統對植物逆境抗性之影響,本研究將S. solfataricus 兩個Trx基因SsTrxA1、SsTrxA2,以及一個NTR基因SsTrxB3,分別利用35S啟動子驅動構築成可在植物大量表現的質粒,包括OE-SsTrxA1、OE-SsTrxA2、OE-SsTrxB3 、OE- SsTrxA1+ SsTrxB3、OE- SsTrxA2+SsTrxB3等5個質粒,並利用農桿菌轉殖大量表現在阿拉伯芥,以分析轉殖植物對逆境之抗性。RT-PCR分析結果顯示,五種質粒均可成功的大量表現在阿拉伯芥植株中,各基因構築均可獲得6個以上轉殖系。轉殖株經過鎘、巴拉刈處理後,顯示SsTrxB3 與 SsTrxA2+SsTrxB3轉殖株有較佳的逆境抗性,在逆境下與未轉殖植株比較,有較長的根長與較大的鮮重。此外,熱逆境分析結果顯示OE- SsTrxA2B3具有較佳的先天耐熱性。這些結果顯示來自S. solfataricus的NTR/Trx系統能提高植物的逆境抗性,未來應具有潛力應用於增加作物耐多重逆境抗性。
NADPH-dependent thioredoxin reductase/Thioredoxin (NTR/Trx) system catalyzes disulfide-bond reduction to regulate the redox status of cells, ubiquitously exists in all organisms and involves in oxidative stress response. The NTR/Trx system of a hyperthermophilic archaeon, Sulfolobus solfataricus, has been found to play a major role in its extremely thermal tolerance. To study the impact of S. solfataricus NTR/Trx system on plant abiotic stress tolerance, S. solfataricus NTR/Trx system genes (two Trx genes:SsTrxA1, SsTrxA2 and one NTR gene :SsTrxB3) were solely or simultaneously overexpressed in Arabidopsis thaliana to evaluate their roles in abiotic stress tolerance. Five plasmids including SsTrxA1, SsTrxA2, SsTrxB3, SsTrxA1+ SsTrxB3 and SsTrxA2+SsTrxB3 under the control of a CaMV 35S promoter were constructed and transformed to Arabidopsis by Agrobacterium tumefaciens. At least 6 transgenic lines were obtained for each construct and most of them showed highly accumulation of NTR or Trx mRNA. Functional analysis indicated that OE-SsTrxB3 and OE-SsTrxA2B3 plants exhibited enhanced tolerance of transgenic plants to Cd and paraquat.Moreover, SsTrxA2+SsTrxB3 plants also showed increased thermal tolerance. Taken together, the S. solfataricus NTR/Trx system is able to enhance stress tolerance in Arabidopsis. This system may be applied for the development of new strategies to enhance crop tolerance to multiple stresses.