利用gene silencing方式探討atSKD1基因對阿拉伯芥容忍高鹽逆境之影響

Abstract

當植物遭受到高鹽逆境時，細胞外水分潛勢下降，導致胞內水分含量下降，細胞膨壓喪失，使得細胞延長的狀況減緩。前人研究發現耐鹽植物冰花(Mesembryanthemum crystallinum L.)中具有一個mcSKD1基因參與了冰花耐鹽機制中維持離子平衡的途徑，而SKD1基因在酵母菌中亦證實參與了endosomal protein sorting的機制。本篇論文使用一與mcSKD1基因具高度相同度的阿拉伯芥atSKD1基因，而以酵母菌互補試驗得知atSKD1基因亦具有互補缺鉀性狀的能力。 將反向的atSKD1基因轉入阿拉伯芥中，使得轉殖株中atSKD1的表現量及蛋白累積量下降，進而比較野生型阿拉伯芥與轉殖株在不同鹽濃度下生長的狀況，結果發現atSKD1表現量下降的轉殖株因高鹽而根生長減緩的程度明顯比野生型阿拉伯芥來得大，顯示atSKD1基因參與阿拉伯芥在高鹽環境下調節離子平衡的protein sorting過程。

When plants are under salt stress, water potential in soil decreased resulting water loss from cell, decrease in tugor pressure, and growth retardation. A salt-induced gene, mcSKD1(suppressor of K+ growth defect), isolated from halophyte Mesembryanthemum crystallinum L. has been demonstrated in facilitation of K+ uptake under high saline environment. In yeast, SKD1 homolog has been shown to participate in the last step of endosomal protein sorting process. A gene atSKD1 found in Arabidopsis database has high identity to mcSKD1 gene. By yeast complementation, atSKD1 gene showed similar ability to mcSKD1 in suppressing potassium uptake defective phenotype of yeast mutant. By transforming antisense atSKD1 gene to Arabidopsis, both transcript and protein levels of atSKD1 were decreased. The antisense mutant was more sensitive to salt as shown by the decrease in root length under salt stress. The result suggest that SKD1 is involved in the maintenance of ion homeostasis under high saline environment.