澱粉(starch)為葡葡糖(glucose)所構成之巨分子，為植物體內碳水化合物最主要的儲存形式。位於葉綠體中的澱粉於白天堆積，晚上水解，亦稱為暫存性澱粉(transitory starch)，但目前對於暫存性澱粉的代謝調控機制所知仍少。糖類(sugar)可提供能量促進植物生長；但高濃度的糖類卻會抑制植物生長並誘導澱粉合成基因ApL3(AGPase large subunit 3)表現，造成澱粉堆積。目前研究發現，糖類的訊息傳遞可能與植物荷爾蒙離層酸有關。離層酸已知在植物生長發育上扮演重要角色，但其和澱粉代謝的關聯卻仍未清楚。本篇研究以阿拉伯芥(Arabidopsis thaliana)為材料，探討離層酸與糖類在植物生長發育及澱粉代謝上之交互作用。首先在不同濃度的糖類環境中，比較野生型阿拉伯芥的植株根長與葉片內澱粉堆積之情形，發現於高濃度糖類處理下的植株，其根長較未經糖類處理者短，且澱粉含量亦較高，得知高濃度糖類能抑制植物根部延長，並促進澱粉堆積。接著以離層酸處理植株並分析其根長與澱粉含量，發現以離層酸處理後，植株之根長較未經處理時短，而澱粉含量減少，顯示離層酸抑制根部生長，但促進澱粉水解；同時以高濃度糖類及離層酸處理時，發現植株根長較高濃度糖類單獨處理時長，且澱粉含量亦較低，顯示離層酸可回復由高濃度糖類所造成的生長抑制，並促進澱粉水解。接著以反轉錄聚合酶連鎖反應(RT-PCR, reverse transcription-PCR)偵測澱粉水解相關基因之表現情形，發現在離層酸處理下，SEX1(STARCH EXCESS 1)表現量明顯上升，顯示離層酸能誘導SEX1基因表現，促進澱粉水解。最後，比較離層酸對於澱粉堆積突變株體內澱粉含量的變化，發現sex1突變株中，離層酸無法促進澱粉水解，該結果顯示SEX1為離層酸促進澱粉水解所必需。綜合以上結果，得知離層酸與糖類在植物生長及澱粉水解上，扮演相拮抗之角色；離層酸藉由誘導SEX1的表現促進澱粉水解。

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