Regulation of Sucrose Phosphate Synthase of the Sweet Potato Callus is Related to Illumination and Osmotic Stress

甘藷癒創組織中蔗糖磷酯合成酶受光及滲透逆境之調控

李木和(Mu-Ho Lee) ； 楊健志(Chien-Chi Yang) ； 王恆隆(Heng-Long Wang) ； 李平篤(Ping-Du Lee)

《Botanical Bulletin of Academia Sinica》 44卷4期 (2003/10) Pp. 257-265

https://doi.org/10.7016/BBAS.200310.0257

摘要

將甘藷塊根癒創組織（cellus）經光照、黑暗與滲透逆境處理後，並分別純化出蔗糖磷酯合成酶（SPS）與蔗糖合成酶（SS）做比較。在SPS之生化性質方面：光照處理下所得之SPS，其最適反應pH值為7.5，最適反應溫度為37℃，在SPS之間酵素活性穩定，酵素本身亦會受到Glc 6-P的促進及Pi的抑制調控。然而經由滲透逆境處理後所得SPS，不受Glc 6-P及Pi的異位調控。另外，光照處理所得的SPS與SS最大活性及最多蛋白質含量均出現在培養第14天，但在高滲透逆境下SPS則以第7天的活性為最高；而SS仍維持第14天有最大活性。黑暗生長下之癒創組織SPS活性均很低，但SS仍有相當的活性。以組織切片及原位組織雜交技術來分析，發現高滲透逆境下均有大量的澱粉粒累積，且光照與滲透逆境處理，可促進甘藷癒創組織內 SPSmRNA生成量。配合電泳分析及酵素純化結果，推測在光照與高滲透逆境有助於SPS基因的表現及酵素活性的增加，或有可能誘導產生不同的SPS及SS異構酶，以便在甘藷塊根癒創組織生長中表現不同的生理活性。

關鍵字

黑暗 ； 光照 ； 滲透逆境 ； 蔗糖磷酯合成酶 ； 蔗糖合成酶 ； 甘藷癒創組織

並列摘要

Sucrose phosphate synthase (SPS) was purified from sweet potato callus grown under different conditions, including illumination, darkness, and osmotic stress. The properties of the enzymes purified from the different conditions were compared. Since sucrose synthase (SS) could also be purified using the purification process, the expression patterns and properties of the two enzymes were also compared. The SPS purified from the calli tissue medium under illumination had an optimum pH of 7.5. The enzyme had an optimum reaction temperature of 37°C, and maintained stable activity at pH 6 to 8. It was allosterically regulated using either Glc 6-P or Pi. However, the enzyme purified from the tissues grown under osmotic stress conditions was not allosterically regulated using Glc 6-P or Pi. The maximal activity of SPS and maximal protein content of the illumination grown calli appeared on the 14th day after the culture was transferred into a new medium. This was compared with the peak value on the 7th day for the samples under osmotic stress. The maximum activity for SS was observed on the 14th day. The dark grown cells had very low SPS, but normal SS activities. A histological study revealed an abundance of starch granules in the osmotic stressed cells. The in situ hybridization technique showed that the illumination and osmotic stress conditions induced the accumulation of SPS mRNA. The PAGE and enzyme activity assay data showed that, in addition to enhancing SPS gene expression, the activation of SS gene expression isozymes may be achieved under the illumination and osmotic stress conditions.

並列關鍵字

Dark ； Illumination ； Osmotic stress ； Sucrose phosphate synthase ； Sucrose synthase ； Sweet potato callus