Institute of Biological Chemistry and Biochemistry/Biophysics Program, Washington State University, Pullman, Washington 99164-6340.
Plant Physiol. 1986 Jan;80(1):68-71. doi: 10.1104/pp.80.1.68.
Suspension-cultured cells of tomato accumulate proteinase Inhibitor I as the sucrose is depleted from 1% to less than 0.1% in the culture medium. Inhibitor I can be prematurely induced to accumulate in the cells by the addition to the medium of the proteinase inhibitor inducing factor, trigalacturonic acid, ethylene glycol chitin, or chitosan. In cultures grown in 0.6% initial sucrose with no inducers added, a uronic acid-rich extracellular polysaccharide appears in the medium during growth of the cells. This extracellular polysaccharide apparently contains an ;endogenous inducer' of Inhibitor I synthesis. When the partially purified polysaccharide is added to the culture medium, Inhibitor I accumulation is induced. Proteinase inhibitors also accumulate in tobacco and alfalfa suspension-cultured cells as the cell cultures age. As with the tomato cultures, a uronic acid-rich component(s) appears in the media prior to inhibitor accumulation. These data suggest that an endogenous inducer may be activating proteinase inhibitor genes through a similar mechanism in all three types of cells.
悬浮培养的番茄细胞在培养基中蔗糖耗尽从 1%降至 0.1%以下时会积累蛋白酶抑制剂 I。通过在培养基中添加蛋白酶抑制剂诱导因子、三半乳糖醛酸、乙二醇壳聚糖或壳聚糖，可以提前诱导抑制剂 I 在细胞中积累。在初始蔗糖为 0.6%且未添加诱导剂的培养物中，细胞生长过程中培养基中会出现一种富含糖醛酸的细胞外多糖。这种细胞外多糖显然含有蛋白酶抑制剂 I 合成的“内源性诱导剂”。当将部分纯化的多糖添加到培养基中时，会诱导抑制剂 I 的积累。随着烟草和苜蓿悬浮培养细胞的衰老，蛋白酶抑制剂也会在其中积累。与番茄培养物一样，在抑制剂积累之前，富含糖醛酸的成分（多个）会出现在培养基中。这些数据表明，内源性诱导剂可能通过类似的机制在所有三种类型的细胞中激活蛋白酶抑制剂基因。
