Flores H E, Galston A W
ARCO Plant Cell Research Institute, Dublin, California 94568.
Plant Physiol. 1984 May;75(1):110-3. doi: 10.1104/pp.75.1.110.
Arginine decarboxylase activity increases 2- to 3-fold in osmotically stressed oat leaves in both light and dark, but putrescine accumulation in the dark is only one-third to one-half of that in light-stressed leaves. If arginine or ornithine are supplied to dark-stressed leaves, putrescine rises to levels comparable to those obtained by incubation under light. Thus, precursor amino acid availability is limiting to the stress response. Amino acid levels change rapidly upon osmotic treatment; notably, glutamic acid decreases with a corresponding rise in glutamine. Difluoromethylarginine (0.01-0.1 millimolar), the enzyme-activated irreversible inhibitor of arginine decarboxylase, prevents the stress-induced putrescine rise, as well as the incorporation of label from [(14)C]arginine, with the expected accumulation of free arginine, but has no effect on the rest of the amino acid pool. The use of specific inhibitors such as alpha-difluoromethylarginine is suggested as probes for the physiological significance of stress responses by plant cells.
在渗透胁迫下的燕麦叶片中，无论光照还是黑暗条件下，精氨酸脱羧酶活性均增加2至3倍，但黑暗中腐胺的积累量仅为光照胁迫叶片的三分之一至二分之一。如果向黑暗胁迫的叶片供应精氨酸或鸟氨酸，腐胺含量会升至与光照处理相当的水平。因此，前体氨基酸的可利用性限制了应激反应。渗透处理后氨基酸水平迅速变化；值得注意的是，谷氨酸减少，谷氨酰胺相应增加。二氟甲基精氨酸（0.01 - 0.1毫摩尔），一种精氨酸脱羧酶的酶激活不可逆抑制剂，可阻止胁迫诱导的腐胺增加以及[(14)C]精氨酸的标记掺入，同时预期游离精氨酸会积累，但对其余氨基酸库没有影响。建议使用诸如α - 二氟甲基精氨酸等特异性抑制剂作为探究植物细胞应激反应生理意义的探针。
