摘要
酶法分离的菠菜(Spinacla oleracea L.)叶肉细胞,经光合 CO_2固定预处理后转入无CO_2反应介质中,光下光合固定碳素损耗严重,其速率明显高于暗中,并受到提高光强及增加氧气浓度的明显促进,以及光合电子传递抑制剂 DCMU、解偶联剂 NH_4c1的显著抑制。外源乙醇酸可在一定程度上缓减光下光合固定碳素的损耗,但对暗中的影响不大。双离子交换层析分析表明,光下及暗中淀粉均迅速降解,且光下淀粉降解稍快。但光、暗淀粉降解过程中,可溶性碳素含量变化差异显著。光下淀粉降解并不伴随可溶性碳水化合物(3-磷酸甘油酸、磷酸三糖、蔗糖等)含量的相应增加,而暗中却可导致蔗糖及其它可溶性成分的显著积累。表明无 CO_2体系中,光下与暗中淀粉降解产物的代谢途径不同,其各自的生理作用也有明显差异。
Isolated spinach (spinacia oleracea L.) mesophyll cells, after being preilluminated for 40 rain for storage photosynthates loading (~14C), were shifted into CO_2-free mixture for investiga- tion of storage photosynthates degradation and its regulatory factors. The loss of fixed carbon (~14c) after 30 rain incubation in CO_2-free mixture in light was about 20%, which was much higher than that in dark (about 4.5%). The loss of fixed carbon was apparently stimulated by the increase of light intensity or O_2 concentration and depressed by DCMU or NH_4Cl. Moreover, ~he loss of fixed carbon, especially the soluble fraction, was reduced by the addition of glyco- late in light but not in dark. The obvious degradation of starch in spinach mesophyll cells in CO_2-free system was monitored both in light and in dark. Unlike in dark, starch degradatign in light was riot associated with a detectable accumulation of the soluble products (PGA, Ribulose— 5-phosphate, sucrose etc.). Based on the above results, the different metabolic patterns for the products of starch degradation in light and in dark were discussed and ahe possible physiological roles were also proposed.
基金
江苏省教委自然科学基金资助项目
关键词
菠菜
无CO2体系
光合产物降解
Spinacia oleracea
Mesophyll ceils
CO_2-free mixture
Photosynthetic ener-gy stress
Degradation of storage photosynthates
