Kojima M, Iwatsuki N, Data E S, Villegas C D, Uritani I
Faculty of Agriculture, Nagoya University, Chikusa, Nagoya 464, Japan.
Plant Physiol. 1983 May;72(1):186-9. doi: 10.1104/pp.72.1.186.
When cassava (Manihot esculenta Crantz) root was cut into blocks and incubated under laboratory conditions, the blocks showed more widespread and more even symptoms of physiological deterioration than those under natural conditions. Thus, the tissue block system has potential for biochemical studies of natural deterioration of cassava root. The changes in cyanide content and linamarase (linamarin beta-d-glucoside glucohydrolase; EC 3.2.1.21) activity in various tissues during physiological deterioration were investigated. Total cyanide content increased in all parts of block tissue after 3-day incubation. The degree of increase in cyanide was most pronounced in white parenchymal tissue, 2 to 3 millimeters thick, next to the cortex (A-part tissue), where no physiological symptoms appeared. On the other hand, linamarase activity was decreased in all parts of block tissue after a 3-day incubation. A time course analysis of A-part tissue indicated a clear reciprocal relationship between changes in total cyanide and linamarase activity; total cyanide increased, while linamarase activity decreased. Free cyanide constituted a very small portion of the total cyanide and did not change markedly.
将木薯（Manihot esculenta Crantz）块根切成块状并在实验室条件下培养时，这些块根表现出比在自然条件下更广泛、更均匀的生理劣化症状。因此，组织块系统在木薯根自然劣化的生化研究方面具有潜力。研究了生理劣化过程中不同组织中氰化物含量和亚麻苦苷酶（亚麻苦苷β - d - 葡萄糖苷葡糖水解酶；EC 3.2.1.21）活性的变化。培养3天后，块根组织各部分的总氰化物含量均有所增加。氰化物增加程度最明显的是紧邻皮层的2至3毫米厚的白色薄壁组织（A部分组织），此处未出现生理症状。另一方面，培养3天后，块根组织各部分的亚麻苦苷酶活性均下降。对A部分组织的时间进程分析表明，总氰化物变化与亚麻苦苷酶活性之间存在明显的反比关系；总氰化物增加，而亚麻苦苷酶活性下降。游离氰化物在总氰化物中所占比例非常小，且没有明显变化。
