Cyanogenesis in cassava
1993
Nambisan, M.
The distribution pattern of linamarin and its major catabolic enzymes - linamarase, hydroxinytrielyase (HNL) and B-cyanoalanine synthase (B-CAS) was studied in cassava tissues. In all cultivars studied higher accumulation of linamarin was observed in leaves, stem and rind tissues as compared to tuber. All three enzymes were present in cassava tissues, indicating active turnover of linamarin in the plant. The distribution of linamarin in tissues was found to vary in different growth stages. Studies on the metabolism of linamarin in early growth phases showed that during germination, almost all the linamarin present in stem was utilized. The levels remained unchanged initially till roots and leaves developed and then decreased rapidly. Partial translocation of linamarin to roots was observed. However, the presence of linamarase, HNL and B-CAS activity at all stages suggests partial mobilization and utilization of linamarin as noncyanogenic compounds. Total HCN potential decreased initially but later increased due to subsequent biosynthesis in leaves. Detailed studies on cassava linamarase indicate the role of certain inhibitors, which could prevent linamarase action, thereby facilitating transport of linamarin. These studies would throw light on further understanding the metabolism and mechanism of transport of linamarin in the plant, which is necessary for effective control of cyanogenesis in cassava.
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