Premium
Presence of β‐cyanoalanine synthase in unimbibed dry seeds and its activation by ethylene during pre‐germination
Author(s) -
Hasegawa Ryo,
Tada Tomoko,
Torii Yuichiro,
Esashi Yohji
Publication year - 1994
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1994.tb00411.x
Subject(s) - radicle , germination , xanthium , imbibition , ethylene , botany , chemistry , oryza sativa , biology , glycine , agronomy , biochemistry , amino acid , gene , catalysis
Evolution of HCN from both rice ( Oryza sativa ) and cocklebur ( Xanthium pennsylvanicum ) seeds increased during a pre‐germination period and preceded the evolution of (C 2 H 4 ). These two species were adopted as the representatives of starchy and fatty seeds, respectively. Ethylene promotes seed germination of many species. However, HCN evolution declined abruptly when the radicles emerged and before the peak in C 2 H 4 evolution. More‐over, both rice and soybean ( Glycine max ) seeds showed some activity of β‐cyanoalanine synthase (CAS, EC 4.4.1.9) even in the unimbibed dry state. The activities of CAS in the lower seed of cocklebur and in soybean seeds increased rapidly after emergence of the radicle. However, the CAS of rice seeds, with high activity in the dry state, exhibited a bimodal change, gradually decreasing until radicle emergence had occurred, but then increaing. It is thus likly that HCN evolution during initial imbibition may be derived from cyanogenic reserves and controlled by both pre‐existing and subsequently‐developing CAS. The exogenous application of C 2 H 4 stimulated the activities of CAS in both rice and upper cocklebur seeds and reduced their cyanogen contents. Therefore, the decline of HCN evolution after germination seems to be due to the increased activities of CAS by endogenously produced C 2 H 4 .