The effects of the plant growth regulator ethylene, and of ethylene inhibitors, on barley (Hordeum vulgate L.) Germination and seedling growth were investigated. Exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) at 100 µM enhanced ethylene production by barley seedlings and stimulated shoot growth, whereas both germination and seedling growth were inhibited by antagonists of ethylene perception (75 µM silver ions, 100 µM 2,5-norbornadiene (NBD)). In contrast, germination was unaffected by, and root and shoot growth of seedlings was strongly stimulated by inhibitors of ethylene biosynthesis (10 µM cobalt chloride, 10 µM aminoethoxyvinylglycine (AVG)). Since the ethylene and polyamine biosynthetic pathways are linked through S-adenosylmethionine, this prompted further explorations into the role of polyamines in germination and seedling growth. Exogenous polyamines (putrescine, spermidine and spermine) at 1 µM concentration stimulated barley seedling growth in a similar fashion to the ethylene biosynthetic inhibitors. Both polyamines and ethylene biosynthetic inhibitors reversed the inhibitory effects of ethylene perception inhibitors on germination and seedling growth. Blocking endogenous ethylene production with aminoethoxyvinylglycine enhanced the free putrescine and spermidine content of germinating barley grains. Thus endogenous polyamines may play a complementary, growthpromotive, role to ethylene in the normal course of barley germination. Further, experiments that have been carried out using inhibitors of ethylene biosynthesis may have to be re-evaluated to take the possible effect of polyamines into account.
|Number of pages||7|
|Journal||Journal of experimental botany|
|Publication status||Published - 2000|
- Hordeum vulgare