1997, Inhibiiors of ethylene responses in piants at the receptor level: Recent developments. -Physiok Plant, UKf: 577-582.. A number of organic molecules that appear to block the ethylene receptor have been discovered recently. For example, on irradiation with visible lighl. diazocyclopentadiene (DACPK gives rise to some potent but as yet unidentified inhibitor eompounds. Some synthetic cyclopropenes have been shown io bind to the ethylene receptor and prevent the physiological action of"ethyiene for extended periods. Cydopropene iCPi. 1-methylcyclopropene (1-MCPi and 3.3-dimethyIcyclopropene (3.3-DMCPi have been shown to prevent ethylene effects in a number of plants. As low a concentration as (1.5 nl I ' of k.MCP is sufficient lo protect carnation fDianthus caryophyttusi flowers for several davs against ethylene. and 0.7 nl Y' 1-MCP or CP will prevent the ripening of banana iMusa sapieniumi lor 12 days at 24°C, Some plant organs require higher concentrations of these inhibitors. Complete inhibition of ethyiene effects in pea seedlings requires treatment w iih 40 nl I ot 1 -MCP, These nov el inhibitors appear lo be suitable for many commercial applications inciuding extending the xase life of cut flowers and the display life of potted plants. Since l-.MCP apparentlv is non-toxic at concentrations that are active, it mav in fnture be available for regulating Ihe ripening of tniits and preventing the deleterious effect.s of ethylene in v egetables,

Ethylene perception in Arabidopsis is controlled by a family of five genes, including ETR1, ERS1 (ethylene response sensor 1), ERS2, ETR2, and EIN4. ERS1, the most highly conserved gene with ETR1, encodes a protein with 67% identity to ETR1. To clarify the role of ERS1 in ethylene sensing, we biochemically characterized the ERS1 protein by heterologous expression in yeast. ERS1, like ETR1, forms a membrane-associated, disulfide-linked dimer. In addition, yeast expressing the ERS1 protein contains ethylene-binding sites, indicating ERS1 is also an ethylene-binding protein. This finding supports previous genetic evidence that isoforms of ETR1 also function in plants as ethylene receptors. Further, we used the ethylene antagonist 1-methylcyclopropene (1-MCP) to characterize the ethylene-binding sites of ERS1 and ETR1. We found 1-MCP to be both a potent inhibitor of the ethylene-induced seedling triple response, as well as ethylene binding by yeast expressing ETR1 and ERS1. Yeast expressing ETR1 and ERS1 showed nearly identical sensitivity to 1-MCP, suggesting that the ethylene-binding sites of ETR1 and ERS1 have similar affinities for ethylene.

No abstract

No abstract

No abstract