Question

The male component of gametophytic self-incompatibility exhibited by Nicotiana alatais an F-box protein that is part of an E3 ubiquitin ligase.  Based on information given in lecture and lecture notes, propose a model to explain how the F-box protein and the S-RNase mediate self-incompatibility.  Be sure to account for the action of the proteins in compatible and incompatible interactions.  

Answer 1

Self incompatibility is genetic coded measure to control breeding between same species. In Nicotiana alatois it is controlled by highly allelic S locus. If proteins from S locus in male matches with S locus expressed in Style it prevents the breeding. In Nicotiana alatois a Style specific extranuclear RNase and 10 proteins of F-box DD genes. F-box protein are competent of SCF complex takes ubiquitin from E2 ubiquitin conjugating enzyme and transport it to a target protein. F-box protein bind and ubiqutylate the S-RNase which causes degradation by proteosomic pathway and causes self incompatibility.