Proteome analysis of cultivar-specific interactions between Rhizobium leguminosarum biovar trifolii and subterranean clover cultivar Woogenellup

Proteome analysis was used to identify proteins that are involved in the ea rly stages of nodulation between the subterranean clover cultivar Woogenell up and the Rhizobium legominosarum by. trifolii strains ANU843 and ANU794. Strain ANU843 induces nitrogen-fixing nodules whereas strain ANU794 forms a berrant nodules on the roots of cv. Woogenellup that fail to develop beyond an early stage. Our aim was to identify proteins that might be involved in the early stages of nodulation over a 48 h period and to identify proteins that are differentially displayed during the interactions between the host and the two microbes. Proteome maps from control Woogenellup roots and ino culated roots were generated and compared at 24 and 48 h post inoculation. Over 1 500 spots were resolved on all gels. Of the 16 protein spats that we re differentally displayed or developmentally regulated, 10 were assigned p utative identities. These included an alpha -fucosidase, several ethylene-i nduced proteins, a Cu/Zn superoxide dismutase, a hypothetical 16.5 kDa prot ein, tubulin alpha -chain, chaperonin 21 precursor and triosephosphate isom erase. Of the 22 constitutively expressed proteins spots examined, eight sp ots were assigned putative protein homologies through N-terminal sequencing and included several pathogenesis and stress-related proteins. The result may suggest that ethylene levels are upregulated during the early stages of infection but that this does not result in the induction of common pathoge nesis-related proteins. The specific induction of alpha -fucosidase by ANU7 94 may be important in the nodulation failure phenotype of strain ANU794.