Macromolecular composition of phloem exudate from white XXXX (Lupinus albus L.).

@entity2228 @entity535 @entity26 @entity2041 @entity1853 @entity460 @entity15 @entity3151 @entity16413 @entity9050 @entity1786
BACKGROUND: Members of the legume genus Lupinus exude phloem 'spontaneously' from incisions made to the vasculature. This feature was exploited to document macromolecules present in exudate of white @entity16413 (Lupinus albus [L.] cv Kiev mutant), in particular to identify proteins and RNA molecules, including microRNA (miRNA). RESULTS: Proteomic analysis tentatively identified 86 proteins from 130 spots collected from 2D gels analysed by partial @entity535 sequence determination using @entity15 / @entity15 . Analysis of a cDNA library constructed from exudate identified 609 unique transcripts. Both proteins and transcripts were classified into functional groups. The largest group of proteins comprised those involved in metabolism (24%), followed by protein modification/turnover (9%), redox regulation (8%), cell structural components (6%), stress and defence response (6%) with fewer in other groups. More prominent proteins were cyclophilin, ubiquitin, a @entity2228 -rich RNA-binding protein, a group of proteins that comprise a @entity2041 / @entity9050 -based mechanism to scavenge @entity26 radicals, enzymes of glycolysis and other metabolism including @entity1853 and @entity1786 synthesis. Potential signalling macromolecules such as transcripts encoding proteins mediating @entity460 level and the Flowering locus T (FT) protein were also identified. From around 330 small RNA clones (18-25 nt) 12 were identified as probable miRNAs by homology with those from other species. miRNA composition of exudate varied with site of collection (e.g. upward versus downward translocation streams) and nutrition (e.g. @entity3151 level). CONCLUSIONS: This is the first inventory of macromolecule composition of phloem exudate from a species in the Fabaceae, providing a basis to identify systemic signalling macromolecules with potential roles in regulating development, growth and stress response of legumes.
