Characterisation and functional analysis of two barley caleosins expressed during barley caryopsis development.
Two full-length cDNA sequences homologous to caleosin, a seed-storage oil-body protein from sesame, were identified from a series of barley grain development cDNA libraries and further characterised. The cDNAs, subsequently termed HvClo1 and HvClo2, encode proteins of 34 kDa and 28 kDa, respectively. Real-time RT-PCR indicated that HvClo1 is expressed abundantly during the later stages of embryogenesis and is seed-specific, accumulating in the scutellum of mature embryos. HvClo2 is expressed mainly in the endosperm tissues of the developing grain. We show that HvClo1 and HvClo2 are paralogs that co-segregate on barley chromosome 2HL. Transient expression of HvClo1 in lipid storage and non-storage cells of barley using biolistic particle bombardment indicates that caleosins have different subcellular locations from the structural oil-body protein oleosin, and by inference participate in different sorting pathways. We observe that caleosin sorts via small vesicles, suggesting a likely association with lipid trafficking, membrane expansion and oil-body biogenesis.
Liu
Hui
H
Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, Scotland, UK.
Hedley
Peter
P
Cardle
Linda
L
Wright
Kathryn M
KM
Hein
Ingo
I
Marshall
David
D
Waugh
Robbie
R
D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000254:growth & development / Q000378:metabolism*; D050356:Lipid Metabolism; D010940:Plant Proteins / Q000096:biosynthesis*; D012639:Seeds / Q000378:metabolism
D002135:Calcium-Binding Proteins; D010940:Plant Proteins; C402836:caleosin protein, Sesamum indicum