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A role for caleosin in degradation of oil‐body storage lipid during seed germination
Author(s) -
Poxleitner Marianne,
Rogers Sally W.,
Lacey Samuels A.,
Browse John,
Rogers John C.
Publication year - 2006
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2006.02845.x
Subject(s) - vacuole , germination , mutant , internalization , microbiology and biotechnology , wild type , storage protein , biology , biochemistry , chemistry , biophysics , botany , cell , cytoplasm , gene
Summary Caleosin is a Ca 2+ ‐binding oil‐body surface protein. To assess its role in the degradation of oil‐bodies, two independent insertion mutants lacking caleosin were studied. Both mutants demonstrated significant delay of breakdown of the 20:1 storage lipid at 48 and 60 h of germination. Additionally, although germination rates for seeds were not affected by the mutations, mutant seedlings grew more slowly than wild type when measured at 48 h of germination, a defect that was corrected with continued growth for 72 and 96 h in the light. After 48 h of germination, wild‐type central vacuoles had smooth contours and demonstrated internalization of oil bodies and of membrane containing α ‐ and δ ‐tonoplast intrinsic proteins (TIPs), markers for protein storage vacuoles. In contrast, mutant central vacuoles had distorted limiting membranes displaying domains with clumps of the two TIPs, and they contained fewer oil bodies. Thus, during germination caleosin plays a role in the degradation of storage lipid in oil bodies. Its role involves both the normal modification of storage vacuole membrane and the interaction of oil bodies with vacuoles. The results indicate that interaction of oil bodies with vacuoles is one mechanism that contributes to the degradation of storage lipid.