| Summary: | 碩士 === 國立中興大學 === 農業生物科技學研究所 === 85 === ABSTRACTPlant seeds store triacylglycerols in discrete
organelles called oil bodies. An oil body is surrounded by a
half-unit membrane of phospholipids and alkaline proteins termed
oleosins. Triacylglycerols and two oleosin isoforms of 17 and
15 kDa were exclusively accumulated in oil bodies of developing
sesame seeds. During seed development, oleosin 17 kDa emerged
later than oleosin 15 kDa, yet developed subsequently into the
most abundant protein in mature oil bodies.
Phosphotidylcholine, the major phospholipid in oil bodies, was
amassed in ER during the formation of oil bodies. The results
support that oil bodies originate from ER with actively
synthesized triacylglycerols and phosphotidylcholine whereas
oleosins target onto budding oil bodies directly without
packaging in ER. Prior to the formation of oil bodies, few oil
droplets of smaller size were observed in vivo and in vitro.
These oil droplets were unstable presumably due to the lack of
steric hindrance shielded by oleosins. The temporary
maintenance of these droplets as small entities seemed to be
provided by phospholipids wrapped in ER. Oil bodies assembled
in late developing stages possessed a higher ratio of oleosin 17
kDa over oleosin 15 kDa and were utilized earlier during
germination. It seems that the proportion of oleosin 17 kDa on
the surface of oil bodies is related to the priority of their
utilization.
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