Abstract

Since the cereal endosperm is a dead tissue in the mature grain, beta-oxidation is not possible there. This raises the question about the use of the endosperm oil in cereal grains during germination. In this study, mobilization of lipids in different tissues of germinating oat grains was analysed using thin-layer and gas chromatography. The data imply that the oat endosperm oil [triacylglycerol (TAG)] is not a dead-end product as it was absorbed by the scutellum, either as free fatty acids (FFAs) released from TAG or as intact TAG immediately degraded to FFAs. These data were supported by light and transmission electron microscopy (LM and TEM) studies where close contact between endosperm lipid droplets and the scutellum was observed. The appearance of the fused oil in the oat endosperm changed into oil droplets during germination in areas close to the aleurone and the scutellar epithelium. However, according to the data obtained by TEM these oil droplets are unlikely to be oil bodies surrounded by oleosins. Accumulation of FFA pools in the embryo suggested further transport of FFAs from the scutellum. Noticeably high levels of TAG were also accumulated in the embryo but were not synthesized by re-esterification from imported FFAs. Comparison between two oat cultivars with different amounts of oil and starch in the endosperm suggests that an increased oil to starch ratio in oat grains does not significantly impact the germination process.

Keywords

Avena sativa; cereal; endosperm; germination; lipid mobilization; oat; oil bodies; scutellum; starch; triacylgycerol

Published in

Journal of Experimental Botany
2010, Volume: 61, number: 11, pages: 3089-3099
Publisher: OXFORD UNIV PRESS, GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND

SLU Authors

• Leonova, Svetlana

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

• Grimberg, Åsa

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

• Marttila, Salla

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    

• Stymne, Sten

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

• Carlsson, Anders

  • Department of Plant Breeding, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Agricultural Science


Publication identifier

DOI: https://doi.org/10.1093/jxb/erq141

Permanent link to this page (URI)

https://res.slu.se/id/publ/30277