Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
Oil in oats
-some molecular insights
(Photo Å. Grimberg)
Anders S. Carlsson, SLU
Oat has high oil content
(Liu, Journal of Food Science, 2011)
(Photo Å. Grimberg)
Oat is unusual among the cereals
Fig. Oat grains at different
developmental stages
Lipid composition in
wild species of oat
(Leonova et al., Journ. of Agriculture and Food Chemistry, 2008)
Oat lines with up to 18% oil
(Peterson and Wood, Journal of Cereal Science, 1997)
6 8 10 12 14 16 18
Oil (%)
• Highest oil content among
the cereals
• Lines with up to 18% oil
by grain weight
• Increased oil was
negatively corr to starch
content
• Increased oil content was
positively corr to protein
and β-glucan content
Screening for oil quality in
cultivated oat
Oleic acid ranged from 31-40% in different cultivars
(Leonova et al., Journ. of Agriculture and Food Chemistry, 2008)
Oat oil is flavoured with with a
dash of unusual fatty acids
Increased oil content in the endosperm of cereals would be neccessary to make them
high-yielding oil crops, since the endosperm makes out the major part of the seed.
Endosperm in cereal grains
Oil localization in oat grains
Oat cultivars Freja (6% oil) and Matilda (10% oil) from Lantmännen Seed. The
difference in oil content was due to more oil in the endosperm in mature seeds.
(Banas et al., Journ Exp Bot, 2007)
(Heneen et al.,Plant Signalling and behaviour, 2009)
Light microscopy; E; Embryo, A; Aleurone, SA; SubAleurone, S; Starch, * Fused oil.
Small arrowheads; protein
Localization of oil in oat grains
Mobilization of lipid reserves in
germinating oat grains
(Leonova et al., Journ of Exp Bot, 2010)
Oat grains showing growth of the embryo and scutellum (S) after days (d) of
germination. The contour of the scutellum can be seen under the pericarp (see
arrow in b) and in the longitudinal cut of the seed (see arrows in e).
S
S S
0d 1d 2d
4d 7d 10d
c. 1st day after imbibition
g. 4th day after imbibition
(Leonova et al., Journ of Exp Bot, 2010)
Mobilization of lipid reserves in
germinating oat grains
After 4 day,scutellar epithelium (SE) cells
have elongated into the endosperm (ES)
and have come in close contact with oil
(black arrows) in the ES. Accumulation of
lipids (white arrows) are shown in the
SE.
At 1st day after imbibition, the scutellum
epithelium cells (SE) are tightly pressed
to each other and to the parenchyma
cells (SP)
All oil (TAG) was remobilized
during germination in both
cultivars
Degradation products (free
fatty acids, FFA) were taken
up by the scutellum
(Leonova et al., Journ of Exp Bot, 2010)
Mobilization of lipid reserves in
germinating oat grains
Comparative transcriptome and
metabolome study of
medium- and high-oil oat
454 sequencing of high-oil cv. Matilda endsoperm was used to develop
probes for a microarray that were hybridized with endosperm RNA from
medium-oil cv. Freja (6% oil) and Matilda (10% oil) at different
developmental stages.
(Hayden et al., The Plant Journal, 2011)
Transcript and metabolite data-
central carbon metabolism
(Hayden et al., The Plant Journal, 2011)
Comparative transcriptome and
metabolome study
• In general: Transcript levels of genes in central carbon metabolism/oil
biosynthesis were very similar but metabolite levels were very different,
between cultivars
• The high-oil cv. Matilda had much lower metabolites in glycolysis, as
well as cofactors (ATP, NADPH) needed for oil biosynthesis, comp to
medium-oil cv. Freja
• Some gene transcripts coding for starch synthesizing enzymes
(AGPase) differed between cultivars, suggesting that high oil content
might be caused by low starch synthesizing capacity
• A homolog to the transcription factor WRINKLED1 in Arabidopsis
(known to influence oil content of seeds) was found to be highly
expressed in both oat cultivars
(Hayden et al., The Plant Journal, 2011)
Carbon allocation in plant
storage tissues
Oat is very interesting to use as a model species for oil accumulation in the
cereal endosperm.
Characterization of oil
accumulation in model plant
storage tissues
7 dagar
35 dagar 42 dagar
15 dagar
StStäärkelserkelse
OljaOljaOljaOlja
StStäärkelserkelseStStäärkelserkelse
StStäärkelserkelseStStäärkelserkelseStStäärkelserkelseStStäärkelserkelse
OljaOljaOljaOlja
OljaOljaOljaOlja
OljaOlja
Jordmandel Jordmandel –– en modellven modellvääxt att omvandla xt att omvandla
sockerbeta och kassava till oljevsockerbeta och kassava till oljevääxterxter
Oat grain
endosperm
(Avena sativa)
Nutsedge tuber
parenchyma
(Cyperus
esculentus)
Aspen stem
(Populus
trichocarpa)
(Heneen et al., 2009, Turesson et al., 2010, Salla Marttila, unpublished 2013)
Nicotiana benthamiana
(tobacco) system
Agrobacterium mediated transient transformation of leaves, gives
transient gene expression. Fast system for characterizing genes.
(Method: Voinnet et al., 2003, Wood et al., 2009)
Quantification of fatty acids in TAG (triacylglycerol; oil) using
gas chromatography of fatty acid methyl esters. Highest oil in
leaves with oat WRINKLED1
Oil analyses of leaves expressing
WRINKLED1 homologs
(Grimberg et al., 2015)
Transcriptome analyses of
leaves expressing WRINKLED1
Summary
• Oats accumulate high amount of oil in
the grain
• This is due to an unusual capacity in
oats to accumulate a high proportion of
the oil in the endosperm.
• Oat oil contain a significant proportion of
polar lipids
• The oat endosperm oil is devoid (almost)
of oil bodies but our result indicate that
this oil proportion is still available as an
energy resource for the embryo during
germination
• Work towards ”high-oil” oat cultivars
focus on understanding mechanism
behind accumulation of endosperm oil.
Photo. Å. Grimberg
Theoretical oil yields of oil-oat
Rape seed (B. napus)
Seed yield: 2.5 tonnes/ha
Oil conc: 45%
Oil yield: 1.1 tonnes/ha
Oat (A. sativa)
Seed yield: 5 tonnes/ha
Oil conc: 5%
Starch conc: 60%
Oil yield: 0.25 tonnes/ha
Rape seed (B. napus)
Seed yield: 2.5 tonnes/ha
Oil conc: 45%
Oil yield: 1.1 tonnes/ha
Oat (A. sativa)
Seed yield: 3.9 tonnes/ha
Oil conc: 29%
Starch conc: 20%
Oil yield: 1.1 tonnes/ha High-oil oat
Theoretical oil yields of oil-oat
Aknowledgements
Åsa Grimberg, SLU
Svetlana Leonova, LU
Sten Stymne, SLU
Antoni Banas, Un. of Gdansk
Daniel Hayden, UC Davis
Katie Dehesh, UC Davis
Salla Marttila, SLU
Waheeb Heneen, SLU
Lantmännen Seed
• Swedish Research Council for
Environment, Agricultural
Sciences, and Spatial Planning
(Formas)
• TC4F Trees and crops for the
future (VINNOVA)
• SLU-LTJ strategic funds
• SSF Oil Crops for the Future
Photo. Å. Grimberg
Thank You