Engineering drought-tolerant crops plants

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Engineering drought-tolerant crops plants
Eduardo Blumwald Dept. of Plant
Sciences, University of California_at_Davis
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Observations (i) Salt and Drought stress
accelerate the senescence of plants. (ii) Stress
modifies Sink/source relationships.(iii)
Cytokinins delay leaf senescence.
Hypothesis In contrast to the common dogma that
senescence is a beneficial process to plants
during stress, it is possible to actually enhance
the tolerant of plants to drought if the
drought-induced senescence of leaves is delayed
during the drought episode.RationaleBased on
the assumption that senescence is a type of cell
death program that could be unnecessarily
activated in different plants during stress and
that suppressing it would enable plants to mount
a vigorous acclimation response
Strategy Regulated IPT expression by a
maturation- and stress-inducible promoter, could
maintain optimal levels of cytokinin levels
during stress, delaying stress-induced
senescence. IPT (isopentenyl transferase ) is
the limiting factor for cytokinin biosynthesis
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SARK
IPT
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Wild-type and transgenic plants expressing
PSARKIPT plants after 15 days drought
Treatment followed by 7 days re-watering.
Wild-type
PSARKIPT
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Oxidative Metabolism Conclusions
WT
hn
SOD
e-
O2
O2-
H2O2
PSII
CAT
PSI
AsA
GSH
NADP
H2O
NADP
GR
DHAR
APX
MDHAR
NADPH
GSSG
NADPH
DHA
MDHA
H2O
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Oxidative Metabolism Conclusions
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hn
SOD
e-
O2
O2-
H2O2
PSII
CAT
PSI
AsA
GSH
NADP
H2O
NADP
MDHAR
GR
DHAR
NADPH
GSSG
NADPH
DHA
MDHA
H2O
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A/Ci CURVES
CO2 assimilation rate µmol CO2.m-2s-1
CO2 assimilation rate µmol CO2.m-2s-1
Internal leaf CO2 (Pa)
Internal leaf CO2 (Pa)
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Photosyn Assistant Program to determine factors
limiting CO2 assimilation (Farquhar et al.,
(1980), Sharkey (1985), Harley and Sharkey (1991)
and Harley et al. (1992)
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CALVIN CYCLE
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PHOTORESPIRATION
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FIELD TRIALS Brawley (Imperial Valley, CA)
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Effect of restricted watering ( OWA) on yield of
WT plants
a
ab
b
FW g/plant
c
Treatment of OWA
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Effect of restricted watering ( OWA) on yield of
WT and pSARK-IPT plants
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FW g/plant
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WT
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T2-36
T4-24
Treatment of OWA
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Effect of restricted watering ( OWA) on yield of
WT and pSARK-IPT plants
DW g/plant
WT
T2-36
T4-24
Treatment of OWA
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Transgenic lines
Collaborations Cassava Willi Gruissem (ETH
Zurich) Cotton Hong Zhang (Texas Tech
Univ) Flowers Ryohei Nakano (Okayama
University, JAPAN) Alfalfa INTA (Castelar,
Argentina) Sugar cane Judy Zhu (Hawaii Ag.
Center)
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Dr. Rosa M. Rivero Ellen Tumimbang Rosa
Jauregui Dr. Lianhai Fu UC Davis Genome Center
Prof. Shimon Gepstein (Technion,Israel) Prof. Ron
Mittler (Univ. of Nevada_at_Reno) Prof. H.
Sakakibara (RIKEN, Tsurumi, Yokohama, Japan) Dr.
Ann Blechl (USDA, Albany, CA)