Petr GALUSZKA Centre of the Region Haná for Biotechnological and Agricultural Research Palacký...
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Petr GALUSZKA Petr GALUSZKA Centre of the Region Haná for Biotechnological and Agricultural Research Palacký University in Olomouc FROM CYTOKININ METABOLISM TO FROM CYTOKININ METABOLISM TO AGRICULTURE AGRICULTURE
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CK qualitative analysis during maize development pmol/g of leaf fresh weight kernel germination shoot developmentroot development 20th day 20th day isopentenyladenine trans-zeatin cis-zeatin dihydrozeatin
Transcript of Petr GALUSZKA Centre of the Region Haná for Biotechnological and Agricultural Research Palacký...
Petr GALUSZKAPetr GALUSZKACentre of the Region Haná for
Biotechnological and Agricultural Research Palacký
University in Olomouc
FROM CYTOKININ METABOLISM TO FROM CYTOKININ METABOLISM TO AGRICULTUREAGRICULTURE
Gajdošová et al., JXB 2011
CK qualitative content analysisbarley maize CK-type Arabidop
sispmol/g of leaf fresh weight
15.1 2.1 iP 22.236.4 1.4 tZ 60.5
206.7 164.3 cZ 17.57.5 1.7 DHZ 4.2
0
20
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100
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CK qualitative analysis during maize developmentpm
ol/g of leaf fresh weight
kernelgerminationshoot developmentroot development20th
day20thday
isopentenyladenine trans-zeatin cis-zeatin dihydrozeatin
CYTOKININ SENSING in Zea maysHistidine kinase – CK receptor bound to membranes
Apparent KD (nM)CK ZmHK
1ZmHK
2ZmHK3
isopentenyladenine
2.3 0.6 2.7
trans-zeatin 24 0.4 7.2cis-zeatin 26 8.4 21dihydrozeatin 630 2 232tZR 3000 70 280iPR not detectable 400tZOG not detectable
S. Lomin et al., JXB 2011
Contrary to Arabidopsis receptors, there is higher
sensitivity to cZ and DHZ at least on some maize receptors
N
N
NH
CH3
CH3N
NH
N
N
NH
CH3
N
NH
OH
N
N
NH CH3N
NH
OHN
N
NHN
NH
CH3
OH
N
N
NHN
NH
CH2
CH3
iP
?
cZ
DHZ
tZ
zeatin metabolism in planta is rather obscure
de novo biosynthesis tRNA
degradation
CYP450
zeatinisomerase
IPTLOG
zeatinreductase
?
proved in plantagene is knownproved in vitroactivity detectedhypothesized
Cytokinin dehydrogenases have different preferences
CKX iP tZ cZ DHZ
AtCKX1 100
72 116
0
AtCKX2 100
78 2 0
AtCKX3 100
20 0 0
AtCKX4 100
89 4 0
AtCKX5 100
68 68 0
AtCKX6 100
13 37 0
AtCKX7 100
30 116
0
ZmCKX1 100
122
138
0
ZmCKX10
100
154
165
0
HvCKX2 100
190
0 0
CKX relative activity CKX gene families:Arabidopsis thaliana 7 genesZea mays 13 genesOryza sativa 11 genesHordeum vulgare 11 genes
CKX as a transgene
Constitutive overexpression of CKX causes cytokinin-deficient phenotype
Main function of CKs on plant differentiation proved together with opposite role on root and shoot development
Cytokinin content
30–50% of WT
Construct: 35S::HvCKX2
pmol/g fresh w
CK WT HvCKX2
seedlingsiP 115.8 31.5tZ 21.7 10.4
Transformation of Barley with CKX genes
Ubiqutin::ZmCKX1
Ubiqutin::HvCKX2
WT trsg WT Z2 Z4 Z7 Z8 Z10
WTZ10
Constitutive CKX overexpression in cereal:prematured senescenceno onset of flowering (sterility)enlarged root system (dependent of transgene)
pmol/g fresh w
CK WT trsgroot
iP 22.2 16.1tZ 87.3 122cZ 42.8 188DHZ
2.8 7.5
shootiP 14.0 10.8tZ 37.6 12.2cZ 161 101DHZ
2.6 2.9
CKX and IPT gene families in barley11 CKX genes 2 tRNA IPT genes 5 de novo
IPT genes
wild type situation our transgenic approach
