NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Ab
scis
sio
n
1
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Abscission
• Definition: Separation of plant organs from the mother plant
• Problem: Loss of final product quality and yield in agriculture and horticulture
• Our Aim: Elucidate the mechanism of the abscission process to make an improved plant without abscission or with delayed abscission
• Main feature: Cell separation including breakdown of middle lamella accompanying modification of cell wall components
Figure 1. a, Premature abscission of poinsettia flower. b, Abscission zone (AZ) development in the induced abscission system. C, Longitudinal section of the AZ (stained with calcofluor)
a b c
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Ab
scis
sio
n
3
Why poinsettia? Why abscission? Why Minnesota?
Poinsettia is the most important potted plant in Norway
• 6 million plants produced every year
NGF (The Norwegian Grower’s Association) identified poinsettia as the main target for research, and specifed the areas
• Flower abscission
• Virus
• White fly
The Norwegian Reseach Council (NFR) funded a large Strategic Programme coordinated by Prof. Roar Moe from 2002-2005
NFR funded another project 2004-2007 (Reidunn Aalen, UiO)
Fulbright scholarship 2009-2010 to Trine H-E as a visiting scientist at UMN to work with Jerry D. Cohen and Gary Gardner at the Dept of Horticultural Sciences, UMN: two highly distinguished scientists in the auxin field
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Ab
scis
sio
n
4
Flowers of poinsettia
Flowers in the centre of the red bracts
3rd order flowers used in all experiments = 6 identical buds/star
From Rasolomanana 2008
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Ab
scis
sio
n
5
Induction of abscission
Decapitating the buds to intiate abscission
Initiated in 7 days under winter conditions (under low light)
98-100 % induction if done accurately
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Ab
scis
sio
n
6
Control Induced abscission Natural abscission
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
THE HORMONE STORY
Ab
scis
sio
n
7
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Ab
scis
sio
n
8
Decapitation must be accurate!
Cut position extremely important
Applications of
• IAA
• ABA
• GA3
• Ethylene
• Combinations of two
From Munster 2006
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Ab
scis
sio
n
9
Hormone interactions
Hypothesis based on experiments with 3 cut positions and applications of IAA, ABA, GA3
Mathiesen et al in prep
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
So I came to Minnesota…
Ab
scis
sio
n
11
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Auxin transport studies
Distribution of IAA in buds verified
Next step was to verify if the auxin protects the AZ from developing through auxin transport from the anthers and top of the bud to the AZ
N-(1-Naphtyl)Phthalamic acid (NPA) inhibits auxin transport
Ab
scis
sio
n
12
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
We decided it would be cool to analyze the whole plants:
Analyze whole plants of poinsettia to get IAA distribution of the whole plant, incl flowers – an IAA map of poinsettia
This is feasible because poinsettia is vegetatively propagated and has an early responsiveness to short days to induce flowering
Ab
scis
sio
n
13
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Plants analyzed: non-flowering, flowering and past anthesis (abscised)
Ab
scis
sio
n
14
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
The plants were carefully harvested and each piece (50-150 mg) was carefully labeled
Ab
scis
sio
n
15
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Acknowledgements
Thanks to Jerry and Gary for hosting me!
Thanks to Xing, Sumaira and Peng for helping out in the lab!
Thanks to the members of Jerry’s, Gary’s and Adrian’s groups for their help, friendship and support
Thanks to John Erwin for helping me aquire poinsettias
Thanks to Roger for the help in the greenhouses
Thanks to my husband Odd Arne for helping me with the statistics
Ab
scis
sio
n
16 Thanks to all of you!Thanks to Fulbright!
NO
RW
EG
IAN
UN
IVER
SIT
Y O
F LIF
E S
CIE
NC
ES
www.umb.no
Ab
scis
sio
n
17
THANK YOU FOR YOUR ATTENTION !