Transcript valve margin

Patterning the Arabidopsis fruit
Arabidopsis fruit structure
valve
margin
valve
replum
Arabidopsis fruit opening
valve
margin
valve
replum
seed
Fruit dehiscence promotes seed dispersal
valve
valve
Genes involved in seed dispersal in
Arabidopsis can control loss of yield in
oilseed crops
Note that DZ = Valve Margin
Genes Controlling Fruit Development
?
?
?
replum
valve
valve
margin
SHATTERPROOF (SHP) gene is required
for valve margin formation
wild type
shp
Genes Controlling Fruit Development
?
SHP
?
replum
valve
valve
margin
IND and SHP are required for
valve margin formation
wild type
ind
shp
IND is expressed in stripes at the valve margin
and is positively regulated by SHP
valve margin
replum
wild type
valve
shp
Genes Controlling Fruit Development
SHP
?
IND
?
replum
valve
valve
margin
How is SHP and IND expression
limited to the valve margin?
SHP
IND
?
?
replum
valve
valve
margin
FRUITFULL (FUL) transcription factor is
required for valve cells
Valve cells
wild type
wild ful
type
ful
FUL is expressed
in valve cells
SHP and IND are ectopically
expressed in ful mutant valves
valve
Wild
type
valve
ful
mutant
IND expression
SHP and IND are negatively regulated
by FUL in the valves
Wild
type
ful
mutant
IND expression
Is the fruitfull mutant phenotype
caused by ectopic expression of the
valve margin (SHP, IND) genes?
The failure of ful-mutant fruit to elongate is
restored by mutations in shp and ind
Wild type
shp ind ful
ind1 ful
shp ful
ful
The fruitfull mutant phenotype is caused by
mis-expression of SHP and IND
Wild type
shp ind ful
ind ful
shp ful
ful
“Valve” is the “default” state
FUL is expressed in valve cells where it functions
to negatively regulate SHP and IND
SHP
IND
FUL
?
replum
valve
margin
valve
enb
replumless (rpl) mutant fails to form a replum
Wild type
replum
rpl
RPL encodes a homeobox protein and
is expressed in the replum
RPL
Are SHP and IND ectopically
expressed in the rpl mutant
replum?
IND is ectopically expressed
in the rpl mutant replum
VM
VM
R
wild type
rpl mutant
IND expression
Is the replumless mutant phenotype
caused by the ectopic expression
of the valve margin genes?
Mutations in SHP rescue rpl
Wild type
rpl
rpl shp
RPL is expressed in the replum and functions
to negatively regulated SHP and IND
SHP
IND
FUL
RPL
replum
valve
valve
margin
What happens in the ful rpl double mutant?
SHP
IND
FUL
RPL
replum
valve
valve
margin
All valve margin: rpl ful
valve replum
valve
SHP and IND are expressed
In the valve, valve margin
and replum regions in
rpl ful mutants
rpl ful
Genes controlling fruit development?
SHP
IND
FUL
RPL
replum
valve
valve
margin
The FUL gene is normally expressed in valves
replum
valve
What happens if the FUL gene is
mis-expressed in all cells of the fruit?
wild type
mis-expression of FRUITFULL converts
replum and valve margin cells into valve cells
replum
valve
wild type
35S::FUL
D/V Signaling Is Required for Wing Margin Formation and Wing Outgrowth
Ap -> Notch -> Wing Margin
= D/V Organizer
D
V
D/V Organizer -> Margin Formation
and Wing Growth
Activation of
Notch Along
ap Expressing Cells Future Margin
D ->V Signal
Loss of ap in Dorsal Cells
-> Margin Formation
ap - cells
V -> D Signal
ap Non-expressing
Cells
Wing imaginal disc in larva
Adult wing (viewed end on)
Adult wing withap- patch
Fig. 4.4
•Interactions between cells on the dorsal and ventral
surfaces of leaves result in the formation of a leaf margin,
which is required for leaf outgrowth.
Phantastica mutants, like apterous mutants in flies,
cannot form the dorsal surface of leaves.
•Loss of phantastica function leads to loss of leaf outgrowth.
•Partial loss of phantastica function leads to narrow leaves
that are cupped upwards due to fewer dorsal cells.
•Phantastica mutants illustrate that leaf outgrowth requires
interactions between dorsal and ventral cells.
•Weak phantastica mutants can have “islands”
of ventral cells on the dorsal surface.
•Marginal structures form at the border between
dorsal and ventral cells.
Conclusions
•In flies and plants, juxtaposition of dorsal and ventral surfaces
induces formation of an organizing margin.
•The organizing margin controls outgrowth of the appendage.