Transcript Repair and regeneration

Repair and regeneration
Injury program includes:
Damage control
Abscission
Injury program
Vascular repair
Primordium activation (dormant buds)
New organ initiation
Primary signals
O2
C2H4
Δ [IAA]
Δ [CK]
MeJ or SA
• Response to injury is local &/or systemic
Systemic = upregulation of PAL and chalcone synthase
Damage control, ‘immune’ response in whole body
Phenylalanine
Wall crosslinks
PAL
+
Oligos
C2H4
MeJ
SA
+
aa
+
Cinnamic acid
+
Lignin
+
Chalcone
Proteinase inhibitors
Chitinase
Ferulic acid
Cinnamyl CoA
Chalcone synthase
+
IAA transport
Flavonoids
Phytoalexins
Suberin
Local response might involve vascular repair
Cork forms over injury
Parenchyma cells de-differentiate  procambium  vascular
tissue
– Dedifferentiation doesn’t occur until vasculature is broken
– IAA and CK activate dedifferentiation
Local response may include organ replacement
Dormant primordia released
– Leaf
– Axillary/lateral buds
• Stem primordia
– Root
Root external view of
primordia
Hormones affect apical dominance;
injury
to
SAM
or
RAM
Stem
IAA  apical dominance
+
+
CK made in roots
CK  axillary/lateral bud growth
+
IAA
IAA
+
+
CK
What happens if herbivore removes SAM?
Root
+ +
CK  Root Apical dominance
What happens if something chomps on root tip?
Applying what we know
Cuttings of stems, tubers, corms
– Hybrids
– Seedless plants
Tissue culture
– Orchids; transgenic species;
nursery species
How do we regenerate organs?
Injury causes:
Parenchyma cells to dedifferentiate  callus
Hormone concentrations to change
Relative [IAA] : [CK] important
Shoot program
Higher [IAA] promotes root program
Higher [CK] promotes stem program
-
+
Callus
IAA
CK
-
+
Root program
How else do we apply what we know?
Injury, moisture and darkness
– Layering
– Grafting