repair and regeneration injury program includes: injury program new organ initiation primordium...
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Repair and regeneration
Injury program includes:
Injury program
New organ initiation
Primordium activation (dormant buds)
Vascular repair
Abscission
Damage control
Primary signalsO2
C2H4
Δ [IAA]
Δ [CK]
MeJ or SA
• Response to injury is local &/or systemic
Phenylalanine
Cinnamic acid
Cinnamyl CoA
Chalcone
Flavonoids
Phytoalexins
Ferulic acid
PAL
Chalcone synthase
aa+
+
Oligos
C2H4
MeJ
SA
Suberin
Lignin
IAA transport
Wall crosslinks
+
+
-
+
+
Proteinase inhibitors
Chitinase
Systemic = upregulation of PAL and chalcone synthase Damage control, ‘immune’ response in whole body
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 RAMStem
IAA apical dominance
CK made in rootsCK axillary/lateral bud growth
What happens if herbivore removes SAM?
RootCK Root Apical dominance
What happens if something chomps on root tip?
+ IAA
IAA-
CK
++
+
+
++
Applying what we knowCuttings 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 changeRelative [IAA] : [CK] important Higher [IAA] promotes root program Higher [CK] promotes stem program
Callus CK
Root program
Shoot program
IAA
+
+
-
-
How else do we apply what we know?Injury, moisture and darkness
– Layering– Grafting