4-2-10
Plant Signaling
Many cascade pathways in plants are similar to those in animals, but studies of them are not as clear as
in animals.
Cross Talking Molecules (Present in both animals and plants)
Norepinephrin
Serotonin, dopamine, acetylcholine (all neurotransmitters)
Glutamine
Polyamines
GABA
Because plants and animals contain many of the same signaling molecules, it is probable that
they are able to communicate at the cellular level
Similarities
Plants and animals evolved from a common ancestor around 2 billion years ago
As the organisms evolved in complexity, their signal pathways remained relatively unchanged
structurally, but the way they were used within cells changed over time
Both plants and animals evolved (separately) into multicellular organisms
Plants acquired chloroplasts, which provided them with an abundance of carbohydrates that
allowed them to change the nature of the ECM and form cell walls
Animal cells retained their flexibility and did not develop cell walls
Differences in cell signaling pathways are many times due to differences in the ECM
Plants have Many Receptors Animals Don’t
Light ligands
oMeasure quality (color)
oAmount
oDuration
oDirection
Mechanical pressure ligands (plants are more sensitive to touch than animals)
oWind
oHerbivores
Environmental sensing ligands
oHumidity
oTemperature
Each of these ligands must have a receptor system that affects growth changes within the cell.
Plants can be Immortal
Plants restrict their cells’ mitosis to the apical meristem (95% is localized here)
Plant cells don’t grow by mitosis, but by cell elongation in the zone of elongation
Long cells are pushed further away from the apical meristem and grow into functioning, mature
cells in the zone of maturation
Receptors are different in the three zones of the meristem
Response pathways in the three zones are the same, but the outcomes of them are different
There is no evidence of RTKs in plants
