Plant neighbor detection through touching leaf tips precedes phytochrome signals.
Plants in dense vegetation compete for resources, including light, and optimize their growth based on neighbor detection cues. The best studied of such behaviors is the shade-avoidance syndrome that positions leaves in optimally lit zones of a vegetation. Although proximate vegetation is known to be sensed through a reduced ratio between red and far-red light, we show here through computational modeling and manipulative experiments that leaves of the rosette species Arabidopsis thaliana first need to move upward to generate sufficient light reflection potential for subsequent occurrence and perception of a reduced red to far-red ratio. This early hyponastic leaf growth response is not induced by known neighbor detection cues under both climate chamber and natural sunlight conditions, and we identify a unique way for plants to detect future competitors through touching of leaf tips. This signal occurs before light signals and appears to be the earliest means of above-ground plant-plant signaling in horizontally growing rosette plants.
Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, 3584 CH Utrecht, The Netherlands.
Mieke
M
de Wit
Wouter
W
Kegge
Jochem B
JB
Evers
Marleen H
MH
Vergeer-van Eijk
Paulien
P
Gankema
Laurentius A C J
LA
Voesenek
Ronald
R
Pierik
D000704:Analysis of Variance; D017360:Arabidopsis / Q000502:physiology* / Q000528:radiation effects; D002849:Chromatography, Gas; D003198:Computer Simulation; D005030:Ethylenes / Q000378:metabolism; D008027:Light; D055537:Light Signal Transduction / Q000502:physiology; D046228:Microarray Analysis; D008954:Models, Biological; D010812:Physical Stimulation; D063245:Plant Development / Q000502:physiology* / Q000528:radiation effects; D018515:Plant Leaves / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D005030:Ethylenes; C036216:ethylene