Actin filament reorganisation controlled by the SCAR/WAVE complex mediates stomatal response to darkness
Résumé
Stomata respond to darkness by closing to prevent excessive water loss during the night.
Although the reorganisation of actin filaments during stomatal closure is documented, the
underlying mechanisms responsible for dark-induced cytoskeletal arrangement remain largely
unknown.
We used genetic, physiological and cell biological approaches to show that reorganisation
of the actin cytoskeleton is required for dark-induced stomatal closure.
The opal5 mutant does not close in response to darkness but exhibits wild-type (WT)
behaviour when exposed to abscisic acid (ABA) or CaCl2. The mutation was mapped to
At5g18410, encoding the PIR/SRA1/KLK subunit of the Arabidopsis SCAR/WAVE complex.
Stomata of an independent allele of the PIR gene (Atpir-1) showed reduced sensitivity to
darkness and F1 progenies of the cross between opal5 and Atpir-1 displayed distorted leaf trichomes, suggesting that the two mutants are allelic. Darkness induced changes in the extent
of actin filament bundling in WT. These were abolished in opal5. Disruption of filamentous
actin using latrunculin B or cytochalasin D restored wild-type stomatal sensitivity to darkness
in opal5.
Our findings suggest that the stomatal response to darkness is mediated by reorganisation
of guard cell actin filaments, a process that is finely tuned by the conserved SCAR/WAVE–
Arp2/3 actin regulatory module.
Domaines
Sciences du Vivant [q-bio]
Origine : Publication financée par une institution
Licence : CC BY - Paternité
Licence : CC BY - Paternité