Open AccessABA ‐mediated regulation of stomatal density is OST 1‐independent
Author(s) -
Jalakas Pirko,
Merilo Ebe,
Kollist Hannes,
Brosché Mikael
Publication year - 2018
Publication title -
plant direct
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.211
H-Index - 11
ISSN - 2475-4455
DOI - 10.1002/pld3.82
Subject(s) - guard cell , abscisic acid , stomatal conductance , mutant , stomatal density , microbiology and biotechnology , chemistry , biology , botany , photosynthesis , biochemistry , gene
Stomata, small pores on the surfaces of leaves formed by a pair of guard cells, adapt rapidly to changes in the environment by adjusting the aperture width. As a long‐term response, the number of stomata is regulated during stomatal development. The hormone abscisic acid ( ABA ) regulates both processes. In ABA mediated guard cell signaling the protein kinase OPEN STOMATA 1 ( OST 1) has a central role, as stomatal closure in the ost1 mutant is impaired in response to ABA and to different environmental stimuli. We aimed to dissect the contribution of different ABA ‐related regulatory mechanisms in determining stomatal conductance, a combination of stomatal density and aperture width, and crossed the ost1 mutant with mutants that either decreased ( aba3 ) or increased ( cyp707a1/a3 ) the concentration of ABA in plants. The double mutant ost1 aba3 had higher stomatal conductance than either parent due to a combination of increased stomatal aperture width and higher stomatal density. In the triple mutant ost1 cyp707a1/a3 , stomatal conductance was significantly lower compared to ost1‐3 due to lower stomatal density. Further characterization of the single, double and triple mutants showed that responses to treatments that lead to stomatal closure were impaired in ost1 as well as ost1 aba3 and ost1 cyp707a1/a3 mutants, supporting a critical role for OST 1 in stomatal aperture regulation. On the basis of our results, we suggest that two signaling pathways regulate water flux from leaves, that is, stomatal conductance: an ABA ‐dependent pathway that determines stomatal density independent of OST 1; and an OST 1‐dependent pathway that regulates rapid changes in stomatal aperture.