Is nitric oxide a critical key factor in ABA-induced stomatal closure?

U. van Meeteren*, M.E. Kaiser, P.R. Malcolm Matamoros, J.C. Verdonk, Sasan Aliniaeifard

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The role of nitric oxide (NO) in abscisic acid (ABA)-induced stomatal closure is a matter of debate. We conducted experiments in Vicia faba leaves using NO gas and sodium nitroprusside (SNP), a NO-donor compound, and compared their effects to those of ABA. In epidermal strips, stomatal closure was induced by ABA but not by NO, casting doubt on the role of NO in ABA-mediated stomatal closure. Leaf discs and intact leaves showed a dual dose response to NO: stomatal aperture widened at low dosage and narrowed at high dosage. Overcoming stomatal resistance by means of high CO2 concentration ([CO2]) restored photosynthesis in ABA-treated leaf discs but not in those exposed to NO. NO inhibited photosynthesis immediately, causing an instantaneous increase in intercellular [CO2] (Ci), followed by stomatal closure. However, lowering Ci by using low ambient [CO2] showed that it was not the main factor in NO-induced stomatal closure. In intact leaves, the rate of stomatal closure in response to NO was about one order of magnitude less than after ABA application. Because of the different kinetics of photosynthesis and stomatal closure that were observed, we conclude that NO is not likely to be the key factor in ABA-induced rapid stomatal closure, but that it fine-tunes stomatal aperture via different pathways.
Original languageEnglish
Pages (from-to)399-410
JournalJournal of Experimental Botany
Volume71
Issue number1
Early online date30 Sep 2019
DOIs
Publication statusPublished - Jan 2020

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