Changes in endogenous abscisic acid and stomata of the resurrection fern, Pleopeltis polypodioides, in response to de‐ and rehydration

Abstract

Premise While angiosperms respond uniformly to abscisic acid (ABA) by stomatal closure, the response of ferns to ABA is ambiguous. We evaluated the effect of endogenous ABA, hydrogen peroxide (H2O2), nitric oxide (NO), and Ca2+, low and high light intensities, and blue light (BL) on stomatal opening of Pleopeltis polypodioides. Methods Endogenous ABA was quantified using gas chromatography‐mass spectrometry; microscopy results and stomatal responses to light and chemical treatments were analyzed with Image J. Results The ABA content increases during initial dehydration, peaks at 15 h and then decreases to one fourth of the ABA content of hydrated fronds. Following rehydration, ABA content increases within 24 h to the level of hydrated tissue. The stomatal aperture opens under BL and remains open even in the presence of ABA. Closure was strongly affected by BL, NO, and Ca2+, regardless of ABA, H2O2 effect was weak. Conclusions The decrease in the ABA content during extended dehydration and insensitivity of the stomata to ABA suggests that the drought tolerance mechanism of Pleopeltis polypodioides is independent of ABA.

Abscisic acid induces stomatal closure in horsetails

“…As an exception, in 2019 E. pratense showed no stomatal closure when CO 2 concentration increased, but upon returning to initial CO 2 , the stomatal conductance reached higher values than the previous steady-state conductance. CO 2 -induced stomatal closure of ferns and allies was also detected in other experiments (Ruszala et al, 2011;Franks & Britton-Harper, 2016;Hõrak et al, 2017;K€ ubarsepp et al, 2020). Stomatal responses of ferns and horsetails to changes in CO 2 concentration seem to be less dependent on growth conditions.…”

“…In accordance, the values of steady-state pretreatment transpiration of horsetails remained well below 1 mmol m À2 s À1 , whereas Arabidopsis transpiration in the respective conditions was c. 2 mmol m À2 s À1 (Tulva et al, 2023). Relatively low values of transpiration and stomatal conductance of horsetails and ferns have been associated with their lower stomatal density (Franks & Beerling, 2009;K€ ubarsepp et al, 2020;Wuyun et al, 2023), reduced hydraulic conductance (Brodribb et al, 2005) and relatively large investment into secondary metabolites (Cândido-Sobrinho et al, 2022). Lower transpiration of ferns may be a factor explaining why ABA-induced stomatal closure is not detected when ABA is applied via petiole feeding (Brodribb & McAdam, 2011 (g) E. pratense in the gas exchange measurement cuvette.…”

“…However, their ABA responses were conditional and depended on species and growing season, whereas CO 2 responsiveness was more common, being present also when ABA sensitivity was absent. Recently, data by John et al (2023) added another angle to the fern ABA sensitivity debate: they found that even though the stomata of Pleopeltis polypodioides responded directly to ABA only under very low light, application of ABA together with different other signalling molecules (NO, Ca 2+ ) was able to modulate the subsequent stomatal response. Thus, in addition to a direct effect on stomatal aperture width, ABA may indirectly affect stomatal regulation of ferns and horsetails via changes in signalling molecules involved in stomatal regulation.…”

“…Thus, in addition to a direct effect on stomatal aperture width, ABA may indirectly affect stomatal regulation of ferns and horsetails via changes in signalling molecules involved in stomatal regulation. However, whether the stomata of all ferns and lycophytes respond to these messengers, for example Ca 2+ , is not unequivocally clear either Gong et al, 2021;John et al, 2023).…”

Desiccation tolerance in the resurrection plant Barbacenia graminifolia involves changes in redox metabolism and carotenoid oxidation

“…(2021) , violaxanthin and neoxanthin can be converted into 9-cis-violaxanthin and 9’-cis-neoxanthin by 9-cis-epoxycarotenoid dioxygenases (NCEDs) producing xanthoxin, which is then converted into ABA. The signaling-protection role of the ABA apocarotenoid has been well demonstrated in several resurrection plants ( Rodriguez et al., 2010 ; Djilianov et al., 2013 ; Vieira et al., 2017a ; Gu et al., 2019 ; John et al., 2023 ).…”