Strigolactone‐triggered stomatal closure requires hydrogen peroxide synthesis and nitric oxide production in an abscisic acid‐independent manner

Abstract

SummaryAccumulating data indicate that strigolactones (SLs) are implicated in the response to environmental stress, implying a potential effect of SLs on stomatal response and thus stress acclimatization. In this study, we investigated the molecular mechanism underlying the effect of SLs on stomatal response and their interrelation with abscisic acid (ABA) signaling.The impact of SLs on the stomatal response was investigated by conducting SL-feeding experiments and by analyzing SL-related mutants. The involvement of endogenous ABA and ABA-signaling components in SL-mediated stomatal closure was physiologically evaluated using genetic mutants. Pharmacological and genetic approaches were employed to examine hydrogen peroxide (H 2 O 2 ) and nitric oxide (NO) production.SL-related mutants exhibited larger stomatal apertures, while exogenous SLs were able to induce stomatal closure and rescue the more widely opening stomata of SL-deficient mutants. The SL-biosynthetic genes were induced by abiotic stress in shoot tissues. Disruption of ABA-biosynthetic genes, as well as genes that function in guard cell ABA signaling, resulted in no impairment in SL-mediated stomatal response. However, disruption of MORE AXILLARY GROWTH2 (MAX2), DWARF14 (D14), and the anion channel gene SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) impaired SL-triggered stomatal closure. SLs stimulated a marked increase in H 2 O 2 and NO contents, which is required for stomatal closure.Our results suggest that SLs play a prominent role, together with H 2 O 2 /NO production and SLAC1 activation, in inducing stomatal closure in an ABA-independent mechanism.

Strigolactones in plant adaptation to abiotic stresses: An emerging avenue of plant research

“…On the other hand, the transcript levels of the SL‐biosynthetic genes D27 and MAX1 ‐homologues Os01g0701400 , Os01g0700900 , Os02g0221900 , and Os06g0565100 were upregulated in rice shoots, as was observed for SlCCD7 and SlCCD8 in the case of tomato (Haider et al, ; Visentin et al, ). These data were in agreement with the detection of increased transcript levels of SL‐biosynthetic genes MAX3 and MAX4 in the leaves of Arabidopsis upon dehydration (C. V. Ha et al, ) and NaCl and mannitol treatments (Lv et al, ), as well as with the upregulation of the SL‐biosynthetic FaD17 gene in the crowns of tall fescue ( Festuca arundinacea ) and the D10 , D17 , and D27 genes in the base of rice stems under drought stress (Table ; Du et al, ; Zhuang et al, ). Collectively, these findings suggest that the induction of SL synthesis in the aboveground organs of plants is triggered in response to osmotic stress.…”

“…It is worth mentioning that treatment of broad bean ( Vicia faba ) with GR24 enhanced stomatal closure in a concentration‐dependent manner (Y. Zhang et al, ). Very recently, Lv et al () reported that rac ‐GR24 induced the production of H 2 O 2 and NO that were required for promoting SL‐mediated stomatal closure in Arabidopsis . These results may imply a potential crosstalk between SL or SL‐like compounds with H 2 O 2 /NO signalling pathways in regulating plant acclimatization to external stresses (Figure ).…”

“…As mutants of SL biosynthesis and signalling became available over the last decade (e.g., mutants with mutation in MORE AXILLARY GROWTH [ MAX ] genes in Arabidopsis thaliana , DWARF [ D ] genes in rice [ Oryza sativa ], RAMOSUS [ RMS ] genes in pea [ Pisum sativum ], and DECREASED APICAL DOMINANCE [ DAD ] genes in Petunia hybrida ), various loss‐of‐function studies have reported the involvement of SLs in many aspects of plant development, particularly in the regulation of root system architecture, branching, photo‐morphogenesis, early seedling development, secondary growth, and leaf senescence (Brewer, Koltai, & Beveridge, ; Kapulnik, Delaux, et al, ; Toh et al, ; Ueda & Kusaba, ; Umehara et al, ; Urquhart, Foo, & Reid, ). Genetic studies also provided evidence that the biosynthesis of SLs is regulated by various abiotic stresses, including nutrient deprivation, drought, and salinity (Du et al, ; C. V. Ha et al, ; Lv et al, ; H. Sun et al, ; Umehara, Hanada, Magome, Takeda‐Kamiya, & Yamaguchi, ; Visentin et al, ; Zhuang, Wang, & Huang, ). These findings collectively provided important clues regarding the potential of SLs in regulating plant responses and adaptation to environmental stresses.…”

“…These findings collectively provided important clues regarding the potential of SLs in regulating plant responses and adaptation to environmental stresses. Thus, an increasing number of studies have recently focused on the implications of SLs in the adaptation of plants to environmental constraints and have reported many novel findings (Bu et al, ; Cooper et al, ; C. V. Ha et al, ; Liu et al, ; Lv et al, ; Ma et al, ; Ruiz‐Lozano et al, ; Umehara et al, ; Visentin et al, ; Y. Zhang, Lv, & Wang, ). Moreover, the connection of SLs in AM symbiosis‐mediated improvement of physiological responses has also been reported in plants under abiotic stresses, such as high salinity and drought (Aroca et al, ; Ruiz‐Lozano et al, ).…”

Interactive effects of abscisic acid and nitric oxide on chilling resistance and active oxygen metabolism in peach fruit during cold storage

“…In recent years, the interactions between NO and ABA have been studied, and NO is now considered as an important participant in ABA‐mediated signaling pathways. NO participates downstream in the effects of ABA on processes such as stomata movement and oxidative tolerance . However, there have been few studies of the roles of NO–ABA interactions in chilling stress and antioxidant defense in horticultural plants.…”