Role of H₂O₂ dynamics in brassinosteroid‐induced stomatal closure and opening in Solanum lycopersicum

Abstract

Brassinosteroids (BRs) are essential for plant growth and development; however, their roles in the regulation of stomatal opening or closure remain obscure. Here, the mechanism underlying BR-induced stomatal movements is studied. The effects of 24-epibrassinolide (EBR) on the stomatal apertures of tomato (Solanum lycopersicum) were measured by light microscopy using epidermal strips of wild type (WT), the abscisic acid (ABA)-deficient notabilis (not) mutant, and plants silenced for SlBRI1, SlRBOH1 and SlGSH1. EBR induced stomatal opening within an appropriate range of concentrations, whereas high concentrations of EBR induced stomatal closure. EBR-induced stomatal movements were closely related to dynamic changes in H2O2 and redox status in guard cells. The stomata of SlRBOH1-silenced plants showed a significant loss of sensitivity to EBR. However, ABA deficiency abolished EBR-induced stomatal closure but did not affect EBR-induced stomatal opening. Silencing of SlGSH1, the critical gene involved in glutathione biosynthesis, disrupted glutathione redox homeostasis and abolished EBR-induced stomatal opening. The results suggest that transient H2O2 production is essential for poising the cellular redox status of glutathione, which plays an important role in BR-induced stomatal opening. However, a prolonged increase in H2O2 facilitated ABA signalling and stomatal closure.

Abscisic Acid-Induced Reactive Oxygen Species Are Modulated by Flavonols to Control Stomata Aperture

“…DCF and PO1 signals accumulate in the nucleus, as demonstrated by DCF colocalization with Hoechst stain, where ROS plays a role by changing the activity of redox-sensitive transcription factors (Willems et al, 2016). DCF signal has been observed previously in the guard cell cytoplasm (Lee et al, 1999;Kwak et al, 2003;Chen and Gallie, 2004;Watkins et al, 2014;Xia et al, 2014;, but the images within this data set use an Figure 7. Flavonoid mutants have altered stomatal opening in response to light.…”

“…Although tomato RBOH mutants are not available, SIRBOH1, a homolog of Arabidopsis RBOHF, has the target of virus-induced gene silencing to demonstrate that there is less CO 2 -and salt stress-induced stomatal closure and that the response to ABA is reduced Yi et al, 2015). Another study showed that brassinosteroid signaling functions through RBOH enzymes to induce stomatal closure (Xia et al, 2014). Together, these studies support the model that tomato guard cell closure requires an ABA-induced ROS burst, but what has not been examined in tomato is whether ROS homeostasis is regulated by antioxidants.…”

“…Given the essential function of guard cells in regulating gas exchange and water loss, a better understanding of how crop plants mediate ROS signaling is essential to improving crop health, productivity, and ability to deal with stressful growth environments. In tomato guard cells, increases in ROS accumulation in response to pathogen infections (Lee et al, 1999), hormone signaling (Xia et al, 2014;Farber et al, 2016), and CO 2 concentrations Yi et al, 2015) have been linked to stomatal closure; however, it is not clear that guard cell closure in this species works through an ABA-induced ROS burst, as observed in Arabidopsis. Additionally, the antioxidant networks in tomato guard cells that regulate ROS signaling remain uncharacterized.…”

Brassinosteroids improve photosystem II efficiency, gas exchange, antioxidant enzymes and growth of cowpea plants exposed to water deficit

“…EBR also caused an increase in E and g s , which was induced by the increase in the W w previously described. The stomatal mechanism is dependent on the water status of the tissue and has a strong influence on gas exchange (Dias and Brüggemann 2010;Xia et al 2014). Afzal et al (2014) evaluated the gas exchange of Vigna radiata plants under a water deficit and also found reductions in P N and g s .…”

Reactive Oxygen Species Function to Mediate the Fe Deficiency Response in an Fe-Efficient Apple Genotype: An Early Response Mechanism for Enhancing Reactive Oxygen Production

“…Some species, such as tomato ( Solanum lycopersicum ), lettuce ( Lactuca sativa ), peanut ( Arachis hypogaea ), and apple rootstock ( Malus xiaojinensis and Malus baccata ), show different levels of resistance to Fe deficiency among genotypes (Han et al, 1994, 1998; Wang and Li, 1995; Xu et al, 2009; Sun et al, 2013; Xia et al, 2014). Self-incompatible species, such as apple, have higher levels of genetic variation, and the use of highly heterozygous Malus genotypes allowed us to identify an Fe-efficient woody plant in which to study the role of ROS in the response to Fe deficiency.…”