SlMYC2 mediates stomatal movement in response to drought stress by repressing SlCHS1 expression

Abstract

Drought stress limits plant development and reproduction. Multiple mechanisms in plants are activated to respond to stress. The MYC2 transcription factor is a core regulator of the jasmonate (JA) pathway and plays a vital role in the crosstalk between abscisic acid (ABA) and JA. In this study, we found that SlMYC2 responded to drought stress and regulated stomatal aperture in tomato (Solanum lycopersicum). Overexpression of SlMYC2 repressed SlCHS1 expression and decreased the flavonol content, increased the reactive oxygen species (ROS) content in guard cells and promoted the accumulation of JA and ABA in leaves. Additionally, silencing the SlCHS1 gene produced a phenotype that was similar to that of the MYC2-overexpressing (MYC2-OE) strain, especially in terms of stomatal dynamics and ROS levels. Finally, we confirmed that SlMYC2 directly repressed the expression of SlCHS1. Our study revealed that SlMYC2 drove stomatal closure by modulating the accumulation of flavonol and the JA and ABA contents, helping us decipher the mechanism of stomatal movement under drought stress.

Jasmonic acid enhances osmotic stress responses by MYC2‐mediated inhibition of protein phosphatase 2C1 and response regulators 26 transcription factor in tomato

“…We identified 19 DEGs that increased and 17 DEGs that decreased under both control and stress conditions (Figure 2a; Table S6). Of these 36 DEGs, we found the negative regulator of ABA signaling, protein phosphatases type 2C ( SlPP2C1 , Solyc03g096670), and one chalcone synthase1 ( SlCHS1 , Solyc09g091510) that played a negative role in drought/ABA‐induced stomatal closure (Watkins et al., 2014; Xu et al., 2022). The stress‐induced elevated expression (FPKM Drought versus FPKM Control ) of these two negative regulators ( SlPP2C1 and SlCHS1 ) was inhibited by the elevation of endogenous JA levels (Figure 2b), suggesting that JA regulated stomatal movements by transcriptionally hindering the negative modulators related to the ABA signaling pathway.…”

“…MYC2 plays a crucial role in the dehydration stress memory response (Avramova, 2019). Xu et al (2022) recently reported that the MYC2 gene was induced by drought stress and played a positive role in regulating stomatal closure in tomato. The expression of MYC2 was also induced by MeJA treatment (Figure S5).…”

“…Several studies have demonstrated that Arabidopsis CHS1 scavenges ROS by synthesizing flavonols, thereby inhibiting stomatal closure (An et al, 2016;Watkins et al, 2014). Recently, Xu et al (2022) demonstrated that MYC2 directly binds to and negatively regulates the expression of SlCHS1 (Figure 6), which acts as an ROS scavenger in guard cells in tomato. Here, SlRR26 was shown to be a negative regulator of ROS production (Figures 4f-h and and 5f-h; Figure S11e,f), which was also regulated by MYC2 (Figures 2c,d and 6).…”

“…Images of stomata were obtained using a B302 Series Biological Microscope (Optec, Chongqing, China). The stomatal aperture of opened stomata was calculated by the width/length ratio according to Xu et al (2022).…”

AgMYB5, an MYB transcription factor from celery, enhanced β- carotene synthesis and promoted drought tolerance in transgenic Arabidopsis

“…In drought-stressed plants, ABA is a major phytohormone involved in regulating stomatal aperture [54]. According to the reports from Populus euphratica [55], Oryza sativa [56] and Solanum lycopersicum [57], plants increased drought tolerance by modulating stomatal closing. Our results showed that in comparison with WT, AgMYB5 transgenic lines inhibited water loss rate by reducing the degree of stomatal aperture, thereby enhanced drought tolerance.…”