Myrosinases, TGG1 and TGG2, Redundantly Function in ABA and MeJA Signaling in Arabidopsis Guard Cells

Abstract

Thioglucoside glucohydrolase (myrosinase), TGG1, is a strikingly abundant protein in Arabidopsis guard cells. We investigated responses of tgg1-3, tgg2-1 and tgg1-3 tgg2-1 mutants to abscisic acid (ABA) and methyl jasmonate (MeJA) to clarify whether two myrosinases, TGG1 and TGG2, function during stomatal closure. ABA, MeJA and H(2)O(2) induced stomatal closure in wild type, tgg1-3 and tgg2-1, but failed to induce stomatal closure in tgg1-3 tgg2-1. All mutants and wild type showed Ca(2+)-induced stomatal closure and ABA-induced reactive oxygen species (ROS)production. A model is discussed in which two myrosinases redundantly function downstream of ROS production and upstream of cytosolic Ca(2+) elevation in ABA and MeJA signaling in guard cells.

Elucidating the Role of Transport Processes in Leaf Glucosinolate Distribution

“…This suggests a specialized role for products of these enzymes in the epidermis, e.g. as part of leaf defense against microbial pathogens as suggested for 4-methoxy-indol-3-ylmethyl glucosinolate (Bednarek et al, 2009;Clay et al, 2009), or as compounds involved in stomatal closure after breakdown by myrosinases in guard cells (Zhao et al, 2008;Islam et al, 2009;Khokon et al, 2011). The strong allocation of 4-MTB toward the abaxial epidermis compared with remaining leaf sample (Supplemental Fig.…”

The Arabidopsis ETHYLENE RESPONSE FACTOR1 Regulates Abiotic Stress-Responsive Gene Expression by Binding to Different cis-Acting Elements in Response to Different Stress Signals

“…It is known that methyl jasmonate (MeJA) as well as ABA stimulates stomatal closure in many plant species (Gehring et al, 1997;Saito et al, 2008;Islam et al, 2009). MeJA recruits many ABA signaling components to induce stomatal closure, including the NAD(P)H oxidases AtrbohD and AtrbohF (Suhita et al, 2004), the Snf-related protein kinase OST1 (Suhita et al, 2004), the protein phosphatases 2C ABI1 and ABI2 (Munemasa et al, 2007), a regulatory subunit of protein phosphatase 2A, RCN1 (Saito et al, 2008), and the myrosinase TGG (Islam et al, 2009), suggesting that MeJA signaling is overlapped with ABA signaling in guard cells. As a downstream component of JA signaling, overexpression of ERF1 might enhance the signal of JA and indirectly affect stomatal aperture.…”

Plant Stress Surveillance Monitored by ABA and Disease Signaling Interactions

“…In regulation of merging signals for ABA-and JA-triggered stomatal closures, guard cell abundant myrosinase THIOGLUCOSIDE GLUCO-HYDROLASE1 (TGG1) may have a role. tgg1 showed defects in ABA-inhibition of inward K + -channel activity and stomatal opening (Zhao et al, 2008) and ttg1 ttg2 produced reduced responses in the ABA-and JA-induced stomatal closures (Islam et al, 2009) suggesting a role of glucosinolate metabolism in the guard cell ABA signaling.…”