Mild osmotic stress promotes 4-methoxy indolyl-3-methyl glucosinolate biosynthesis mediated by the MKK9-MPK3/MPK6 cascade in Arabidopsis

Plant Cell Rep (2017) 36:543555 DOI 10.1007/s00299-017-2101-8

ORIGINAL ARTICLE

http://orcid.org/0000-0003-2979-0803

Web End = Received: 31 August 2016 / Accepted: 3 January 2017 / Published online: 2 February 2017 Springer-Verlag Berlin Heidelberg 2017

MKK9. Gene expression analyses indicated that the activated MKK9MPK3/MPK6 cascade upregulates the IGS biosynthetic genes. Moreover, the lack of MYB51, the transcription factor controlling biosynthetic genes responsible for synthesizing the IGS core structure, or CYP81F2, the enzyme catalyzing core structure modication to 4MI3G, signicantly reduced mild osmotic stress- and MKK9DD-

induced 4MI3G. Thus, our study demonstrates that mild osmotic stress promotes 4MI3G biosynthesis and the accumulation in Arabidopsis through activation of the MKK9 MPK3/MPK6 cascade and provides an MAPK-mediated signaling pathway for the IGS response to abiotic stress in plants.

Keywords Arabidopsis Mild osmotic stress MKK9

MPK3/MPK6 cascade IGS 4MI3G

Introduction

Osmotic stress is a result of plant cell dehydration and is usually caused by drought, salinity or low temperature, which all lead to reduced water availability (Boudsocq and Lauriere 2005; Zhu 2002). Under osmotic stress conditions, a plethora of changes, such as biosynthesis of abscisic acid (ABA), activation of specic signaling pathways, and alterations in gene expression patterns, occur at the cellular level to actively respond and adapt to the stress. Osmotic adjustment by solute accumulation is the most important physiological mechanism, which functions to reduce cellular water potential, decrease water loss, and increase water uptake. Osmolytes, including proline, glycine, betaine, sugar alcohols, and polyamines, are synthesized and accumulate in the cytoplasm under osmotic conditions to increase stress tolerance (Arbona etal. 2013; Golldack

Vol.:(0123456789)

http://crossmark.crossref.org/dialog/?doi=10.1007/s00299-017-2101-8&domain=pdf

Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s00299-017-2101-8&domain=pdf

Web End = Mild osmotic stress promotes 4-methoxy indolyl-3-methyl glucosinolate biosynthesis mediated bytheMKK9MPK3/MPK6 cascade inArabidopsis

LuoZhao1 ChuchuWang2 FanZhu1 YuanLi1http://orcid.org/0000-0003-2979-0803

Web End =

Abstract

Key message MKK9MPK3/MPK6 cascade positively regulates IGSs biosynthetic genes.

Abstract Glucosinolates (GSs), secondary metabolites well known for their roles in plant defense, have been implicated to play an important role in plant abiotic stress response; however, the exact role in these processes and the underlying regulatory mechanisms remain elusive. Mitogen-activated protein kinase (MAPK) cascades are extensively involved in plant abiotic stress response. In this study, we examined the levels of four indolic glucosinolates (IGSs) in the shoots of Arabidopsis seedlings under mild osmotic stress conditions and found that 4-methoxy indolyl-3-methyl...