Mitogen activated protein kinase 6 and MAP kinase phosphatase 1 are involved in the response of Arabidopsis roots to l-glutamate

Abstract

The function and components of L-glutamate signaling pathways in plants have just begun to be elucidated. Here, using a combination of genetic and biochemical strategies, we demonstrated that a MAPK module is involved in the control of root developmental responses to this amino acid. Root system architecture plays an essential role in plant adaptation to biotic and abiotic factors via adjusting signal transduction and gene expression. L-Glutamate (L-Glu), an amino acid with neurotransmitter functions in animals, inhibits root growth, but the underlying genetic mechanisms are poorly understood. Through a combination of genetic analysis, in-gel kinase assays, detailed cell elongation and division measurements and confocal analysis of expression of auxin, quiescent center and stem cell niche related genes, the critical roles of L-Glu in primary root growth acting through the mitogen-activated protein kinase 6 (MPK6) and the dual specificity serine-threonine-tyrosine phosphatase MKP1 could be revealed. In-gel phosphorylation assays revealed a rapid and dose-dependent induction of MPK6 and MPK3 activities in wild-type Arabidopsis seedlings in response to L-Glu. Mutations in MPK6 or MKP1 reduced or increased root cell division and elongation in response to L-Glu, possibly modulating auxin transport and/or response, but in a PLETHORA1 and 2 independent manner. Our data highlight MPK6 and MKP1 as components of an L-Glu pathway linking the auxin response, and cell division for primary root growth.

Biostimulant Properties of Protein Hydrolysates: Recent Advances and Future Challenges

“…Chinensis L.) [75]. Isolated AAs, including leucine (L-Leu), lysine (L-Lys), tryptophan (L-Trp), and glutamate (L-Glu), repress cell division and elongation in Arabidopsis primary roots [76], and its effect could be associated with auxin-and mitogen-activated protein kinase (MAPK) signaling [76,77]. All these findings indicate that PHs can improve the root system architecture, and future investigations will be performed to decipher regulatory molecular networks and understand cross-talks between hormones and peptides in PH-controlled root physiology.…”

Why did glutamate, GABA, and melatonin become intercellular signalling molecules in plants?

“…Nitrate, acting as a signal at the root tip, abolishes the glutamate primary root inhibition effect ( Walch-Liu and Forde, 2008 ). At least two mitogen-activated protein kinase (MAPK) pathways were implicated in this process ( Forde et al, 2013 ; López-Bucio et al, 2018 ). It was also suggested that auxin is acting downstream of glutamate ( Walch-Liu et al, 2006 ), and it might be the case that auxin acts downstream from one of these MAPK pathways.…”

Importance of Tyrosine Phosphorylation in Hormone-Regulated Plant Growth and Development

“…Given the fact that Tyr phosphorylation of MPKs is required for their activation [ 89 , 90 ], these studies support a potential role of Tyr phosphorylation in modulating the auxin signaling. A recent study also implicated MPK6 and MAP Kinase Phosphatase 1 (MKP1), a known DUSP that could dephosphorylate pSer/pThr/pTyr residues [ 91 ], in a growth response of Arabidopsis roots to L-Glutamate by regulating auxin distribution and response [ 92 ]. A recent chemical biology study has demonstrated a role of the auxin-induced phosphorylation at Tyr248 residue ( Figure 2 and Table 1 ) of an Arabidopsis Receptor for Activated C Kinase 1 (RACK1, a WD-40 type scaffold protein) in the auxin-mediated lateral root development [ 65 ].…”