Arabidopsis MAP3K16 and Other Salt-Inducible MAP3Ks Regulate ABA Response Redundantly

Abstract

In the Arabidopsis genome, approximately 80 MAP3Ks (mitogen-activated protein kinase kinase kinases) have been identified. However, only a few of them have been characterized, and the functions of most MAP3Ks are largely unknown. In this paper, we report the function of MAP3K16 and several other MAP3Ks, MAP3K14/15/17/18, whose expression is salt-inducible. We prepared MAP3K16 overexpression (OX) lines and analyzed their phenotypes. The result showed that the transgenic plants were ABA-insensitive during seed germination and cotyledon greening stage but their root growth was ABA-hypersensitive. The OX lines were more susceptible to water-deficit condition at later growth stage in soil. A MAP3K16 knockout (KO) line, on the other hand, exhibited opposite phenotypes. In similar transgenic analyses, we found that MAP3K14/15/17/18 OX and KO lines displayed similar phenotypes to those of MA3K16, suggesting the functional redundancy among them. MAP3K16 possesses in vitro kinase activity, and we carried out two-hybrid analyses to identify MAP3K16 substrates. Our results indicate that MAP3K16 interacts with MKK3 and the negative regulator of ABA response, ABR1, in yeast. Furthermore, MAP3K16 recombinant protein could phosphorylate MKK3 and ABR1, suggesting that they might be MAP3K16 substrates. Collectively, our results demonstrate that MAP3K16 and MAP3K14/15/17/18 are involved in ABA response, playing negative or positive roles depending on developmental stage and that MAP3K16 may function via MKK3 and ABR1.

Nuclear Signaling of Plant MAPKs

“…The authors also reported the in vitro phosphorylation of WRKY53 by MEKK1, but no in planta evidence has supported this result yet. Likewise, Arabidopsis MAP3K16 interacts with and phosphorylates in vitro the negative regulator of ABA response ABR1, but here as well in planta evidence is lacking (Choi et al, 2017 ). Arabidopsis MAP3K20 directly interacts with MPK18 and phosphorylates MPK18 in vitro on the TDY motif of its activation loop (Benhamman et al, 2017 ).…”

Mitogen-Activated Protein Kinase CaDIMK1 Functions as a Positive Regulator of Drought Stress Response and Abscisic Acid Signaling in Capsicum annuum

“…Both drought stress and high salinity decrease the water availability to plant cells and also cause the accumulation of ROS such as hydrogen peroxide ( Hasegawa et al, 2000 ). As homologs of CaDIMK1, AtMAPKKK15/16/17/18 are salt-inducible MEKK genes ( Choi et al, 2017 ). In rice, OsMAPKKK63 is also induced by salt and its loss-of-function mutant shows decreased tolerance to salt stress ( Na et al, 2019 ).…”

Transcriptomic profiling of wheat near-isogenic lines reveals candidate genes on chromosome 3A for pre-harvest sprouting resistance

“…KEGG enrichment assigned the gene to plant MAPK signaling pathway. The MAPK module directly responds to ABA, or interacts with MKK3; for example, MAP3K16 is the negative regulator of ABA response (ABR1), and MAP3K17/18-MKK3-MPK1/2/7/14 responds to ABA, senescence and dormancy in Arabidopsis [ 57 , 58 ]. MKK3 contains an NTF2 domain and its primary gene structure is highly conserved during evolution [ 59 ].…”