The rice MAPKK–MAPK interactome: the biological significance of MAPK components in hormone signal transduction

Abstract

Mitogen-activated protein kinase (MAPK) signaling cascades are evolutionarily conserved fundamental signal transduction pathways. A MAPK cascade consists of many distinct MAPKKK-MAPKK-MAPK modules linked to various upstream receptors and downstream targets through sequential phosphorylation and activation of the cascade components. These cascades collaborate in transmitting a variety of extracellular signals and in controlling cellular responses and processes such as growth, differentiation, cell death, hormonal signaling, and stress responses. Although MAPK proteins play central roles in signal transduction pathways, our knowledge of MAPK signaling in hormonal responses in rice has been limited to a small subset of specific upstream and downstream interacting targets. However, recent studies revealing direct MAPK and MAPKK interactions have provided the basis for elucidating interaction specificities, functional divergence, and functional modulation during hormonal responses. In this review, we highlight current insights into MAPKK-MAPK interaction patterns in rice, with emphasis on the biological significance of these interacting pairs in SA (salicylic acid), JA (jasmonic acid), ET (ethylene), and ABA (abscisic acid) responses, and discuss the challenges in understanding functional signal transduction networks mediated by these hormones.

Involvement of Potato (Solanum tuberosum L.) MKK6 in Response to Potato virus Y

“…All of these interactions had already been confirmed in A. thaliana [34], [69], [70]. In rice, OsMEK1 (or OsMKK6) interacts with OsMAPK1, -3, -5 and -6 (orthologues of AtMAPK6, -3 and -11/4, respectively [48], [63]). To date, only one MAPK interactor has been identified for the MKK6 orthologues in Solanaceae : in N. tabacum , NQK1/NtMEK1 was reported to interact with NTF6/NRK1 (orthologue of AtMAPK13 [64]).…”

“…To date, MKK genes have been analysed in several plants: in A. thaliana , 10 have been identified [4], in rice, 8 [48], in Brachypodium , 12 [49], in poplar, 10 [50], in apple, 9 [51] and in canola, 7 [52]. In the Solanaceae family, the MKK family is smaller than in other plant species.…”

Involvement of the OsMKK4-OsMPK1 Cascade and its Downstream Transcription Factor OsWRKY53 in the Wounding Response in Rice

“…Recently, a high-quality mapped MAPK interaction network in rice has been described using the yeast two-hybrid system and co-immunoprecipitation, pull-down, bimolecular fluorescence complementation, subcellular localization, and kinase assay experiments (Singh et al, 2012). However, only the two MAPKK-MAPK pairs, OsMKK4-OsMPK6 (OsMPK1) and OsMKK6-OsMPK3 (OsMPK5), have been functionally analyzed in rice so far (Singh and Jwa, 2013). In this study, we determined that OsMKK4 is the upstream kinase of OsMPK1 in wounding signaling pathway in rice.…”

Functional Involvement of a Mitogen Activated Protein Kinase Module, OsMKK3-OsMPK7-OsWRK30 in Mediating Resistance against Xanthomonas oryzae in Rice

“…A couple of studies performed to find interaction between rice MAPKs and MAPKKs have put forward some of the major MAPK modules of which only a few are functionally characterized820. A cascade consisting of OsMKK4-OsMPK3/6 has shown its negative role in MAMP-triggered immunity and positive regulator of drought, salt and cold stress20. OsMKK6 has been reported to be involved in regulating genes for biosynthesis of phytoalexin, a secondary metabolite known to get accumulated in Magnoporthe oryzae infected plants21.…”