MxMPK6-2-bHLH104 interaction is involved in reactive oxygen species signaling in response to iron deficiency in apple rootstock

Duyue Li; Qiran Sun; Guifen Zhang; Longmei Zhai; Keting Li; Yi Feng; Ting Wu; Xinzhong Zhang; Xuefeng Xu; Yi Wang; Zhenhai Han

doi:10.1093/jxb/eraa547

MxMPK6-2-bHLH104 interaction is involved in reactive oxygen species signaling in response to iron deficiency in apple rootstock

J Exp Bot. 2021 Feb 27;72(5):1919-1932. doi: 10.1093/jxb/eraa547.

Authors

Duyue Li^{1

2}, Qiran Sun^{1

2}, Guifen Zhang^{1

2}, Longmei Zhai^{1

2}, Keting Li^{1

2}, Yi Feng^{1

2}, Ting Wu^{1

2}, Xinzhong Zhang^{1

2}, Xuefeng Xu^{1

2}, Yi Wang^{1

2}, Zhenhai Han^{1

2}

Affiliations

¹ College of Horticulture, China Agricultural University, Beijing, P. R. China.
² Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology), Ministry of Agriculture, Beijing, P. R. China.

PMID: 33216933
DOI: 10.1093/jxb/eraa547

Abstract

Iron (Fe) is a trace element necessary for plant growth. Many land plants have evolved a set of mechanisms associated with the Fe absorption process to deal with the problem of insufficient Fe supply in the soil. During Fe absorption, reactive oxygen species (ROS) can be used as a signal to initiate a response to stress caused by Fe deficiency. However, the molecular mechanisms underlying the involvement of ROS in the Fe deficiency stress response remains unclear. In this study, we have identified a kinase, MxMPK6-2, from Malus xiaojinensis, an apple rootstock that is highly efficient at Fe absorption. MxMPK6-2 has been shown to be responsive to ROS signals during Fe deficiency, and MxMPK6-2 overexpression in apple calli enhanced its tolerance to Fe deficiency. We further screened for proteins in the Fe absorption pathway and identified MxbHLH104, a transcription factor which interacts with MxMPK6-2. MxbHLH104 can be phosphorylated by MxMPK6-2 in vivo, and we confirmed that its phosphorylation increased Fe absorption in apple calli under Fe deficiency, with the presence of ROS promoting this process. Overall, we have demonstrated that MxMPK6-2 is responsive to ROS signaling during Fe deficiency, and is able to control its response by regulating MxbHLH104.

Keywords: Malus xiaojinensis; Fe deficiency; MAPK; ROS; bHLH104; phosphorylation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anemia, Iron-Deficiency*
Basic Helix-Loop-Helix Transcription Factors* / genetics
Basic Helix-Loop-Helix Transcription Factors* / metabolism
Gene Expression Regulation, Plant
Iron / metabolism
Malus* / genetics
Malus* / metabolism
Mitogen-Activated Protein Kinases* / genetics
Mitogen-Activated Protein Kinases* / metabolism
Plant Proteins* / genetics
Plant Proteins* / metabolism
Reactive Oxygen Species / metabolism*

Substances

Basic Helix-Loop-Helix Transcription Factors
Plant Proteins
Reactive Oxygen Species
Iron
Mitogen-Activated Protein Kinases