Abstract
Micronutrient metals, such as Mn, Cu, Fe, and Zn, are essential heavy metals for plant growth and development, while Cd is a nonessential heavy metal that is highly toxic to both plants and humans. Our understanding of the molecular mechanisms underlying Cd and micronutrient metal accumulation in plants remains incomplete. Here, we show that OsFWL7, an FW2.2-like (FWL) family gene in Oryza sativa, is preferentially expressed in the root and encodes a protein localized to the cell membrane. The osfwl7 mutation reduces both the uptake and the root-to-shoot translocation of Cd in rice plants. Additionally, the accumulation of micronutrient metals, including Mn, Cu, and Fe, was lower in osfwl7 mutants than in the wildtype plants under normal growth conditions. Moreover, the osfwl7 mutation affects the expression of several heavy metal transporter genes. Protein interaction analyses reveal that rice FWL proteins interact with themselves and one another, and with several membrane microdomain marker proteins. Our results suggest that OsFWL7 is involved in Cd and micronutrient metal accumulation in rice. Additionally, rice FWL proteins may form oligomers and some of them may be located in membrane microdomains.
Highlights
Micronutrient metals, such as Mn, Cu, Fe, and Zn, are essential heavy metals for plant growth and development [1]
We found that the rice FWL proteins self-interact and interact with one another, and that some of them may be located in membrane microdomains
To test whether the FWL genes are involved in Cd response in rice, the expression patterns of six genes (OsFWL1–OsFWL4, OsFWL6, and OsFWL7) under Cd exposure at different concentrations were examined using reverse-transcription quantitative Plant Cadmium Resistance genes (PCRs) (RT-qPCR)
Summary
Micronutrient metals, such as Mn, Cu, Fe, and Zn, are essential heavy metals for plant growth and development [1]. Cd is a nonessential heavy metal that is highly toxic It disrupts plant growth and development, thereby substantially reducing crop yield. The loss-of-function mutation of this gene results in an extremely low Cd accumulation in roots, shoots, and grains, suggesting that OsNramp is a major transporter for Cd uptake in rice [4,6]. Cd taken up from soil is sequestered into the vacuoles of root cells, and OsHMA3—a P1B -type ATPase—plays an important role in this process [7,8]. This transporter is localized to the tonoplast of all root cells, and the expression of gene encoding OsHMA3 is unaffected by Cd treatment.
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