A novel WD40-repeat protein involved in formation of epidermal bladder cells in the halophyte quinoa

Tomohiro Imamura,Kanako Nishizawa,Hiroharu Mizukoshi,Hiroki Takagi,Nobuyuki Mizuno,Yasuo Yasui,Shinya Ohki,Hironori Koga,Akira Abe,Masashi Mori

doi:10.1038/s42003-020-01249-w

Abstract

Halophytes are plants that grow in high-salt environments and form characteristic epidermal bladder cells (EBCs) that are important for saline tolerance. To date, however, little has been revealed about the formation of these structures. To determine the genetic basis for their formation, we applied ethylmethanesulfonate mutagenesis and obtained two mutants with reduced levels of EBCs (rebc) and abnormal chloroplasts. In silico subtraction experiments revealed that the rebc phenotype was caused by mutation of REBC, which encodes a WD40 protein that localizes to the nucleus and chloroplasts. Phylogenetic and transformant analyses revealed that the REBC protein differs from TTG1, a WD40 protein involved in trichome formation. Furthermore, rebc mutants displayed damage to their shoot apices under abiotic stress, suggesting that EBCs may protect the shoot apex from such stress. These findings will help clarify the mechanisms underlying EBC formation and function.

Highlights

Halophytes are plants that grow in high-salt environments and form characteristic epidermal bladder cells (EBCs) that are important for saline tolerance
In this study, we identified the gene involved in EBC formation and a novel EBC function in the halophyte quinoa
In silico subtraction experiments revealed that mutation of the REDUCED EPIDERMAL BLADDER CELLS” (REBC) gene was responsible for the rebc phenotype

Summary

Introduction

Halophytes are plants that grow in high-salt environments and form characteristic epidermal bladder cells (EBCs) that are important for saline tolerance. Rebc mutants displayed damage to their shoot apices under abiotic stress, suggesting that EBCs may protect the shoot apex from such stress. These findings will help clarify the mechanisms underlying EBC formation and function. A positive correlation between the amount of EBCs and salt stress tolerance was reported in quinoa[11]; quinoa plants in which EBCs have been artificially removed are less tolerant to salt[12] These findings indicate EBCs are involved in relieving high salt stress in plants by accumulating high salt concentrations.

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Conclusion