SWO1 modulates cell wall integrity under salt stress by interacting with importin \u0251 in Arabidopsis

Zhidan Wang,Chunzhao Zhao,Guochen Qin,Li Peng,Wenfeng Nie,Huazhong Shi,Chun-Peng Song,Lun Zhao,Jian-Kang Zhu,Changhong Yang,Mugui Wang,Qijie Zheng

doi:10.1007/s44154-021-00010-5

Abstract

Maintenance of cell wall integrity is of great importance not only for plant growth and development, but also for the adaptation of plants to adverse environments. However, how the cell wall integrity is modulated under salt stress is still poorly understood. Here, we report that a nuclear-localized Agenet domain-containing protein SWO1 (SWOLLEN 1) is required for the maintenance of cell wall integrity in Arabidopsis under salt stress. Mutation in SWO1 gene results in swollen root tips, disordered root cell morphology, and root elongation inhibition under salt stress. The swo1 mutant accumulates less cellulose and pectin but more lignin under high salinity. RNA-seq and ChIP-seq assays reveal that SWO1 binds to the promoter of several cell wall-related genes and regulates their expression under saline conditions. Further study indicates that SWO1 interacts with importin ɑ IMPA1 and IMPA2, which are required for the import of nuclear-localized proteins. The impa1 impa2 double mutant also exhibits root growth inhibition under salt stress and mutations of these two genes aggravate the salt-hypersensitive phenotype of the swo1 mutant. Taken together, our data suggest that SWO1 functions together with importin ɑ to regulate the expression of cell wall-related genes, which enables plants to maintain cell wall integrity under high salinity.

Highlights

Soil salinity is one of the paramount factors that limit plant distribution, growth, and yield
The swo1 mutant exhibited root tip swelling under salt stress, which was largely caused by the disruption of cell wall integrity and increased accumulation of Reactive oxygen species (ROS)
Mutation in the SWO1 gene resulted in root cell swelling and reduced root elongation, and the cellulose and pectin contents were significantly reduced in the swo1 mutant under salt stress, suggesting that SWO1 is required for the maintenance of cell wall integrity under high salinity

Summary

Introduction

Soil salinity is one of the paramount factors that limit plant distribution, growth, and yield. SOS6, encoding a cellulose synthase-like protein, is involved in the regulation of root elongation under salt stress (Zhu et al, 2010). A recent study showed that the receptor-like kinase FER, together with the cell wall-localized leucine-rich repeat extensins LRX3, LRX4, and LRX5, and the secretory peptides RALFs, function as a module to monitor cell wall integrity and regulate salt tolerance in Arabidopsis (Zhao et al, 2018a). Loss of function of the MUR4 gene leads to a reduced root elongation and abnormal cell adhesion under high salinity (Zhao et al, 2019b). Together, all these data indicate that maintenance of cell wall integrity is critical for salt tolerance in plants. The molecular mechanisms underlying the regulation of cell wall biosynthesis under salt stress are still largely unknown

Methods

Results

Conclusion