Abstract

Adjacent plant cells are connected by specialized cell wall regions, called middle lamellae, which influence critical agricultural characteristics, including fruit ripening and organ abscission. Middle lamellae are enriched in pectin polysaccharides, specifically homogalacturonan (HG). Here, we identify a plant- specific Arabidopsis DUF1068 protein, called NKS1/ELMO4, that is required for middle lamellae integrity and cell adhesion. NKS1 localizes to the Golgi apparatus and loss of NKS1 results in changes to Golgi structure and function. The nks1 mutants also display HG deficient phenotypes, including reduced seedling growth, changes to cell wall composition, and tissue integrity defects. These phenotypes are comparable to qua1 and qua2 mutants, which are defective in HG biosynthesis. Notably, genetic interactions indicate that NKS1 and the QUAs work in a common pathway. Protein interaction analyses and modeling corroborate that they work together in a stable protein complex with other pectin- related proteins. We propose that NKS1 is an integral part of a large pectin synthesis protein complex and that proper function of this complex is important to support Golgi structure and function. Significance Cell walls are essential to cell morphogenesis, to protect plants against environmental stress, and for an array of products in our daily life. Understanding how plants produce cell wall polymers is therefore important. In this study, we outline how a family of unknown proteins function as a scaffold for key synthesis components of pectin, a central cell wall polymer. Our results thus define a robust pectin synthesis protein complex that is essential for the structure and function of Golgi and for plant tissue integrity. These results add critical information regarding pectin synthesis and cell wall metabolons.

Keywords

Arabidopsis; cell walls; cell biology; pectin; Golgi apparatus

Published in

Proceedings of the National Academy of Sciences of the United States of America
2024, Volume: 121, number: 15, article number: e2321759121
Publisher: NATL ACAD SCIENCES

SLU Authors

• Lathe, Rahul Shivanand

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    
  • Max Planck Institute for Molecular Plant Physiology
  • University of Copenhagen

• Noord, Niels

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Bhalerao, Rishikesh P.

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Cell Biology


Publication identifier

DOI: https://doi.org/10.1073/pnas.2321759121

Permanent link to this page (URI)

https://res.slu.se/id/publ/129961