Root and vascular tissue-specific expression of glycine-rich protein AtGRP9 and its interaction with AtCAD5, a cinnamyl alcohol dehydrogenase, in Arabidopsis thaliana

Abstract

The vascular tissue of roots performs essential roles in the physical support and transport of water, nutrients, and signaling molecules in higher plants. The molecular mechanisms underlying the function of root vascular tissue are poorly understood. In this study, we analyzed the expression pattern of AtGRP9, a salt stress-responsive gene encoding a glycine-rich protein, and its interacting partner, in Arabidopsis thaliana. Analysis of GUS or GFP expression under the control of the AtGRP9 promoter showed that AtGRP9 was expressed in the vascular tissue of the root; subcellular localization analysis further demonstrated that AtGRP9 proteins were localized in the cell wall and in the cytoplasm. Yeast two-hybrid analysis revealed that AtGRP9 interacted with AtCAD5, a major cinnamyl alcohol dehydrogenase (CAD) involved in lignin biosynthesis, for which tissue-specific distribution was comparable with that of AtGRP9. These results suggest that AtGRP9 may be involved in lignin synthesis in response to salt stress as a result of its interaction with AtCAD5 in A. thaliana.

The structure, function, and biosynthesis of plant cell wall pectic polysaccharides

“…116 GRPs are hypothesized to interact with components of signaling pathways, and thus, may be regulators of wall structure. 117,118 WAKs have been implicated in cell elongation, morphogenesis, 119,120 and defense against pathogens. 121,122 Undoubtedly, wall-associated proteins serve complex and biological roles with regard to wall structure.…”

Functional diversity of the plant glycine-rich proteins superfamily

“…These results suggest the involvement of this Class I GRP in lignin biosynthesis and/or deposition. 13 Interestingly, another GRP that belongs to a different class is also involved in cell wall structure. The Class II GRP from tobacco NtCIG1 presents a structural role.…”

Comprehensive multiphase NMR: a promising technology to study plants in their native state

“…The pentaglycine may have been derived from glycine-rich proteins (GRPs) that are present as structural components of the cell wall. [42,43] GRPs are small (~100 amino acid residues), as are most signal peptide preproteins. [44] Fragments of GRPs may induce lignification by binding to cell wall receptors, which would be consistent with the previous findings that fragments of other cell wall components, such as pectin, do the same.…”