Cell Wall Proteome Investigation of Bread Wheat (Triticum Aestivum) Developing Grain in Endosperm and Outer Layers

Abstract

The remodeling of cell wall polysaccharides is controlled by cell wall proteins (CWPs) during the development of wheat grain. This work describes for the first time the cell wall proteomes of the endosperm and outer layers of the wheat developing grain, which have distinct physiological functions and technological uses. Altogether 636 nonredundant predicted CWPs are identified with 337 proteins in the endosperm and 594 proteins in the outer layers, among which 295 proteins are present in both tissues, suggesting both common and tissue specific remodeling activities. These proteins are distributed into eight functional classes. Approximatively a quarter of them were predicted to act on cell wall polysaccharides, with many glycosylhydrolases and also expansin, lyases, and carbohydrate esterases. Therefore, these results provide crucial data to go further in the understanding of relationship between tissue‐specific morphogenesis and cell wall remodeling in cereals. Data are available via ProteomeXchange with identifier PXD010367.

Mining the Wheat Grain Proteome

“…A shorter method skipped the initial solubilisation to directly precipitate flour protein in cold acetone with or without trichloroacetic acid and resuspend it in urea [ 11 , 14 ]. A sucrose fractionation to isolate cell walls followed by solubilisation of the proteins in an acetate buffer with CaCl 2 or LiCl was employed to analyse the proteome of endosperm and outer layers of developing seeds [ 34 , 35 ]. A particularly complex method applying Tris/glycerol precipitation followed by urea resuspension of the pellet then reprecipitation in cold acetone and final redissolution in urea was performed to recover proteins from various wheat organs including maturing grains [ 36 ].…”

Cell Wall Proteome of Wheat Grain Endosperm and Outer Layers at Two Key Stages of Early Development

“…In addition, the outer tissues progressively began to degenerate (Figure 1). developmental stage [34]. More than 600 cell wall proteins (CWPs) were identified, half of which were present in both tissues, suggesting common and specific tissue remodeling activities.…”

“…Cell wall fractionation and CWPs extraction were performed as previously described [34]. Briefly, grain samples (500 mg) were ground and centrifuged in increasing sucrose concentrations to isolate cell walls.…”

“…Proteins (50 µg) were briefly separated in precast gels in order to reduce the mix complexity. Each track was cut into five fragments, which were reduced using dithiothreitol (DTT), alkylated by iodoacetamide and trypsinolyzed as previously described [34], prior to mass spectrometry (MS) analysis.…”

“…The identification and functional understanding of these protein actors are essential to gain access to cell wall dynamics. To date, only a few experiments have been reported on grass cell wall proteomes: Brachypodium distachyon [24][25][26], Saccharum spp (sugarcane) [27][28][29], Oryza sativa (rice) [30][31][32][33], and Triticum aestivum (wheat) [34]. Transcriptomic data on the developing wheat grain allowed for the identification of GH genes [15], and recently, we reported the first data on the cell wall proteome of endosperm and the outer layers of wheat grain at a given developmental stage [34].…”