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

Abstract

The cell wall is an important compartment in grain cells that fulfills both structural and functional roles. It has a dynamic structure that is constantly modified during development and in response to biotic and abiotic stresses. Non-structural cell wall proteins (CWPs) are key players in the remodeling of the cell wall during events that punctuate the plant life. Here, a subcellular and quantitative proteomic approach was carried out to identify CWPs possibly involved in changes in cell wall metabolism at two key stages of wheat grain development: the end of the cellularization step and the beginning of storage accumulation. Endosperm and outer layers of wheat grain were analyzed separately as they have different origins (maternal and seed) and functions in grains. Altogether, 734 proteins with predicted signal peptides were identified (CWPs). Functional annotation of CWPs pointed out a large number of proteins potentially involved in cell wall polysaccharide remodeling. In the grain outer layers, numerous proteins involved in cutin formation or lignin polymerization were found, while an unexpected abundance of proteins annotated as plant invertase/pectin methyl esterase inhibitors were identified in the endosperm. In addition, numerous CWPs were accumulating in the endosperm at the grain filling stage, thus revealing strong metabolic activities in the cell wall during endosperm cell differentiation, while protein accumulation was more intense at the earlier stage of development in outer layers. Altogether, our work gives important information on cell wall metabolism during early grain development in both parts of the grain, namely the endosperm and outer layers. The wheat cell wall proteome is the largest cell wall proteome of a monocot species found so far.

Genome-wide association mapping for component traits of drought and heat tolerance in wheat

“…Markers such as AX-94578563 and AX-94941121 associated with DH were present near the gene coding for Invertase/pectin methylesterase inhibitor domain superfamily and sugar-1-phosphate guanyl transferase, respectively. The first has a role in early development of wheat grain endosperm and outer layers (Mehdi et al, 2020 ), which is related to flowering fertilization in flowering plants. Whereas the second one has a role in L-galactose guanyl-transferase, which increases leaf ascorbate content that induces early flowering (Laing et al, 2007 ).…”

Spatial distribution of proteins and metabolites in developing wheat grain and their differential regulatory response during the grain filling process

“…Interestingly, in this study, we identified seven expansin protein isoforms that significantly accumulated only in the cavity fluid. Expansins could be specifically involved in grain enlargement and seed growth control (Mehdi et al., 2020 ). The functional mechanism of expansin involves disrupting hydrogen bonds between cellulose microfibrils and cross‐linking glycans in the cell wall, permitting turgor‐driven cell wall extension (Mcqueenmason and Cosgrove, 1994 ; Mcqueenmason and Cosgrove, 1995 ).…”

Overexpression of DUF538 from Wild Arachis Enhances Plant Resistance to Meloidogyne spp.

“…Within this large family, DUF538 superfamily members are among the most studied proteins, found in more than 40 plant species, almost exclusively in Embryophyta [4]. Changes in DUF538 gene expression behavior and protein abundance were observed during different plant developmental and reproductive stages [5][6][7] and in response to various abiotic stresses, including drought [8]; high temperature [9]; carbohydrate deprivation [10]; and nitrogen toxicity [11]. DUF538 protein was also reported to be involved in intracellular transport of cuticular waxes, affecting leaf surface permeability and water loss control [12].…”