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Distribution of gluten proteins in bread wheat (Triticum aestivum) grain.

ABSTRACT: BACKGROUND AND AIMS:Gluten proteins are the major storage protein fraction in the mature wheat grain. They are restricted to the starchy endosperm, which forms white flour on milling, and interact during grain development to form large polymers which form a continuous proteinaceous network when flour is mixed with water to give dough. This network confers viscosity and elasticity to the dough, enabling the production of leavened products. The starchy endosperm is not a homogeneous tissue and quantitative and qualitative gradients exist for the major components: protein, starch and cell wall polysaccharides. Gradients in protein content and composition are the most evident and are of particular interest because of the major role played by the gluten proteins in determining grain processing quality. METHODS:Protein gradients in the starchy endosperm were investigated using antibodies for specific gluten protein types for immunolocalization in developing grains and for western blot analysis of protein extracts from flour fractions obtained by sequential abrasion (pearling) to prepare tissue layers. KEY RESULTS:Differential patterns of distribution were found for the high-molecular-weight subunits of glutenin (HMW-GS) and ?-gliadins when compared with the low-molecular-weight subunits of glutenin (LMW-GS), ?- and ?-gliadins. The first two types of gluten protein are more abundant in the inner endosperm layers and the latter more abundant in the subaleurone. Immunolocalization also showed that segregation of gluten proteins occurs both between and within protein bodies during protein deposition and may still be retained in the mature grain. CONCLUSIONS:Quantitative and qualitative gradients in gluten protein composition are established during grain development. These gradients may be due to the origin of subaleurone cells, which unlike other starchy endosperm cells derive from the re-differentiation of aleurone cells, but could also result from the action of specific regulatory signals produced by the maternal tissue on specific domains of the gluten protein gene promoters.

SUBMITTER: Tosi P

PROVIDER: S-EPMC3119610 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

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Distribution of gluten proteins in bread wheat (Triticum aestivum) grain.

Tosi Paola P Gritsch Cristina Sanchis CS He Jibin J Shewry Peter R PR

Annals of botany 20110701 1

<h4>Background and aims</h4>Gluten proteins are the major storage protein fraction in the mature wheat grain. They are restricted to the starchy endosperm, which forms white flour on milling, and interact during grain development to form large polymers which form a continuous proteinaceous network when flour is mixed with water to give dough. This network confers viscosity and elasticity to the dough, enabling the production of leavened products. The starchy endosperm is not a homogeneous tissue ...[more]

PMID: 21693664

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Project description:BACKGROUND:High post-anthesis (p.a) temperatures reduce mature grain weights in wheat and other cereals. However, the causes of this reduction are not entirely known. Control of grain expansion by the maternally derived pericarp of the grain has previously been suggested, although this interaction has not been investigated under high p.a. temperatures. Down-regulation of pericarp localised genes that regulate cell wall expansion under high p.a. temperatures may limit expansion of the encapsulated endosperm due to a loss of plasticity in the pericarp, reducing mature grain weight. Here the effect of high p.a. temperatures on the transcriptome of the pericarp and endosperm of the wheat grain during early grain-filling was investigated via RNA-Seq and is discussed alongside grain moisture dynamics during early grain development and mature grain weight. RESULTS:High p.a. temperatures applied from 6-days after anthesis (daa) and until 18daa reduced the grain's ability to accumulate water, with total grain moisture and percentage grain moisture content being significantly reduced from 14daa onwards. Mature grain weight was also significantly reduced by the same high p.a. temperatures applied from 6daa for 4-days or more, in a separate experiment. Comparison of our RNA-Seq data from whole grains, with existing data sets from isolated pericarp and endosperm tissues enabled the identification of subsets of genes whose expression was significantly affected by high p.a. temperature and predominantly expressed in either tissue. Hierarchical clustering and gene ontology analysis resulted in the identification of a number of genes implicated in the regulation of cell wall expansion, predominantly expressed in the pericarp and significantly down-regulated under high p.a. temperatures, including endoglucanase, xyloglucan endotransglycosylases and a ?-expansin. An over-representation of genes involved in the 'cuticle development' functional pathway that were expressed in the pericarp and affected by high p.a. temperatures was also observed. CONCLUSIONS:High p.a. temperature induced down-regulation of genes involved in regulating pericarp cell wall expansion. This concomitant down-regulation with a reduction in total grain moisture content and grain weight following the same treatment period, adds support to the theory that high p.a. temperatures may cause a reduction in mature grain weight as result of decreased pericarp cell wall expansion.

Project description:BACKGROUND: Grain texture is one of the most important characteristics in bread wheat (Triticum aestivum L.). Puroindoline-D1 genes play the main role in controlling grain texture and are intimately associated with the milling and processing qualities in bread wheat. RESULTS: A series of diagnostic molecular markers and dCAPS markers were used to characterize Pina-D1 and Pinb-D1 in 493 wheat cultivars from diverse geographic locations. A primer walking strategy was used to characterize PINA-null alleles at the DNA level. Results indicated that Chinese landraces encompassing 12 different Puroindoline-D1 allelic combinations showed the highest diversity, while CIMMYT wheat cultivars containing 3 different Puroindoline-D1 allelic combinations showed the lowest diversity amongst wheat cultivars from the five countries surveyed. Two novel Pina-D1 alleles, designated Pina-D1s with a 4,422-bp deletion and Pina-D1u with a 6,460-bp deletion in the Ha (Hardness) locus, were characterized at the DNA level by a primer walking strategy, and corresponding molecular markers Pina-N3 and Pina-N4 were developed for straightforward identification of the Pina-D1s and Pina-D1u alleles. Analysis of the association of Puroindoline-D1 alleles with grain texture indicated that wheat cultivars with Pina-null/Pinb-null allele, possessing an approximate 33-kb deletion in the Ha locus, have the highest SKCS hardness index amongst the different genotypes used in this study. Moreover, wheat cultivars with the PINA-null allele have significantly higher SKCS hardness index than those of Pinb-D1b and Pinb-D1p alleles. CONCLUSIONS: Molecular characterization of the Puroindoline-D1 allele was investigated in bread wheat cultivars from five geographic regions, resulting in the discovery of two new alleles - Pina-D1s and Pina-D1u. Molecular markers were developed for both alleles. Analysis of the association of the Puroindoline-D1 alleles with grain texture showed that cultivars with PINA-null allele possessed relatively high SKCS hardness index. This study can provide useful information for the improvement of wheat quality, as well as give a deeper understanding of the molecular and genetic processes controlling grain texture in bread wheat.

Project description:BackgroundThe analyses of protein synthesis, accumulation and regulation during grain development in wheat are more complex because of its larger genome size compared to model plants such as Arabidopsis and rice. In this study, grains from two wheat cultivars Jimai 20 and Zhoumai 16 with different gluten quality properties were harvested at five development stages, and were used to displayed variable expression patterns of grain proteins.ResultsProteome characterization during grain development in Chinese bread wheat cultivars Jimai 20 and Zhoumai 16 with different quality properties was investigated by 2-DE and tandem MALDI-TOF/TOF-MS. Identification of 117 differentially accumulated protein spots representing 82 unique proteins and five main expression patterns enabled a chronological description of wheat grain formation. Significant proteome expression differences between the two cultivars were found; these included 14 protein spots that accumulated in both cultivars but with different patterns and 27 cultivar-different spots. Among the cultivar-different protein spots, 14 accumulated in higher abundance in Jimai 20 than in Zhoumai 16, and included NAD-dependent isocitrate dehydrogenase, triticin precursor, LMW-s glutenin subunit and replication factor C-like protein. These proteins are likely to be associated with superior gluten quality. In addition, some proteins such as class II chitinase and peroxidase 1 with isoforms in developing grains were shown to be phosphorylated by Pro-Q Diamond staining and phosphorprotein site prediction. Phosphorylation could have important roles in wheat grain development. qRT-PCR analysis demonstrated that transcriptional and translational expression patterns of many genes were significantly different.ConclusionsWheat grain proteins displayed variable expression patterns at different developmental stages and a considerable number of protein spots showed differential accumulation between two cultivars. Differences in seed storage proteins were considered to be related to different quality performance of the flour from these wheat cultivars. Some proteins with isoforms were phosphorylated, and this may reflect their importance in grain development. Our results provide new insights into proteome characterization during grain development in different wheat genotypes.

Dataset Information

Distribution of gluten proteins in bread wheat (Triticum aestivum) grain.

Publications

Distribution of gluten proteins in bread wheat (Triticum aestivum) grain.

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