Environmentally-induced changes in protein composition in developing grains of wheat are related to changes in total protein content

Abstract

Nitrogen (N) nutrition, post-anthesis temperature and drought-induced changes in the kinetics of accumulation of dry mass, total grain N and protein fractions (albumins-globulins, amphiphils, gliadins, and glutenins) contents were examined for winter wheat (Triticum aestivum L.). Crops were grown in controlled environment tunnels in 1994 and 1998. In 1994, five post-anthesis temperatures averaging from 15-25 degrees C were applied during grain-filling. In 1998 two post-anthesis temperatures averaging 13 degrees C and 20 degrees C were applied and factorized with two post-anthesis water regimes. In 1994 crops also were grown in the field, where different application rates and timing of N nutrition were tested. When expressed in thermal time, the kinetics of accumulation of the protein fractions were not significantly affected by post-anthesis temperature or drought; whereas N nutrition significantly increased the rate and duration of accumulation of storage proteins. Albumin-globulin proteins accumulated during the early stage of grain development. The rate of accumulation of that fraction decreased significantly at c. 250 degrees Cd after anthesis, when the storage proteins (gliadins and glutenins) started to accumulate significantly. Single allometric relationships for the different environmental conditions exist between the quantity of each protein fraction and the total quantity of N per grain. From these results it was concluded that (1) the process of N partitioning is neither significantly affected by post-anthesis temperature or drought nor by the rate and timing of N nutrition and (2) at maturity, variations in protein fraction composition are mainly because of differences in the total quantity of N accumulated during grain-filling.

The Variation of β-amylase Activity and Protein Fractions in Barley Grains as Affected by Genotypes and Post-anthesis Temperatures

“…However, the enhanced β-amylase activity under high temperature was associated with the decrease of grain weight and it may be assumed that the increase in β-amylase activity will not improve malting quality, as protein content is also increased simultaneously and starch accumulation is reduced in mature grains. In wheat, it was found that structural/ metabolic protein fractions accumulate mainly during the early phase of grain growth, when most endosperm cells are still dividing, whereas the accumulation of storage protein fractions appears later in grain development, when cell division has stopped 30 . In the current study, it was found that albumins were the least affected and glutelins was the most affected protein fraction when the plants were exposed to high temperature during grain development, suggesting that albumins are mainly synthesized in the early period of the grain filling stage and glutelins, mainly a storage protein, occur later.…”

Quality of winter wheat in relation to heat and drought shock after anthesis

“…Although albumins-globulins have only a slight influence on the dough quality, they are important from the nutritional point of view, due to their high contents of essential amino acids. Gupta et al (1992) and Triboï et al (2003) reported an increase in the gliadin proportion and a reduction in the glutenin proportion as the protein content of the flour increased. The ratio of albumins-globulins did not increase proportionately with the protein content in response to a rise in temperature (Gupta et al 1992;Wieser & Seilemeier 1998;Triboï et al 2003).…”

“…Gupta et al (1992) and Triboï et al (2003) reported an increase in the gliadin proportion and a reduction in the glutenin proportion as the protein content of the flour increased. The ratio of albumins-globulins did not increase proportionately with the protein content in response to a rise in temperature (Gupta et al 1992;Wieser & Seilemeier 1998;Triboï et al 2003). It was demonstrated by Zhao et al (2009) that protein components are very sensitive to drought stress during the later phenophases of grain-filling.…”

Parcelamento e fontes de nitrogênio na qualidade fisiológica de sementes de trigo

“…No entanto, a constituição genética da cultivar e sua interação com o ambiente em que foi originada, podem afetar o percentual de germinação das sementes (DODD & DONOVAN 1999), principalmente devido as mudanças na organização estrutural e síntese proteica no momento da germinação do embrião (RAMAGOPAL 1990). Em nível fisiológico, a formação de proteínas, importantes no processo de germinação das sementes, envolve mecanismos de absorção de nitrogênio pelas raízes, acúmulo nos órgãos vegetativos e posterior remobilização para os grãos para a formação e configuração proteica (TRIBOÏ et al 2003). Este nitrogênio remobilizado é responsável por cerca de 80% do conteúdo total do nutriente no grão (SUPRAYOGI et al 2011 e aproveitamento deste nutriente.…”