Expressão diferencial de proteínas em embriões de linhagens de milho pipoca (Zea mays L.) com elevada e baixa capacidade de expansão

Abstract

The purpose of this work was to conduct a study on the differential expression of proteins in two different lines of popcorn, one of them with high expansion capacity (P11) and one with low expansion capacity (P16), through the Shotgun proteomics approach. A total of 1,189 proteins were identified expressed in embryos that mostly presented catalytic activity as their molecular function, and that largely constitute cellular components of the cytoplasm and cell membranes. Functional annotations revealed 103 different biological functions, allocated into 26 major functional groups, where proteins linked to functions of metabolic processes stand out. Analysis of these proteins in metabolic pathways revealed that the great majority correspond to metabolic pathways of carbohydrates, amino acids and of biosynthesis. The differential expression of these protein, during the process of embryogenesis between lines, revealed that 4, 127 and 30 proteins decreased expression in line P11, P16 and both, respectively. On line P11, there was a decrease in protein expression of the metabolic protein pathway. On the other hand, line P16 showed decreased expression of proteins related to the metabolism of DNA, RNA, proteins and tricarboxylic acid cycle. Proteins that decreased their expression in both lines also show functions related to the metabolism of proteins, DNA, carbon and fatty acids. It was observed that 9, 7 and 34 proteins increased their expression on line P11, P16 and both, respectively. Among proteins that exhibited increased expression are: storage proteins (vicilin, oleosin), proteins that accumulate as the embryogenesis process advances (embryonic protein, late embryogenesis abundant protein), transport proteins (protein and lipids), carbon metabolism and fatty acids. Given that in embryos the metabolic pathway of lipids is important to provide synthesis and storage for itself, through searches performed on Kregg - Search & Colors Pathways, It was possible to observe that 18 proteins are associated to the metabolic pathway of lipids. Two isoforms of enoyl-reductase were found decreasing their expression in line P16 when compared to P11. Although the identification of proteins linked to expansion capacity has not been consistent, this study provides important directions for further analysis of differential proteome in embryo, endosperm and the pericarp of popcorn kernels, which along with a chemical assessment of seed components will enable important advances in genetic improvement programs for this crop.