Análise Proteômica da Deposição de Proteínas em Sementes em Desenvolvimento e Suspensões Celulares Embriogênicas de Feijão-de-Corda [Vigna unguiculata (L.) Walp.]

Abstract

Cowpea (Vigna unguiculata) is a leguminous plant highly utilized by low-income earners of Northeastern Brazil. However, proteins found in the crop are highly deficient in sulfur-containing amino acids. In line with this, improvement of nutritional quality of cowpea seeds has been one of the major goals of breeding programs of the crop. A starting point in this respect is a concerted effort to study the basic biochemical and physiological aspects of the development of cowpea seed. Besides determining the protein deposition pattern during the development of zygotic embryos and somatic embryos of the species, we set out to identify genes with specific pattern of expression during the two processes which will be of immense importance in cowpea breeding. Using the technique of two-dimensional electrophoresis (2D-PAGE), we compared the protein deposition pattern of developing cowpea seeds with 10 days after anthesis (DAA) and mature seeds and embryogenic cell suspension (ECS). From each developmental stage and for ECS, we obtained proteomic reference maps that were highly reproducible within the pH of 3-10 and 4-7. Various spots were selected based on quantity or relative volume and rate of expression. About 800 (for seeds development) and 130 (for ECS) proteins spots up- or down-regulated, remained constantly expressed and were specific for each developmental stage. The spots were removed from the 2-D gels, processed, and subjected to mass spectrometry. Some strategies like peptide mass fingerprinting (PMF) and non-processed data search (MS/MS ion search) were employed for protein identification. Over 400 proteins in seeds and over 70 proteins in ECS were identified. A large number of these proteins were found to be primary metabolism proteins, energy, protein destination and storage and defense proteins and others related to stress.