Testa is involved in the control of storage mobilisation in seeds of Sesbania virgata (Cav.) Pers., a tropical legume tree from of the Atlantic Forest.

摘要

Seeds of Sesbania virgata (Cav.) Pers. (Leguminosae) contain galactomannan as a cell wall storage polysaccharide in the endosperm. After germination, it is hydrolysed by three enzymes: alpha -galactosidase (EC 3.2.1.22), endo- beta -mannanase (EC 3.2.1.78) and beta -mannosidase (EC 3.2.1.25). This work aimed at studying the role of the testa (seed coat) on galactomannan degradation during and after germination. Seeds were imbibed in water, with and without the testa, and used to evaluate the effect of this tissue on storage mobilization, as well as its possible role in the galactomannan hydrolases activities. Immunocytochemistry and immunodotblots were used to follow biochemical events by detecting and localising endo- beta -mannanase in different tissues of the seed. Endo- beta -mannanase and alpha -galactosidase activities were found in the testa and latter in the endosperm during galactomannan degradation. The former enzyme was immunologically detected in the testa, mainly during germination. The absence of the testa during imbibition led to the anticipation of protein mobilization and increased of the alpha -galactosidase activity and galactomannan degradation. Thus, the testa appears to play a role during storage mobilization in the legume seed of S. virgata probably by participating in the control of the production, modification and/or storage of the hydrolases.