Programmed cell death in soybean seed coats

• Published in: Plant science (Limerick) 2019-11, Vol.288, p.110232-110232, Article 110232
• Main Authors: Lemos Rocha, Gustavo, Pireda, Saulo, da Silva Araújo, Jucélia, Amâncio Oliveira, Antônia Elenir, Lima Tavares Machado, Olga, da Cunha, Maura, Grativol, Clicia, Valevski Sales Fernandes, Kátia
• Format: Article
• Language: English
• Subjects: Apoptosis; Caspase-like activity; Glycine max; Glycine max - enzymology; Glycine max - physiology; Metacaspase-like activity; Plant Proteins - metabolism; Programmed cell death; Seed coat; Seeds - physiology; Trypsin inhibitor
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2019.110232

•PCD-associated enzymes were found on seed coat of germinating soybean.•Radicle length of seeds germinated in presence of a pancaspase inhibitor was reduced.•Ultrastructural analysis showed absence of organelles in imbibed seed coats.•Oligonucleosome fragmentation was maximum at 72 h after imbibition. Seed coat is the tissue which establishes an interface between the seed inner tissues and external environment. Our group has shown that cowpea seed coat undergoes coordinated events of programmed cell death (PCD) during development. In relation to germinating seed coats, little is known on PCD events. The goal here was to investigate the biochemical aspects of germinating soybean seed coat, focusing on proteolytic activities related to PCD. In gel and in solution activity profiles of quiescent and germinating seed coat extracts revealed a complex pattern of caspase- and metacaspase-like cysteine protease activities. Trypsin inhibitor and reserve proteins were revealed as potential substrates for these proteases. A pancaspase inhibitor (z-VAD-CHO) affected the radicle length of seeds germinated under its presence. Ultrastructural analysis showed the absence of cell organelles in all seed coat layers after imbibition, while oligonucleosome fragments peaked at 72 h after imbibition (HAI). Altogether, the data suggest the presence of biochemical PCD hallmarks in germinating soybean seed coat and point to the involvement of the detected protease activities in processes such as reserve protein mobilization and weakening of seed coat.