Atsushi Okazawa

Localization of storage carbohydrate planteose and identification of the planteose hydrolytic enzyme OmAGAL2 in seeds of Orobanche minor

Using MALDI-MS imaging, we visualized the localization of trisaccharide planteose in the dry seeds of Orobanche minor. Planteose was revealed to accumulate outside of the embryo, which supported the role of planteose as a storage carbohydrate. Since the first step of planteose is the hydrolysis of α-galactosyl linkage, we surveyed α-galactosidases in our transcriptome data. Among the three possible genes, the expression OmAGAL2 was increased in parallel with planteose decrease in germinating O. minor seeds. Heterologous expression of OmAGAL2 in E. coli confirmed the planteose hydrolytic activity of OmAGAL2. Additionally, subcellular localization analysis of OmAGAL2:mCherry revealed the secretion of OmAGAL2 to apoplasts. Taken together, it is suggested that planteose in the endosperm is hydrolyzed by OmAGAL2 in the apoplast around the embryo and provide hexoses required to promote germination. “Involvement of α-galactosidase OmAGAL2 in planteose hydrolysis during seed germination of Orobanche minor” JExpBot., erab527