Premium
Effects of the embryonic axis and phytohormones on proteolysis of the storage protein in buckwheat seed
Author(s) -
Dunaevsky Yakov E.,
Belozersky Mikhail A.
Publication year - 1993
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1993.tb01760.x
Subject(s) - proteolysis , storage protein , biochemistry , biology , seedling , cycloheximide , hydrolysis , incubation , globulin , chemistry , enzyme , protein biosynthesis , botany , gene , immunology
The role of the embryonic axis in regulation of proteolysis of the main storage protein was studied in buckwheat ( Fagopyrum esculentum ) seed. Polyacrylamide gel electrophoresis (PAGE) analysis revealed that removal of the embryonic axis had no effect on the first stage of hydrolysis, that is proteolytic modification, of 13S globulin. This modification took place in the growing seedlings also in the presence of cycloheximide, i.e. it was due to an enzyme present in dry seed. However, in isolated cotyledons the 13S globulin was not degraded completely. Incubation of isolated cotyledons with cytokinins, gibberellic acid and indoleacetic acid could not replace the excised embryonic axis. At the same time, proteolysis of the 13S globulin in the growing seedlings was strongly inhibited by casein hydrolyzate. It is suggested that a complete proteolysis of the modified storage protein is regulated by the concentration of hydrolysis products at the site of hydrolysis. The embryonic axis serves, most probably, as a site of efflux of the products of protein hydrolysis in the cotyledons during seedling growth and thus regulates the course of proteolysis. Abscisic acid (10–100 μ M ) was without effect on modification of the 13S globulin, but suppressed the complete proteolysis of the protein by inhibiting, apparently, the synthesis of the cysteine proteinase in the growing seedlings.