Biochemical aspects of growth-stimulating effects of steroid phytohormones on lupine plants

Presowing treatment of seeds of lupine of various species and cultivars with brassinosteroids—homobrassinolide and epibrassinolide—caused an increase in protein content and a change in the proportion of some amino acids. Both hormones increased heterogeneity of high-and medium-molecular-weight nonhistone chromatin proteins but had no effect on the polypeptide profile of histones. Using epibrassinolide as an example, we showed that the brassinosteroid-induced increase in protein content in lupine seeds was due primarily to accumulation of the low-molecular-weight components of β-conglutin. The content of some amino acids in both α-and β-conglutins changed. These changes in protein metabolism correlated with an increase in the content of indoleacetic acid and a decrease in the content of abscisic acid.