Proteins found during maturation and germination of seeds ofPhaseolus vulgaris L.

Seeds of the beanPhaseolus vulgaris L. (Veltruská Saxa cultivar) were gathered gradually at different stages of development, starting at fertilization up to full maturity. Seeds were freeze-dried and the dry solid used for preparing extracts which were analyzed by immunoelectrophoresis for the presence of proteins resembling those contained in the cotyledons of a mature seed. Proteins from cotyledons of the first stages of development of bean seedlings were analyzed similarly. After a preparatory period, approximately from the second—third seed development stage, there is a period of intense protein synthesis that characterizes cotyledons of a mature seed. These proteins increase in quantity and are differentiated in quality up to maturity when a single antiserum detected a total of 12. After germination both the quantity and number of these proteins decreases. It was found that some proteins are metabolically more active, both during synthesis and cleavage. This holds e.g. for phaseolin during maturation, as well as during germination. In addition, phaseolin changes its electrophoretic mobility, which is apparently due to proteolytic hydrolysis of phaseolin molecules. During the last phase of maturation, viz. dehydration of seeds, some new proteins suddenly appear, apparently synthesized from pre-formed peptide chains. In the discussion the possibility is taken up that the beginning on the synthesis of specific proteins characteristic for mature seeds is the cause underlying the disturbances in the embryonal development of distant hybrids.