Protein bodies of the edible seeds of watermelon Citrullus vulgaris (Schrad.)

Seeds are the main source of proteins in human nutrition. Proteins in mature seeds exist in the form of protein bodies (PBs). These have been classified into three types : those with no inclusion ; those with globoid inclusions only ; and those with both globoid and crystalloid inclusions. We have observed that unfixed, the PBs of castor beans Ricinus communis L. Seeds appear in the microscope to contain only globoid inclusions. These same PBs when fixed have been described as having three components : a globulin crystalloid ; an amorphous matrix albumin ; and a globoid crystal of phytin. We have observed likewise that the PBs of unfixed watermelon seed cotyledons seemed to contain only globoid inclusion, whereas, in toluidine blue colored thin section of fixed cotyledons, we were able to distinguish crystalloids in addition to the globoids and amorphous matrix. Accordingly watermelon seed PBs should be classified among those containing the three components : globoid, crytalloid and amorphous matrix. Furthermore the PBs were observed to fill the greater portion of cotyledonary cell cavities suggesting that they are an interesting and cheap source of supplementary protein in the diet.