The effects of Ascochyta blight (caused by Mycosphaerella pinodes) on changes in dry weight and in water, carbohydrate, nitrogen and free amino acid contents were studied in the leaf, the hull and the seeds on the second fructifer node of pea (Pisum sativum). Pea plants were grown in a glasshouse and inoculated with various concentrations of conidia at the beginning of seed filling, with uninoculated plants as controls. Disease induced a premature water loss of hulls and leaves, accelerated seed desiccation and reduced seed weight. Biochemical analyses revealed a decline in the carbohydrate content and a lower nitrogen remobilization in diseased leaves and hulls. Thus, Ascochyta blight alters carbohydrate metabolism, protein remobilization and free amino acid translocation from these organs. Disease also reduced carbohydrate and nitrogen content in seeds and, in case of high disease severity, the carbohydrate/nitrogen ratio in the seeds was also affected (seed protein concentration increased and starch concentration decreased).

The structure of protein bodies differs in the upper and lower parts of the cotyledons of mature seeds of Cytisus scoparius L. The palisade-mesophyll cells contain essentially homogeneous protein bodies, without globoids, but the protein bodies of the spongy-mesophyll cells are heterogeneous, with numerous globoids. Albumins, legumins and vicilins were selectively extracted from isolated protein bodies and their subunits separated by SDS-PAGE, under non-reducing and reducing conditions.

SUMMARYLeucine aminopeptidase from field beans was studied in the cotyledons of dry and germinating seeds. The partially purified enzyme had a molecular weight of about 60000 (determined by gel filtration). Activity was maximal at pH 75, with leucine-p-nitroanilide or leucine naphthylamide as substrates, and was stimulated by dithiothreitol and mercaptoethanol and inhibited by Cu and Zn ions. During germination, the highest enzyme activity in the cotyledons occurred after 2d.

Three enzymatic systems were analysed in Spartina alterniflora Loisel., S. maritima (Curt.) Fernald, and S. anglica C. E. Hubbard, using samples gathered in the west of France. Examination of the acid phosphatases, esterases, and superoxide dismutases demonstrates certain analogies found in the three species. The hypothesis of a hybrid origin for S. anglica remains probable and is indeed enhanced by the isoforms of the esterases.

The isolated protein bodies of Cytisus scoparius (L.) Link and Cytisus scoparius ssp. maritimus (Rouy) Heywood were observed by scanning electron microscopy; they showed comparable shapes and sizes. The protein content and the sub-unit composition ofthe fractionated albumins, vicilins and legumins, however, showed significant electrophoretic differences between the two plants, both at the qualitative and quantitative levels.