Starch synthesis in shriveled and plump triticale seeds.

Seven lines of triticale (X Triticosecale Wittmack) with either shriveled or plump seed characteristics were planted in the field, and seed developmental changes in weight, starch content, the activity of starch biosynthetic and degradative enzymes, and ATP content were studied in three consecutive years in Oregon. Experimental results varied among genotypes and with growing environment, but overall indicated that: (a) amylase activity was higher in shriveled lines, but was not directly synchronized with the occurrence of shriveling at later stages of seed formation; (b) ADP-glucose starch synthase contributed to starch accumulation in triticale, but it appeared not to be associated with shriveledness as no stage-related changes were observed; and (c) ADP-glucose pyrophosphorylase activity was 2- to 3-fold higher in plump lines than that of shriveled lines, indicating that this enzyme may play an important role in the degree of plumpness or stach accumulation of triticale seeds.