Stärke‐ und Amylosesynthese in Samen von Mark‐ und Futtererbsen

Abstract

Abstract Starch and amylose synthesis in seeds of garden and field peas In seeds of garden and field peas (Pisum sativum, ssp. medullare and ssp. sativum) the synthesis of starch, amylose, amylopectin and sugar was investigated during seed development in plants differing in potassium nutrition. Seed growth started about 2 weeks after flowering and was terminated 5 weeks later.At the beginning of seed growth synthesis of amylose and amylopectin was very low in both pea species with a small surplus of amylopectin. After the first third of seed development, however, synthesis of amylose and mainly of amylopectin was improved at different rates. While both species exhibited an almost analogous increase in amylose synthesis, synthesis of amylopectin differed widely in garden and field peas. In garden peas it fell behind amylose production, yielding an amylose/amylopectin ratio of 2: 1 in mature seeds. In field peas amylopectin synthesis greatly exceeded amylose production resulting in an amylose/amylopectin ratio of 1:2.The 50 % higher starch content in seeds of field peas was mainly due to the more intensive rate of amylopectin synthesis. This shows that starch production via amylopectin synthesis is probably the more effective metabolic pathway.Sugar contents were highest in the middle of the generative phase. Until maturity they rapidly declined to one quarter of the maximum level. At each stage of seed development sugar content in garden peas was twice as high as in field peas. Potassium nutrition had only a very small influence on the carbohydrates examined.