Structure of Protochlorophyll‐containing Plastids in the Inner Seed Coat of Pumpkin Seeds (<i>Cucurbita pepo</i>)

Abstract

Abstract The inner seed coat of seeds of Cucurbita pepo L. cv. Ohlsens Enke Köks was used to study the development of protochlorophyll‐containing plastids with an abnormal ultrastructural composition. The pumpkins were harvested at different stages during fruit development and they thus contained seeds with different developmental stages. The dry weight of seeds of the developmental stages used varied from 0.04 g to 0.3 g. Such a series of seeds with decreasing water content indicating increasing maturity contained different amounts of protochlorophyll, from 0.20 μg/g fresh weight to 500 μg/g fresh weight. The ultrastructure of the protochlorophyll containing plastids changed greatly during development. In young seeds with a low content of protochlorophyll, regular prolamellar bodies were found and starch grains filled most of the plastids. During development the starch content decreased and the prolamellar bodies increased in size and lost their regularity. During maturation the plastids accumulated plastoglobuli, probably containing protochlorophyll, and finally the internal structure of the prolamellar body tubular complex was lost.