Reassessment of the pits and antipits in soybean seeds

Abstract

A soybean (Glycine max (L.) Merr.) cotyledon has a concave region on its abaxial center called a pit, and the seed coat has a corresponding convex region on its inner surface called an antipit. While it is clear that the pit is lined with large epidermal cells, the anatomical identity of the antipit has been a subject of confusion. The inner surface of the seed coat consists of a compressed endosperm tissue that is subtended by an aleurone layer. In the antipit region of the seed coat, additional endosperm cells are situated between the aleurone layer and the compressed endosperm tissue. These endosperm cells, called cone cells, are similar to ordinary aleurone cells in basic structure. In the present study, it is demonstrated that the surface ornamentations of the antipit are a print of the pit on the compressed endosperm tissue. The functional aspects of the antipit–pit complex are not known. It was previously postulated that the antipit–pit region has an enhanced capability of nutrient translocation to the growing embryo, but there is little evidence to support this hypothesis. Alternatively, the antipit–pit association may provide a structural feature that anchors the embryo within the seed coat while contributing to an overall spherical shape of the seed.Key words: antipit, endosperm, Glycine max, pit, seed coat, soybean.