The Structure of Seeds and Their Food Reserves

Abstract

Chapter 2. The Structure of Seeds and Their Food Reserves Seed StructureIn this chapter we will survey the major features of seed structure which should be understood in order to appreciate points raised in subsequent chapters. Detailed accounts of seed structure can be found in works on plant anatomy and morphology as well as in recently published studies [I, 7]. We will, however, give special, detailed attention to the food reserves of seeds, the site of accumulation of which is obviously closely associated with structure.The seed is derived from the fertilized ovule. In almost all cases the following can be recognized as the fertilized ovule develops: (1) the testa -the product of one or both integuments of the ovule; (2) the perisperm -derived from the nucellus; (3) the endosperm -produced as a result of fusion between one male generative nucleus and the two polar nuclei to form the triploid endosperm nucleus 1 ; (4) the embryo -the result of fertilization of the oosphere (ovum) by a male nucleus. The degree to which these various components continue their development or even whether or not they are all retained, leads to some of the fund'amental structural differences among various types of seed (Fig. 2.1). In addition, in many species extra-ovular tissue, especially the ovary wall (pericarp), becomes closely associated with the seed during its formation. We should also note the variability in structure even in seeds produced by one plant, i.e. seed polymorphism. Variations in size, presence or absence of endosperm, colour of testa, and amounts of chlorophyll can be found in several species. The factors responsible for producing these differences are incompletely understood.It is necessary only to remind the reader of the great range in size and shape of seeds, from the spore-like seeds of the Orchids, through the familiar seeds of crop plants (peas, beans, cereals, lettuce, tomato) to the large coconut and huge Lodoicea which may weigh up to 15 kg! The TestaThe" endosperm" of Gymnosperm seeds is haploid megagametophytic tissue.

Influence of Lipids with and without Other Cottonseed Reserve Materials on Aflatoxin B1 Production by Aspergillus flavus

“…Cottonseed contains 39% protein by weight, and most occurs as the globulin family of seed storage proteins (Bewley and Black, 1978). In addition, this oilseed contains 33% lipid by weight (Bewley and Black, 1978), with triglycerides predominant (96-98% of total lipid) (Jones and King, 1990). Cottonseed also contains up to 10%, by weight, of the storage trisaccharide raffinose (Muller and Jacks, 1983).…”

Raffinose content may influence cottonseed susceptibility to aflatoxin contamination

“…Cottonseed storage protein (CSP), a globulin, is localized in developing and mature cotyledons. Cottonseed contains 39% protein by weight with most predominantly present as globulin seed storage proteins (1). Cottonseed also contains up to 10% by weight of the storage trisaccharide raffinose (2).…”

α-galactosidase activity in ingested seeds and in the midgut ofDysdercus peruvianus (Hemiptera: Pyrrhocoridae)

“…Cotton seeds are a good example of a general rule observed in storage reserve in seeds; that is, as the content of lipids increases, there is a concomitant decrease in starch content (Bewley and Black, 1978). Cotton seeds are particularly rich in sugars, especially in sugars of the raffinose family oligosaccharides, mainly the trisaccharide raffinose (galactosyl sucrose) and the tetrasaccharide stachyose (digalactosyl sucrose).…”