Corn, like other grasses, is a monocot- the seed has a single cotyledon as part of the embryo. Unlike the dicot species, such as soybeans, in which the two cotyledons emerge and photosynthesize, the corn cotyledon remains underground. The shape of this thin structure led to the name scutellum, which is latin for ‘small shield’. It attaches to the rest of the embryo by a small channel with vascular tissue and is positioned between the shoot-root portions and the endosperm. The scutellum has its own enzymes that are activated with imbibition to digest the starch and oils stored in the scutellum as well as assist in the movement of sugars from the endosperm.
The scutellum is a storage location although much smaller than the endosperm. Efforts to select for high oil corn, carried on for many years at the University of Illinois, resulted in larger scutellum for more storage of oils, and smaller endosperm. Other parts of the embryo also were larger in high oil corn seeds as compared to the original ‘normal’ varieties before selections. Having a carbohydrate storage capacity and having a vascular connection with the shoot and root parts of the embryo makes it a target for infection by pathogens. This connection has been utilized by scientists to transmit trait DNA via infection by the symbiotic bacterium Agrobacterium tumefaciens carrying the DNA into the scutellum when excised from the embryo. Activity in the scutellum is turned on with imbibition as germination begins.
About Corn Journal
The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.