Maize
Maize, Zea mays, also known as corn, is one of the most widely grown and widely eaten crops. It is a grass that forms large ears full of kernels, which are familiar as sweetcorn when eaten in the un-ripe form and popcorn when roasted in a pan.
Maize is thought to have originated in Mexico and played an important role in Mayan culture as mythology often revolved around a maize god.
In the United States over 80% of all maize grown is genetically modified to provide mainly insect resistance.
One such pest, are caterpillars of the European corn borer moth, which were first reported in the US in 1917 and cause a huge amount of damage to maize crops and economic loss. GM maize containing a gene from a bacteria called Bacillus thuringiensis allows the crop to produce a protien that is toxic to insects.
The root system of maize plants and other grasses typically form a fibrous structure of multiple seminal roots. You can see the seminal roots in this scan of a young maize plant. In older plants, the roots develop from the stem, known as crown or brace roots, become the predominant part of the root system and are responsible for most of the water and nutrient uptake.
3D Root Architecture
This video of a very young maize plant shows its growth after 14 days with both the root and stem emerging from the maize kernel. Very quickly a primary root is sent down and is supported by many lateral roots branching off from this initial root. These are then followed by the seminal roots and crown roots above the kernel as the root system develops into a more complex system.
Root Anatomy
The cross section was through a maize crown root acquired using a confocal microscope.
Root anatomy reveals a central area known as the stele. This area contains Metaxylem vessels which are surrounded by Xylem (orange/red) which transport water and nutrients, and phloem (blue) that transport sugars and hormones.
The stele is surrounded by a layer of endodermis (red) and then several layers of cortical cells (cyan) which contain airspaces termed aerenchyma.
The pen/ultimate ring of outer cells, known as the exodermis (red) and epidermis (blue), function to retain water and form root hairs for nutrient uptake.