TITLE:
Maize Development: Cell Wall Changes in Leaves and Sheaths
AUTHORS:
Ronald D. Hatfield, Jane M. Marita
KEYWORDS:
Maize, Cell Walls, Lignin, Phenolics, Structural Carbohydrates
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.8 No.6,
May
22,
2017
ABSTRACT: Developmental
changes occur in maize (Zea mays L.) as it transitions
from juvenile stages to the mature plant. Changes also occur as newly formed
cells mature into adult cells. Maize leaf blades including the midribs and
sheaths undergo cell wall changes as cells transition to fully mature cell
types. As is common in grasses during cell wall maturation, the lignin in the plant tissue is acylated with p-coumarates
(pCA).
This work characterizes cell walls in maize that make up leaf blade, leaf
midrib, and sheath tissues corresponding to tissue development. Maize plants
grown in the greenhouse were harvested; leaf, leaf midrib, and sheath tissues
from nodes 9 through 14 tissues were analyzed for cell wall composition. Cell
wall carbohydrates varied with the type of maize tissue, but there was little
change within a tissue type among the different nodes. Lignin concentrations
were lowest in the leaf blade (70 - 88 g·kg-1 CW)
followed by the sheath (123 - 140 g·kg-1 CW)
and highest in the midrib (140 - 168 g·kg-1 CW). Incorporation of pCA into cell walls paralleled the lignification.
Ferulates (FA) remained relatively constant as a proportion of the cell wall
(3.1 - 6.4 g·kg-1 CW)
across nodes and across all tissue types. The range of FA was 3.8 vs 5.7 g·kg-1 CW
averaged over all nodes with leaf blades being the lowest. Lignin composition
did not change significantly with cell wall maturation within a given tissue
type. The aerial portions of maize plants excluding the stem showed little
difference in cell wall composition along the different nodes. Higher levels of
ferulates were found in the sheath and leaf midrib compared to the leaf blade
tissues. Leaf midribs from the upper nodes of the plant contained the highest
levels of lignin. Perhaps a reflection of the function to keep leaves extended
and in an upward angle to help maximize photosynthetic capacity.