Diverging cell wall strategies for drought adaptation in two maize
inbreds with contrasting lodging resistance.
The plant cell wall is a plastic structure of variable composition that
constitutes the first line of defense against environmental challenges.
Lodging and drought are two stressful conditions that severely impact on
maize yield. In a previous work, we characterized the cell walls of two
maize inbreds susceptible (EA2024) or resistant (B73) to stalk-lodging.
Here, we show that drought induces phenotypical, physiological, cell
wall, and transcriptional changes with distinct dynamics in the two
inbreds, and that B73 is less tolerant than EA2024 to this stress. While
in control conditions, stalk of EA2024 had higher levels of cellulose,
uronic acids and p-coumarate than B73, upon drought these
displayed increased levels of arabinose-enriched polymers, such as
pectin-arabinans and arabinogalactan proteins, and a decreased lignin
content. By contrast, a deeper rearrangement of cell walls including the
modification of lignin composition and an increase of uronic acids was
observed in B73. Drought induced higher changes in gene expression in
B73 compared to EA2024, particularly in cell wall-related genes, that
were altered in an inbred-specific manner. Transcription factor
enrichment assays unveiled inbred-specific regulatory networks
coordinating cell wall genes expression. Altogether, these findings
reveal that B73 and EA2024 inbreds, with opposite stalk-lodging
phenotypes, undertake different cell wall modification strategies in
response to drought. We propose that the specific cell wall composition
that confers lodging resistance to B73 compromises its cell wall
plasticity and renders this inbred more susceptible to drought.