Genome-Wide Association Study and Genomic Predictions for Hydroxycinnamate Concentrations in Maize Stover

Hydroxycinnamates, like ferulate (FA) and p-coumarate
(pCA), are important components of maize cell walls,
which influence pest resistance, ruminal digestibility, and biofuel
production. Increasing their concentration has been linked to increased
pest resistance, but also may lead to a decrease in nutritional value
or bioethanol production efficiency. Therefore, improving forage quality
or biofuel production without compromising plant resistance and a
thorough understanding of the biosynthesis and deposition of these
compounds is necessary, especially in stover, which is the feedstock
for second-generation biofuel production and determines animal forage
quality. This study aimed to identify genomic regions associated with
hydroxycinnamates and to develop genomic prediction models to determine
the best selection approach to modify hydroxycinnamate content. Although
heritability estimates for hydroxycinnamates were moderate, direct
phenotypic selection is discouraged because hydroxycinnamate quantification
is laborious and time-consuming. Negative genotypic correlations were
observed between animal digestibility and pCA content
and positive with diferulates content, suggesting differing effects
compared to previous studies on maize pith. However, no colocalizations
with digestibility QTLs were found, highlighting the need for further
research. Given the moderate predictive capacity of GBLUP prediction
models, genotypic selection is proposed as the most promising alternative
for modifying hydroxycinnamate content.