Abstract
Maize feeding value is strongly linked to plant digestibility. Cell wall composition and structure can partly explain cell wall digestibility variations, and we recently showed that tissue lignification and lignin spatial distribution also contribute to cell wall digestibility variations. Although the genetic determinism of digestibility and cell wall composition has been studied for more than 20 years, little is available concerning that of tissue lignification. Moreover, maize yield is negatively impacted by water deficit, and we newly highlighted the impact of water deficit on cell wall digestibility and composition together with tissue lignification. Consequently, the aim of this study was to explore the genetic mechanisms of lignin distribution in link with cell wall composition and digestibility under contrasted water regimes. Maize internodes from a recombinant inbred line (RIL) population grown in field trials with contrasting irrigation scenarios were biochemically and histologically quantified. Results obtained showed that biochemical and histological traits have different response thresholds to water deficit. Histological profiles were therefore only modified under pronounced water deficit, while most of the biochemical traits responded whatever the strength of the water deficit. Three main clusters of quantitative trait locus (QTL) for histological traits were detected. Interestingly, overlap between the biochemical and histological clusters is rare, and one noted especially colocalizations between histological QTL/clusters and QTL for p-coumaric acid content. These findings reinforce the suspected role of tissue p-coumaroylation for both the agronomic properties of plants as well as their digestibility.
Highlights
Maize is nowadays a staple food in the world (Shiferaw et al, 2011)
Parental lines F271 and Cm484 were cultivated in one plot each
Under the I condition, plant height and biomass yield were higher in F271 than in Cm484 in both 2014 and 2015 (Supplementary Table S2)
Summary
Maize is nowadays a staple food in the world (Shiferaw et al, 2011). It provides carbohydrates, proteins, lipids, and vitamins for billions of people and serves as an important energy resource for animal feed and biorefinery processes (Virlouvet et al, 2019). A non-lethal and cost-effective method has been proposed by puncture test (Seegmiller et al, 2020) to quantify rind thickness and stalk diameter on poison hemlock (Conium maculatum). FASGA (abbreviation of Spanish names of fucsina, alcian blue, safranina, glicerina, and aqua) staining of internode cross sections (Tolivia and Tolivia, 1987) is a powerful approach that allows to distinguish highly lignified tissues and poorly lignified tissues. It was recently applied in sorghum (Perrier et al, 2017) and maize (El Hage et al, 2018; Vo et al, 2020) cross sections. The advent of several plugins (Zhang et al, 2013; Legland et al, 2017) is allowing quantification of anatomical features from FASGA-stained cross sections, increasing the throughput of data analysis
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