Phytolith Content Negatively Affects Forage Quality of Eragrostis curvula (Schrad.) Nees

Phytoliths are intra and extracellular siliceous deposits present in different plant tissues. Si uptake and transport are mediated by Lsi genes and its concentration is associated with forage quality. Our objective was to determine the phytolith content in seven Eragrostis curvula genotypes at the outbreak and re-growth stages to assess its relationship with the forage quality parameters and perform a genome-wide analysis to detect the presence/absence of Lsi genes. The mean values of the phytolith content of dry matter varied between 1.94–2.26% and 2.72–4.71% at the outbreak and re-growth stages, respectively, with highly significant differences among the genotypes and phenological stages. A highly negative correlation was observed in the phytolith content and in vitro dry matter digestibility and crude protein, revealing its importance as a selection parameter in breeding programs. A positive correlation was obtained between the phytolith content and lignin, neutral detergent fiber, and acid detergent fiber. The main morphotypes of the phytoliths included saddle-shaped, bulliform, and acicular cells. Genes Lsi1, Lsi2, Lsi3, and Lsi6, previously reported in silica uptake, were identified and compared with related species, being the gene sequences highly conserved, meaning that its accumulation is probably due to differences in the gene expression or different allelic variants among cultivars.