Anthocyanin is a natural pigment that has a functional role in plants to attract pollinating insects and is important in stress response. Foxtail millet (Setaria italica) is known as a nutritional crop with high resistance to drought and barren. However, the molecular mechanism regulating anthocyanin accumulation and the relationship between anthocyanin and the stress resistance of foxtail millet remains obscure. In this study, we screened hundreds of germplasm resources and obtained several varieties with purple plants in foxtail millet. By studying the purple-leaved B100 variety and the control variety, Yugu1 with green leaves, we found that B100 could accumulate a large amount of anthocyanin in the leaf epiderma, and B100 had stronger stress tolerance. Further transcriptome analysis revealed the differences in gene expression patterns between the two varieties. We identified nine genes encoding enzymes related to anthocyanin biosynthesis using quantitative PCR validation that showed significantly higher expression levels in B100 than Yugu1. The results of this study lay the foundation for the analysis of the molecular mechanism of anthocyanin accumulation in foxtail millet, and provided genetic resources for the molecular breeding of crops with high anthocyanin content.

Anthocyanin is a class of water-soluble pigments with antioxidant activity which enhances the stress tolerance of plants. The destruction of vascular bundles may lead to the accumulation of anthocyanin; however, the response mechanism on this phenomenon in foxtail millet is not well understood. In this study, a foxtail millet variety Hong Miao Qi Tou Hong (HMQTH) which displayed increasing anthocyanin accumulation after leaf breakage was investigated. Through transcriptome analysis the gene expression pattern induced by leaf breakage in HMQTH was identified. Differentially expressed genes (DEGs) were mainly enriched in processes such as stimulus response, antioxidant function and flavonoid biosynthesis. Both the results of RNA-seq and qRT-PCR showed a total of 18 differential genes related to stress response and anthocyanin biosynthesis pathways were identified, including 7 genes involved in flavonoid and anthocyanin synthesis, 6 genes which were related to stress response and 5 genes regulating phytohormone synthesis and ABA signaling. This study uncovered the relationship between plant response to wounding and anthocyanin accumulation in foxtail millet, and provided genetic resources for the molecular breeding of crops with high anthocyanin content.