Insights into panicle trait variation and DUF-640 gene conservation in Indonesian foxtail millets (Setaria italica)

Foxtail millet (Setaria italica) is a resilient yet underutilised C4 cereal valued for its adaptability to abiotic stress and high nutritional content. While panicle traits have been linked to yield in many cereals, the spatial arrangement of foxtail millet panicles remained unexplored, especially among locally adapted genotypes. This study aimed to characterise spatial panicle architecture traits and to analyse the DUF-640, a gene controlling primary branch number, among Indonesian foxtail millet genotypes. Results revealed substantial variation in panicle architecture, including primary branch number, grain number, and grain density in eight Indonesian foxtail millet genotypes, suggesting potentially greater diversity across broader germplasm. In contrast to the substantial panicle trait variations, phylogenetic and structural analyses showed that DUF-640 genes were highly conserved across Setaria species. Although previously associated with primary branch development, the coding sequence of DUF-640 was not associated with branching variation in this study. However, its high sequence conservation across Setaria species suggests a vital and possibly conserved regulatory function. This study enhances the understanding of the morphological and genetic diversity of foxtail millet, particularly among Indonesian foxtail millet genotypes. Future research should focus on the functional characterisation of DUF-640 and the identification of regulatory sequences governing its gene expression.