Genome-Wide Identification, Bioinformatic Characterization, and Expression Profiling of Starch Synthase (SS) Genes in Foxtail Millet under Drought Condition

Millet, a vital and nutritionally dense cereal extensively cultivated in Sub-Saharan Africa, plays a key role in ensuring food security. This study investigates the starch synthase (SS) gene family, which is crucial for starch biosynthesis and influences various plant functions and stress responses. While the specific roles of SS genes in millet under drought conditions are not fully elucidated, this research provides a thorough analysis of the SS gene family in millet. A total of twelve millet SS genes (SiSSs) were identified and classified into four subfamilies (I–IV) through gene structure and phylogenetic analysis. The SiSS genes were unevenly distributed across millet chromosomes, with cis-acting elements associated with plant growth and stress defense being identified. Quantitative PCR (qPCR) revealed dynamic and varied expression patterns of SiSSs in different tissues under drought stress. Millet plants subjected to drought conditions showed higher tissue starch content and increased starch synthase activity compared to controls. Importantly, the expression levels of the twelve SiSSs were positively correlated with both starch content and synthase activity, suggesting their significant role in drought tolerance. This study enhances our understanding of the millet SS gene family and highlights the potential of these genes in breeding programs aimed at developing drought-resistant millet varieties. Further research is recommended to validate these findings and delve deeper into the mechanisms underlying drought tolerance.