Genome-wide investigation of the GRAS transcription factor family in foxtail millet (Setaria italica L.)

BackgroundGRAS transcription factors perform indispensable functions in various biological processes, such as plant growth, fruit development, and biotic and abiotic stress responses. The development of whole-genome sequencing has allowed theGRASgene family to be identified and characterized in many species. However, thorough in-depth identification or systematic analysis ofGRASfamily genes in foxtail millet has not been conducted.ResultsIn this study, 57GRASgenes of foxtail millet (SiGRASs) were identified and renamed according to the chromosomal distribution of theSiGRASgenes. Based on the number of conserved domains and gene structure, theSiGRASgenes were divided into 13 subfamilies via phylogenetic tree analysis. TheGRASgenes were unevenly distributed on nine chromosomes, and members of the same subfamily had similar gene structures and motif compositions. Genetic structure analysis showed that mostSiGRASgenes lacked introns. SomeSiGRASgenes were derived from gene duplication events, and segmental duplications may have contributed more toGRASgene family expansion than tandem duplications. Quantitative polymerase chain reaction showed significant differences in the expression ofSiGRASgenes in different tissues and stages of fruits development, which indicated the complexity of the physiological functions ofSiGRAS. In addition, exogenous paclobutrazol treatment significantly altered the transcription levels of DELLA subfamily members, downregulated the gibberellin content, and decreased the plant height of foxtail millet, while it increased the fruit weight. In addition,SiGRAS13andSiGRAS25may have the potential for genetic improvement and functional gene research in foxtail millet.ConclusionsCollectively, this study will be helpful for further analysing the biological function ofSiGRAS. Our results may contribute to improving the genetic breeding of foxtail millet.