Abstract
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 the GRAS gene family to be identified and characterized in many species. However, thorough in-depth identification or systematic analysis of GRAS family genes in foxtail millet has not been conducted.ResultsIn this study, 57 GRAS genes of foxtail millet (SiGRASs) were identified and renamed according to the chromosomal distribution of the SiGRAS genes. Based on the number of conserved domains and gene structure, the SiGRAS genes were divided into 13 subfamilies via phylogenetic tree analysis. The GRAS genes were unevenly distributed on nine chromosomes, and members of the same subfamily had similar gene structures and motif compositions. Genetic structure analysis showed that most SiGRAS genes lacked introns. Some SiGRAS genes were derived from gene duplication events, and segmental duplications may have contributed more to GRAS gene family expansion than tandem duplications. Quantitative polymerase chain reaction showed significant differences in the expression of SiGRAS genes in different tissues and stages of fruits development, which indicated the complexity of the physiological functions of SiGRAS. 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, SiGRAS13 and SiGRAS25 may 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 of SiGRAS. Our results may contribute to improving the genetic breeding of foxtail millet.
Highlights
GRAS transcription factors perform indispensable functions in various biological processes, such as plant growth, fruit development, and biotic and abiotic stress responses
Differentiation at the N-terminal further leads to the diversification of GRAS proteins, for example, the DELLA proteins are characterized by the DELLA domain at the N-terminal [6]
In the predicted subcellular localization results, 26 Setaria italica GRAS (SiGRAS) proteins were located in the nucleus, 16 were located in the cytoplasm, 13 were located in the chloroplasts, 1 was located in the chloroplasts, and 1 was located in the mitochondria (Table S1)
Summary
GRAS transcription factors perform indispensable functions in various biological processes, such as plant growth, fruit development, and biotic and abiotic stress responses. The N-terminal of GRAS proteins constituted an intrinsically disordered region (IDR) peculiar to plants This domain is highly variable and can switch. The C-terminal sequence of GRAS transcription factors is relatively conserved, has specific transcription regulatory domains that bind to DNA or other proteins, and can recognize a variety of different target receptors. The C-terminal of GRAS protein contains five highly conserved domains:leucineheptad repeat I (LHR I), Val-His-Ile-Ile-Asp (VHIID), leucine-heptad repeat II (LHR II), Pro-Phe-Tyr-Arg-Glu (PFYRE), and Ser-Ala-Trp (SAW) [7]. The SAW motif comprises three consecutive parts near the C terminal, namely WX7G (X7 represents any seven amino acids), L-W, and SAW These conserved elements play an important role in maintaining the integrity of the GRAS domain [13, 14]
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