Genome wide identification of GRAS gene family in bread wheat Triticum aestivum L

Abstract

newline Wheat (Triticum aestivum) is one of the most widely cultivated cereal crops, serving as a staple food for billions of people worldwide. It is a primary source of calories and essential nutrients, making it crucial for global food security. However, wheat production faces significant challenges, including abiotic stresses such as drought, salinity, and heat, which are exacerbated by climate change. These stresses disrupt growth and yield, compounded by biotic threats like pests and diseases. Addressing these challenges requires innovative strategies to enhance stress tolerance and maintain productivity in changing environmental conditions. GRAS transcription factors are a vital family of plant-specific regulatory proteins involved in various biological processes, including growth, development, and stress responses. Named after the key members GAI, RGA, and SCR, these transcription factors play critical roles in gibberellin signaling, root development, shoot meristem maintenance, and phytochrome signaling. Structurally, they feature a conserved C-terminal domain essential for protein-protein interactions and a variable N-terminal region that provides functional diversity. GRAS proteins regulate vital processes such as root architecture, symbiotic interactions, and abiotic stress responses like drought and salinity tolerance. Their ability to modulate plant growth, environmental adaptation, and nutrient acquisition makes them promising targets for developing resilient and high-yielding crop varieties. newlineIn the current study, we embarked on a systematic exploration of GRAS genes within Triticum aestivum L. and undertook a comprehensive analysis, including gene structure examination, chromosomal mapping, identification of conserved motifs, establishment of phylogenetic relationships, and analysis of expression patterns. Within the wheat genome, we identified 180 GRAS genes, subsequently categorized into 14 distinct subfamilies based on phylogenetic analysis. While analyzing the genetic makeup of TaGRAS genes, it was found that introns are absent from the bulk of wheat GRAS genes. The study demonstrated the important role duplication events like tandem and segmental play in the establishment of GRAS gene proliferation in the wheat genome. By examining collinearity events between wheat GRAS genes and orthologs from other plant species, the evolutionary trajectory of the GRAS genes was better understood. Analysis of the promoter region of TaGRAS genes repeatedly revealed cis-acting regions linked to stress and hormones. newlineTo comprehend the regulatory dynamics of abiotic stress and miRNAs, ten stress-responsive miRNAs were studied in two different wheat genotypes: drought-susceptible WL 711 and drought-resistant C-306. Among these miRNAs, three showed upregulation, while seven showed downregulation under stress conditions. Intriguingly, GRAS genes, as targets of these miRNAs, showcased an upregulation trend during drought stress. Notably, miR159 targeting TaGRAS178 and miR408- TaGRAS84, exhibited enhanced expression in response to drought stress. Remarkably, miR408 is a conserved microRNA that is well-known for being essential in controlling many facets of plant growth, development, and responses to environmental stresses, underscoring its profound importance. This study uncovered a regulatory network wherein a total of fourteen miRNAs were found to interact with 55 GRAS targets spanning multiple subfamilies within wheat, collectively exerting a discernible influence on plant growth and developmental processes. Furthermore, validation of considerable elevation of TaGRAS genes in response to salt, heat, and drought conditions using a combination of RNA-seq data and qRT-PCR analysis, highlighting their critical function in a variety of stress conditions. In conclusion, the analysis improves the knowledge of the arrangement of GRAS genes in the entire genome. Additionally, TaGRAS27 was shown to be a promising gene for additional functional investigation and to have the ability to improve wheat and resistance to abiotic stress using molecular breeding techniques. newlineviii. Keywords: Transcription factor, GRAS, abiotic stress, gene expression, wheat newline newline newline newline newline newline