Genome-Wide Identification, Evolution and Expression Analysis of GRAS Transcription Factor Gene Family Under Viral Stress in Nicotiana benthamiana

The <i>GRAS</i> gene family not only performs a variety of regulatory functions in plant growth and development but also plays a key role in the defense mechanisms of plants in response to environmental stresses. Although <i>GRASs</i> have been identified in many species, research on them in <i>Nicotiana benthamiana</i> remains relatively limited until now. In this study, we comprehensively analyzed the <i>GRAS</i> gene family in <i>N. benthamiana</i> plants. Phylogenetic analysis displayed that all identified <i>NbGRASs</i> were classified into eight different subfamilies. Gene duplication analysis revealed that segmental duplication was the main driving force for the expansion of the <i>NbGRAS</i> gene family, with a total of 40 segmental duplication pairs identified. <i>NbGRASs</i> were unevenly distributed across the 19 chromosomes. Additionally, both gene families exhibited a relatively weak codon usage bias, a pattern shaped by mutational and selective pressures. Expression analysis showed that <i>NbGRASs</i> had tissue-specific expression patterns, with relatively high expression levels being observed in leaves and roots. The expression of <i>NbGRASs</i> was significantly changed under <i>tomato yellow leaf curl virus</i> or <i>bamboo mosaic virus</i> infection, suggesting that these <i>NbGRASs</i> can be involved in the plant's antiviral response. These findings provide new perspectives for in-depth understanding of the evolution and functions of the <i>GRAS</i> gene family in <i>N. benthamiana</i>.