Abstract
The GRAS 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 GRASs have been identified in many species, research on them in Nicotiana benthamiana remains relatively limited until now. In this study, we comprehensively analyzed the GRAS gene family in N. benthamiana plants. Phylogenetic analysis displayed that all identified NbGRASs were classified into eight different subfamilies. Gene duplication analysis revealed that segmental duplication was the main driving force for the expansion of the NbGRAS gene family, with a total of 40 segmental duplication pairs identified. NbGRASs 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 NbGRASs had tissue-specific expression patterns, with relatively high expression levels being observed in leaves and roots. The expression of NbGRASs was significantly changed under tomato yellow leaf curl virus or bamboo mosaic virus infection, suggesting that these NbGRASs 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 GRAS gene family in N. benthamiana.