Galactinol synthase (GolS) is a key enzyme in raffinose family oligosaccharide (RFO) biosynthesis. The finding that GolS accumulates in plants exposed to abiotic stresses indicates RFOs function in environmental adaptation. However, the evolutionary relationships and biological functions of GolS family in rapeseed (Brassica napus) and tobacco (Nicotiana tabacum) remain unclear. In this study, we identified 20 BnGolS and 9 NtGolS genes. Subcellular localization predictions showed that most of the proteins are localized to the cytoplasm. Phylogenetic analysis identified a lost event of an ancient GolS copy in the Solanaceae and an ancient duplication event leading to evolution of GolS4/7 in the Brassicaceae. The three-dimensional structures of two GolS proteins were conserved, with an important DxD motif for binding to UDP-galactose (uridine diphosphate-galactose) and inositol. Expression profile analysis indicated that BnGolS and NtGolS genes were expressed in most tissues and highly expressed in one or two specific tissues. Hormone treatments strongly induced the expression of most BnGolS genes and homologous genes in the same subfamilies exhibited divergent-induced expression. Our study provides a comprehensive evolutionary analysis of GolS genes among the Brassicaceae and Solanaceae as well as an insight into the biological function of GolS genes in hormone response in plants.

Hypersensitive-induced response protein (HIR) is a class of plant immune proteins that play pivotal roles in Sclerotinia sclerotiorum (Lib.) de Bary resistance. However, there has been no systematic investigation and identification of HIR genes in rapeseed (Brassica napus L.). Hence, we identified 50 BnHIR genes and classified them into four groups. Subcellular localization prediction suggested that HIR proteins are mainly localized in the mitochondria. Cis-acting elements involved in light and diverse abiotic stress were found in the promoter regions of BnHIR. The majority of BnHIR genes in Groups 1/3/4 were expressed in most examined tissues, especially in leaves and siliques pericarp, while the BnHIR genes in Group 2 were not or had low expression in all detected tissues. In the case of S. sclerotiorum inoculation, HIR genes in Groups 1/3/4 were strongly induced, especially homologous genes in Group 1, which exhibited different expression patterns. Moreover, overexpression of BnHIR2.7 in Arabidopsis thaliana illustrated its prominent resistance to S. sclerotiorum. Our study provides insight into the evolutionary relationships of the HIR family genes in B. napus and lays the foundation for their resistance to S. sclerotiorum in B. napus.