Abstract：
The GRF gene family plays an important role in plant growth and development as regulators involved in plant hormone signaling and metabolism. However, the Juglandaceae GRF gene family remains to be studied. Here, we identified 15, 15, 19, and 20 GRF genes in J. regia, C. illinoinensis, J. sigillata, and J. mandshurica, respectively. The phylogeny shows that the Juglandaceae family GRF is divided into two subfamilies, the ε-group and the non-ε-group, and that selection pressure analysis did not detect amino acid loci subject to positive selection pressure. In addition, we found that the duplications of the Juglandaceae family GRF genes were all segmental duplication events, and a total of 79 orthologous gene pairs and one paralogous homologous gene pair were identified in four Juglandaceae families. The Ka/KS ratios between these homologous gene pairs were further analyzed, and the Ka/KS values were all less than 1, indicating that purifying selection plays an important role in the evolution of the Juglandaceae family GRF genes. The codon bias of genes in the GRF family of Juglandaceae species is weak, and is affected by both natural selection pressure and base mutation, and translation selection plays a dominant role in the mutation pressure in codon usage. Finally, expression analysis showed that GRF genes play important roles in pecan embryo development and walnut male and female flower bud development, but with different expression patterns. In conclusion, this study will serve as a rich genetic resource for exploring the molecular mechanisms of flower bud differentiation and embryo development in Juglandaceae. In addition, this is the first study to report the GRF gene family in the Juglandaceae family; therefore, our study will provide guidance for future comparative and functional genomic studies of the GRF gene family in the Juglandaceae specie.
摘要：
GRF基因家族作为调节因子参与植物激素信号传导和代谢,在植物生长发育中起着重要作用。然而,核桃科GRF基因家族还有待研究。这里,我们确定了15、15、19和20个GRF基因。C.Illinoinensis，J.西吉拉塔，和J.Mandshurica,分别。系统发育表明，核桃科GRF家族分为两个亚科，ε-基团和非ε-基团，选择压力分析未检测到接受正选择压力的氨基酸位点。此外,我们发现核桃科GRF基因的重复都是节段性重复事件，在四个核桃科中共鉴定出79个直系同源基因对和一个同源同源基因对。进一步分析了这些同源基因对之间的Ka/KS比率，且Ka/KS值均小于1,说明纯化选择在核桃科GRF基因的进化过程中起着重要作用。核桃科植物GRF家族基因的密码子偏倚性较弱，受到自然选择压力和碱基突变的影响，翻译选择在密码子使用的突变压力中起主导作用。最后,表达分析表明,GRF基因在山核桃胚发育和核桃雌雄花芽发育中起重要作用,但是表达模式不同。总之,本研究将为探索核桃科花芽分化和胚胎发育的分子机制提供丰富的遗传资源。此外,这是第一个报道核桃科GRF基因家族的研究；因此，我们的研究将为核桃科植物GRF基因家族的未来比较和功能基因组研究提供指导。
