Genome-wide analysis of the KANADI gene family and its expression patterns under different nitrogen treatments in Populus trichocarpa

Abstract Background KANADI(KAN) was a plant-specific gene that controlled the polarity development of lateral organs. It mainly acted on the abaxial characteristics of plants to make the lateral organs asymmetrical. However, it had not been identified in woody plants. Methods and Results In this study, the members of the KAN gene family in Populus trichocarpawere identified and analyzed using the bioinformatics method. The results showed that a total of 8 KAN family members were screened out, and each member contained the unique GARP domain and conserved region of the family proteins. Phylogenetic analysis and their gene structures revealed that all KANgenes from P. trichocarpa, Arabidopsis thaliana, and Nicotiana benthamiana could be divided into four subgroups, while the eight genes in P.trichocarpa were classified into three subgroups, respectively. The analysis of tissue-specific expression indicated that PtKAN1 was highly expressed in young leaves, PtKAN6 was highly expressed in young leaves and mature leaves, PtKAN2, PtKAN5, and PtKAN7 were highly expressed in nodes and internodes, PtKAN8was highly expressed in roots, and PtKAN3 and PtKAN4 showed low expression levels in all tissues. Among them, PtKAN2and PtKAN6, and PtKAN4 and PtKAN5 might have functional redundancy. Under high nitrogen concentrations, PtKAN2 and PtKAN8were highly expressed in mature stems and leaves, respectively, while PtKAN4, PtKAN5, and PtKAN7 were highly expressed in roots. Conclusions This study laid a theoretical foundation for further study of the KANgene-mediated nitrogen effect on root development.