The Identification and Characterization of the Gene Family in Oliv. Heteromorphic Leaves Provide a Theoretical Basis for the Functional Study of .

Oliv. typically has four kinds of heteromorphic leaves: linear (Li), lanceolate (La), ovate (Ov) and broad ovate (Bo). Heteromorphic leaves help adapt to extreme desert environments and further contribute to protection against land desertification in Northwest China. In the authors' previous research, growth-regulating factors (GRFs) were speculated to be related to the development of heteromorphic leaves via multi-omics integrated analysis. However, the genomic features and biological role of the gene family in heteromorphic leaves are still unclear. In this study, 19 genes were genome-widely identified and characterized in , and their physicochemical properties, gene structure and phylogenetic evolution were analyzed. An analysis of the research showed that were unevenly distributed on 11 chromosomes and that PeGRF proteins contained conserved motif 1 (WRC) and motif 2 (QLQ). Moreover, 19, 15, 19 and 22 were identified in Marshall, Schrenk, C. Wang et C. Y. Yang and W. C. Cheng, respectively. A collinearity analysis showed that the family evolved slowly within Populus species. A phylogenetic tree of the GRF family was also constructed, and GRFs were divided into four subfamilies. A large number of cis-acting elements were related to plant growth and development, plant hormone response and stress response on the promoter of . The expression pattern of showed significant up-regulation in broad leaves (Ov and Bo) compared with narrow leaves (Li and La). In combination with the predicted gene regulatory network, () may have an important contribution to the leaf shape development of The heterologous expression of in wild-type plants (Col-0) of (L.) Heynh was also studied, showing a significant increase in the leaf area of overexpressing plants compared with the wild type. Nineteen gene members were identified and characterized in , and a comparison of the genomic analysis of Populus GRF members revealed their evolutionary features. The further overexpression of in revealed its biological role in the heteromorphic leaves of This study not only provides new insights into the evolution and function of PeGRFs in heteromorphic leaves but also helps in an understanding of the adaptive evolution of in drought desert environments.