AUTHOR=Borah Priyanka , Ni Fei , Ying Weiyang , Zhuang Hebi , Chong Sun-Li , Hu Xian-Ge , Yang Jun , Lin Er-pei , Huang Huahong 

TITLE=Genome-wide identification and characterization of OVATE family proteins in Betula luminifera reveals involvement of BlOFP3 and BlOFP5 genes in leaf development

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.950936

DOI=10.3389/fpls.2022.950936

ISSN=1664-462X

ABSTRACT=<p>Ovate family proteins (OFP) are plant-specific transcription factors involved in regulating morphologies of the lateral organs, plant growth and development. However, the functional roles of <italic>OFP</italic> genes in <italic>Betula luminifera</italic>, an important timber tree species, are not well studied. In this study, we identified 20 <italic>BlOFP</italic> genes and analyzed their phylogenetic relationship, gene structure, conserved motifs, and <italic>cis</italic>-elements. Further, expression analysis indicates that <italic>BlOFP</italic> genes were up-regulated in leaves on the one-year-old branch compared to leaves on the current-year branch and bract, except <italic>BlOFP7</italic>, <italic>BlOFP11</italic>, <italic>BlOFP14</italic> and <italic>BlOFP12</italic>. The overexpression of <italic>BlOFP3</italic> and <italic>BlOFP5</italic> in <italic>Arabidopsis thaliana</italic> not only resulted in a slower growth rate but also produced sawtooth shape, flatter and darker green rosette leaves. Further investigation showed that the leaf thickness of the transgenic plants was more than double that of the wild type, which was caused by the increasement in the number and size of palisade tissue cells. Furthermore, the expression analysis also indicated that the expressions of several genes related to leaf development were significantly changed in the transgene plants. These results suggested the significant roles of <italic>BlOFP3</italic> and <italic>BlOFP5</italic> in leaf development. Moreover, protein-protein interaction studies showed that BlOFP3 interacts with BlKNAT5, and BlOFP5 interacts with BlKNAT5, BlBLH6 and BlBLH7. In conclusion, our study demonstrates that BlOFP3 and BlOFP5 were involved in leaf shape and thickness regulation by forming a complex with BlKNAT5, BlBLH6 and BlBLH7. In addition, our study serves as a guide for future functional genomic studies of <italic>OFP</italic> genes of the <italic>B. luminifera</italic>.</p>