Genome-Wide Analysis Elucidates the Roles of AhLBD Genes in Different Abiotic Stresses and Growth and Development Stages in the Peanut (Arachis hypogea L.)

The lateral organ boundaries domain (<i>LBD</i>) genes, as the plant-specific transcription factor family, play a crucial role in controlling plant architecture and stress tolerance. However, the functions of <i>AhLBD</i> genes in the peanut plant (<i>Arachis hypogea</i> L.) remain unclear. In this study, 73 <i>AhLBDs</i> were identified in the peanut plant and divided into three groups by phylogenetic tree analysis. Gene structure and conserved protein motif analysis supported the evolutionary conservation of <i>AhLBDs</i>. Tandem and segment duplications contributed to the expansion of <i>AhLBDs</i>. The evolutionary relationship analysis of <i>LBD</i> gene family between <i>A. hypogaea</i> and four other species indicated that the peanut plant had a close relationship with the soybean plant. <i>AhLBDs</i> played a very important role in response to growth and development as well as abiotic stress. Furthermore, gene expression profiling and real-time quantitative qRT-PCR analysis showed that <i>AhLBD16</i>, <i>AhLBD33</i>, <i>AhLBD67</i>, and <i>AhLBD72</i> were candidate genes for salt stress, while <i>AhLBD24</i>, <i>AhLBD33</i>, <i>AhLBD35</i>, <i>AhLBD52</i>, <i>AhLBD67</i>, and <i>AhLBD71</i> were candidate genes for drought stress. Our subcellular localization experiment revealed that <i>AhLBD24</i>, <i>AhLBD33</i>, <i>AhLBD67</i>, and <i>AhLBD71</i> were located in the nucleus. Heterologous overexpression of <i>AhLBD33</i> and <i>AhLBD67</i> in <i>Arabidopsis</i> significantly enhanced tolerance to salt stress. Our results provide a theoretical basis and candidate genes for studying the molecular mechanism for abiotic stress in the peanut plant.