NAC and MYB Families and Lignin Biosynthesis-Related Members Identification and Expression Analysis in <i>Melilotus Albus</i>

• Main Authors: Lijun Chen, Fan Wu, Jiyu Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Plants
• Subjects: <i>Melilotus albus</i>; NAC and MYB genes; expression analysis; promoter region; lignin biosynthesis
• Online Access: https://www.mdpi.com/2223-7747/10/2/303

<i>Melilotus albus</i> is an annual or biennial legume species that adapts to extreme environments via its high stress tolerance. NAC and MYB transcription factors (TFs) are involved in the regulation of lignin biosynthesis, which has not been studied in <i>M. albus</i>. A total of 101 <i>MaNAC</i> and 299 <i>MaMYB</i> members were identified based on <i>M. albus</i> genome. Chromosome distribution and synteny analysis indicated that some genes underwent tandem duplication. Ka/Ks analysis suggested that <i>MaNAC</i>s and <i>MaMYB</i>s underwent strong purifying selection. Stress-, hormone- and development-related cis-elements and MYB-binding sites were identified in the promoter regions of <i>MaNACs</i> and <i>MaMYBs</i>. Five <i>MaNAC</i>s, two <i>MaMYB</i>s and ten lignin biosynthesis genes were identified as presenting coexpression relationships according to weighted gene coexpression network analysis (WGCNA). Eleven and thirteen candidate <i>MaNAC</i> and <i>MaMYB</i> genes related to lignin biosynthesis were identified, respectively, and a network comprising these genes was constructed which further confirmed the <i>MaNAC</i> and <i>MaMYB</i> relationship. These candidate genes had conserved gene structures and motifs and were highly expressed in the stems and roots, and qRT-PCR further verified the expression patterns. Overall, our results provide a reference for determining the precise role of <i>NAC</i> and <i>MYB</i> genes in <i>M. albus</i> and may facilitate efforts to breed low-lignin-content forage cultivars in the future.