Genome-Wide Analysis of Caffeoyl-CoA-O-methyltransferase (CCoAOMT) Family Genes and the Roles of <i>GhCCoAOMT7</i> in Lignin Synthesis in Cotton

Caffeoyl coenzyme A-O-methyltransferase (CCoAOMT) has a critical function in the lignin biosynthesis pathway. However, its functions in cotton are not clear. In this research, we observed 50 <i>CCoAOMT</i> genes from four cotton species, including two diploids (<i>Gossypium arboret...

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Main Authors: Lina Ma, Jin Wang, Kaikai Qiao, Yuewei Quan, Shuli Fan, Liqiang Wu
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/13/21/2969
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Summary:Caffeoyl coenzyme A-O-methyltransferase (CCoAOMT) has a critical function in the lignin biosynthesis pathway. However, its functions in cotton are not clear. In this research, we observed 50 <i>CCoAOMT</i> genes from four cotton species, including two diploids (<i>Gossypium arboretum</i>, 9, and <i>Gossypium raimondii, 8</i>) and two tetraploids (<i>Gossypium hirsutum</i>, 16, and <i>Gossypium barbadense, 17</i>), performed bioinformatic analysis, and focused on the involvement and functions of <i>GhCCoAOMT7</i> in lignin synthesis of <i>Gossypium hirsutum</i>. CCoAOMT proteins were divided into four subgroups based on the phylogenetic tree analysis. Motif analysis revealed that all CCoAOMT proteins possess conserved Methyltransf_3 domains, and conserved structural features were identified based on the genes’ exon-intron organization. A synteny analysis suggested that segmental duplications were the primary cause in the expansion of the <i>CCoAOMT</i> genes family. Transcriptomic data analysis of <i>GhCCoAOMTs</i> revealed that <i>GhCCoAOMT2</i>, <i>GhCCoAOMT7,</i> and <i>GhCCoAOMT14</i> were highly expressed in stems. Subcellular localization experiments of <i>GhCCoAOMT2</i>, <i>GhCCoAOMT7</i>, and <i>GhCCoAOMT14</i> showed that <i>GhCCoAOMT2</i>, <i>GhCCoAOMT7</i>, and <i>GhCCoAOMT14</i> were localized in the nucleus and plasma membrane. However, there are no <i>cis</i>-regulatory elements related to lignin synthesis in the <i>GhCCoAOMT7</i> gene promoter. <i>GhCCoAOMT7</i> expression was inhibited by virus-induced gene silencing technology to obtain gene silencing lines, the suppression of <i>GhCCoAOMT7</i> expression resulted in a 56% reduction in the lignin content in cotton stems, and the phloroglucinol staining area corresponding to the xylem was significantly decreased, indicating that <i>GhCCoAOMT7</i> positively regulates lignin synthesis. Our results provided fundamental information regarding <i>CCoAOMTs</i> and highlighted their potential functions in cotton lignin biosynthesis and lignification.
ISSN:2223-7747