biostudies-literatureUnknown13Zhang YMechanical strength is essential for the upright growth habit, which is one of the most important characteristics of terrestrial plants. Lignin, a phenylpropanoid-derived polymer mainly present in secondary cell walls plays critical role in providing mechanical support. Here, we report that the prostrate-stem cultivar of the legume forage <i>Medicago ruthenica</i> cultivar 'Mengnong No. 1' shows compromised mechanical strength compared with the erect-stem cultivar 'Zhilixing'. The erect-stem cultivar, 'Zhilixing' has significantly higher lignin content, leading to higher mechanical strength than the prostrate-stem cultivar. The low abundance of miRNA397a in the Zhiixing cultivar causes reduced cleavage of <i>MrLAC17</i> transcript, which results in enhanced expression level of <i>MrLAC17</i> compared to that in the prostrate-stem cultivar Mengnong No. 1. Complementation of the <i>Arabidopsis lac4 lac17</i> double mutants with <i>MrLAC17</i> restored the lignin content to wild-type levels, confirming that MrLAC17 perform an exchangeable role with <i>Arabidopsis</i> laccases. <i>LAC17-</i>mediated lignin polymerization is therefore increased in the 'Zhilixing', causing the erect stem phenotype. Our data reveal the importance of the miR397a in the lignin biosynthesis and suggest a strategy for molecular breeding targeting plant architecture in legume forage.Frontiers in plant science978515https://www.ebi.ac.uk/biostudies/studies/S-EPMC9434696biostudies-literatureThe MicroRNA397a-LACCASE17 module regulates lignin biosynthesis in <i>Medicago ruthenica</i> (L.).PMC9434696Shan XZhang YZhao QShi FfalseThe MicroRNA397a-LACCASE17 module regulates lignin biosynthesis in <i>Medicago ruthenica</i> (L.).Mechanical strength is essential for the upright growth habit, which is one of the most important characteristics of terrestrial plants. Lignin, a phenylpropanoid-derived polymer mainly present in secondary cell walls plays critical role in providing mechanical support. Here, we report that the prostrate-stem cultivar of the legume forage <i>Medicago ruthenica</i> cultivar 'Mengnong No. 1' shows compromised mechanical strength compared with the erect-stem cultivar 'Zhilixing'. The erect-stem cultivar, 'Zhilixing' has significantly higher lignin content, leading to higher mechanical strength than the prostrate-stem cultivar. The low abundance of miRNA397a in the Zhiixing cultivar causes reduced cleavage of <i>MrLAC17</i> transcript, which results in enhanced expression level of <i>MrLAC17</i> compared to that in the prostrate-stem cultivar Mengnong No. 1. Complementation of the <i>Arabidopsis lac4 lac17</i> double mutants with <i>MrLAC17</i> restored the lignin content to wild-type levels, confirming that MrLAC17 perform an exchangeable role with <i>Arabidopsis</i> laccases. <i>LAC17-</i>mediated lignin polymerization is therefore increased in the 'Zhilixing', causing the erect stem phenotype. Our data reveal the importance of the miR397a in the lignin biosynthesis and suggest a strategy for molecular breeding targeting plant architecture in legume forage.2022-01-01T00:00:00Z20222024-10-16T04:16:57.624Z2024-10-16T04:16:57.624ZS-EPMC94346963606177210.3389/fpls.2022.978515