Zhang Yutong, Shan Xiaotong, Zhao Qiao, Shi Fengling
Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization of the Ministry of Agriculture and Key Laboratory of Grassland Resources of the Ministry of Education, College of Grassland Resources and Environment, Inner Mongolia Agricultural University, Hohhot, China.
Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
Front Plant Sci. 2022 Aug 18;13:978515. doi: 10.3389/fpls.2022.978515. eCollection 2022.
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 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 transcript, which results in enhanced expression level of compared to that in the prostrate-stem cultivar Mengnong No. 1. Complementation of the double mutants with restored the lignin content to wild-type levels, confirming that MrLAC17 perform an exchangeable role with laccases. 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.
机械强度对于直立生长习性至关重要，而直立生长习性是陆生植物最重要的特征之一。木质素是一种主要存在于次生细胞壁中的苯丙烷衍生聚合物，在提供机械支撑方面发挥着关键作用。在此，我们报道豆科牧草品种‘蒙农1号’的匍匐茎品种与直立茎品种‘直立型’相比，机械强度受损。直立茎品种‘直立型’的木质素含量显著更高，导致其机械强度高于匍匐茎品种。直立型品种中miRNA397a丰度较低，导致转录本切割减少，与匍匐茎品种蒙农1号相比，导致其表达水平升高。用恢复了木质素含量至野生型水平，证实MrLAC17与漆酶发挥可互换作用。因此，在‘直立型’中，介导的木质素聚合增加，导致直立茎表型。我们的数据揭示了miR397a在木质素生物合成中的重要性，并提出了一种针对豆科牧草植株结构进行分子育种的策略。
