Feng Haiyang, Xu Liang, Wang Yan, Tang Mingjia, Zhu Xianwen, Zhang Wei, Sun Xiaochuan, Nie Shanshan, Muleke Everlyne M'mbone, Liu Liwang
National Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108, USA.
Mol Genet Genomics. 2017 Oct;292(5):1151-1163. doi: 10.1007/s00438-017-1338-9. Epub 2017 Jun 30.
Radish is an important root vegetable crop with high nutritional, economic, and medicinal value. Lignin is an important secondary metabolite possessing a great effect on plant growth and product quality. To date, lignin biosynthesis-related genes have been identified in some important plant species. However, little information on characterization of critical genes involved in plant lignin biosynthesis is available in radish. In this study, a total of 71,148 transcripts sequences were obtained from radish root, of which 66 assembled unigenes and ten candidate genes were identified to be involved in lignin monolignol biosynthesis. Full-length cDNA sequences of seven randomly selected genes were isolated and sequenced from radish root, and the assembled unigenes covered more than 80% of their corresponding cDNA sequences. Moreover, the lignin content gradually accumulated in leaf during the developmental stages, and it increased from pre-cortex to cortex splitting stage, followed by a decrease at thickening stage and then increased at mature stage in root. RT-qPCR analysis revealed that all these genes except RsF5H exhibited relatively low expression level in root at thickening stage. The expression profiles of Rs4CL5, RsCCoAOMT1, and RsCOMT genes were consistent with the changes of root lignin content, implying that these candidate genes may play important roles in lignin formation in radish root. These findings would provide valuable information for identification of lignin biosynthesis-related genes and facilitate dissection of molecular mechanism underlying lignin biosynthesis in radish and other root vegetable crops.
萝卜是一种重要的根菜类作物，具有很高的营养、经济和药用价值。木质素是一种重要的次生代谢产物，对植物生长和产品品质有很大影响。迄今为止，已在一些重要植物物种中鉴定出与木质素生物合成相关的基因。然而，关于萝卜中参与植物木质素生物合成的关键基因的特征信息却很少。在本研究中，从萝卜根中获得了总共71148条转录本序列，其中66个组装单基因和10个候选基因被鉴定为参与木质素单体生物合成。从萝卜根中分离并测序了随机选择的7个基因的全长cDNA序列，组装的单基因覆盖了其相应cDNA序列的80%以上。此外，木质素含量在叶片发育阶段逐渐积累，在根中从皮层前期到皮层分裂期增加，随后在加粗期下降，然后在成熟期增加。RT-qPCR分析表明，除RsF5H外，所有这些基因在加粗期根中的表达水平相对较低。Rs4CL5、RsCCoAOMT1和RsCOMT基因的表达谱与根木质素含量的变化一致，这意味着这些候选基因可能在萝卜根木质素形成中起重要作用。这些发现将为鉴定木质素生物合成相关基因提供有价值的信息，并有助于剖析萝卜和其他根菜类作物中木质素生物合成的分子机制。
