Cao Shumin, Huang Cheng, Luo Laifu, Zheng Shuai, Zhong Yu, Sun Jiayan, Gui Jinshan, Li Laigeng
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
University of the Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2020 Nov 17;11:589729. doi: 10.3389/fpls.2020.589729. eCollection 2020.
Lignin is a main component of the secondary cell wall in vessels and fibers of xylem tissue. However, the significance of lignin in cell physiology during plant growth is unclear. In this study, we generated lignin-modified via cell-specific downregulation of the 4-coumarate-CoA ligase gene (). The transgenic plants with selective lignin modification in vessel elements or fiber cells allowed us to investigate how lignin affects the physiology of vessel or fiber cells in relation to plant growth. Results showed that vessel-specific suppression of lignin biosynthesis resulted in deformed vessels and normal fibers, while fiber-specific suppression of lignin biosynthesis led to less-lignified fibers and normal vessels. Further analyses revealed that the efficiency of long distance water transport was severely affected in transgenics with vessel-specific lignin modification, while minimal effect was detected in transgenics with fiber-specific lignin modification. Vessel-specific lignin reduction led to high susceptibility to drought stress and poor growth in field, likely due to vessel defects in long distance transport of water. The distinct physiological significance of lignin in different cell types provides insights into the selective modification of lignin for improvement of lignocellulosic biomass utilization.
木质素是木质部组织中导管和纤维次生细胞壁的主要成分。然而，木质素在植物生长过程中细胞生理方面的重要性尚不清楚。在本研究中，我们通过细胞特异性下调4-香豆酸-CoA连接酶基因（）来生成木质素修饰。在导管分子或纤维细胞中具有选择性木质素修饰的转基因植物使我们能够研究木质素如何影响与植物生长相关的导管或纤维细胞的生理。结果表明，导管特异性抑制木质素生物合成导致导管变形而纤维正常，而纤维特异性抑制木质素生物合成导致木质化程度较低的纤维和正常导管。进一步分析表明，在具有导管特异性木质素修饰的转基因植物中，长距离水分运输效率受到严重影响，而在具有纤维特异性木质素修饰的转基因植物中检测到的影响最小。导管特异性木质素减少导致对干旱胁迫高度敏感且田间生长不良，这可能是由于水分长距离运输中的导管缺陷所致。木质素在不同细胞类型中的独特生理意义为木质素的选择性修饰以改善木质纤维素生物质利用提供了见解。
