摘要
木质素是维管植物次生细胞壁的重要组分之一,具有重要的生物学功能。木质素分子与细胞壁中的纤维素、半纤维素等多糖分子相互交联,增加了植物细胞和组织的机械强度,其疏水性使植物细胞不易透水,利于水分及营养物质在植物体内的长距离运输。木质素与纤维素共同形成的天然物理屏障能有效阻止各种病原菌的入侵,增强了植物对各种生物及非生物胁迫的防御能力。然而木质素的存在也给人类的生产实践带来诸多负面影响,如造纸业中,由于必须使用大量化学药品去除木质素,加大了造纸成本,严重污染了环境;饲草中的高木质素含量则影响牲畜的消化吸收,降低了饲草的营养价值;过高的木质素含量也影响了人类对生物质能源的发酵利用。因此,利用基因工程改造植物木质素的可降解性意义重大。在高等植物中,木质素通过苯丙烷途径和木质素特异途径合成。在拟南芥中,NAC、MYB以及WRKY类转录因子都参与了对木质素生物合成的调控。在拟南芥中,MYB26可激活NST1/NST2的转录;WRKY12可与NST2的启动子区结合并对其表达进行负调控;SND1(NST3)和NST1主要在纤维次生壁的形成中发挥作用,两者功能有冗余;NST1和NST2在调控花药壁的次生壁的增厚中功能有冗余;VND6和VND7则主要在木质部导管的分化中起重要作用,这些NAC类转录因子通过与下游的MYB类转录因子如MYB83、MYB46及(或)MYB58、MYB63、MYB85和MYB103的结合对木质素合成基因的表达进行正调控,而MYB75对木质素生物合成进行负调控。多数MYB转录因子通过与下游木质素生物合成途径基因启动子区的AC元件(I、II和III)结合从而对其表达进行调控。研究表明,b HLH类转录因子也参与了对木质素生物合成的调控。文章综述了各类转录因子对木质素生物合成调控的最近进展,绘制了拟南芥中木质素生物合成的主要调控网络,同时也总结了其他物种(如水稻、小麦、玉米、桉树、松树和杨树等)中已发现的对木质素生物合成进行调控的转录因子。随着高通量测序技术的发展,研究者有望在更多的物种中发现参与木质素生物合成调控的关键转录因子,这些研究将对通过基因工程改造木质素的组成具有重要的借鉴意义。
Lignin is an important component of secondary cell wall in vascular plants and has important biological functions. Lignin, cellulose and hemicellulose are crosslinked in the cell wall and provide mechanical support for the plant cells and tissues. The hydrophobic property of lignin makes it impermeable to water, which facilitates the long-distance transport of water and nutrients in plant. Lignin and cellulose are natural physical barriers to various pathogens, which improve the defensive ability against biotic and abiotic stresses. While lignin also has some negative effects on the productive practice, e.g.,＆amp;nbsp;in pulp and paper industry, many chemicals must be used to remove lignin, which increases the cost of pulping and pollution to the environment. High lignin content in the forage decreases the digestibility of livestocks and affect the nutritive value of forages. Higher lignin content also has a negative effect on the fermentation efficiency of biomass energy. Therefore, it is of great significance to improve the lignin degradability by genetic engineering. In higher plants, lignin can be synthesized by phenylpropanoid pathway and specific lignin biosynthesis pathway. Previous research has shown that NAC, MYB and WRKY transcription factors involved in the regulation of lignin biosynthesis pathway. In Arabidopsis, MYB26 can activate the transcription of NST1/NST2; WRKY12 can bind to the promoter region of NST2 and regulate its expression negatively. SND1 （NST3） and NST1 function redundantly in the regulation of secondary wall synthesis in fibers; NST1 and NST2 are redundant in regulating secondary wall thickening in anther walls; VND6 and VND7 mainly involved in xylem vessel differentiation. All these NAC transcription factors can bind to the downstream MYB transcription factors such as MYB83, MYB46 as well as （or） MYB58, MYB63, MYB85 and MYB103 to regulate lignin biosynthesis positively, whereas MYB75 regulates the lignin biosynthesis negatively. Most of the MYBs in this network can bind to the AC elements （I, II and III） in the promoters of the lingin biosynthesis pathway genes and therefore regulate their expression. Some studies also suggested the involvement of bHLH transcription factors in the regulation of lignin biosynthesis pathway. In this paper, advances in research of the regulation of transcription factors on lignin biosynthesis were reviewed, the major regulatory network of lignin biosynthesis in Arabidopsis was produced, some transcription factors related to lignin biosynthesis in other species （e.g. rice, wheat, maize, eucalyptus, pine and populus） were also summarized. With the development of high-throughput sequencing technology, key regulatory transcription factors will be discovered in more species, which will have an important reference to the lignin modification by genetic engineering. Lignin is an important component of secondary cell wall in vascular plants and has important biological functions. Lignin, cellulose and hemicellulose are crosslinked in the cell wall and provide mechanical support for the plant cells and tissues. The hydrophobic property of lignin makes it impermeable to water, which facilitates the long-distance transport of water and nutrients in plant. Lignin and cellulose are natural physical barriers to various pathogens, which improve the defensive ability against biotic and abiotic stresses. While lignin also has some negative effects on the productive practice, e.g.,＆amp;nbsp;in pulp and paper industry, many chemicals must be used to remove lignin, which increases the cost of pulping and pollution to the environment. High lignin content in the forage decreases the digestibility of livestocks and affect the nutritive value of forages. Higher lignin content also has a negative effect on the fermentation efficiency of biomass energy. Therefore, it is of great significance to improve the lignin degradability by genetic engineering. In higher plants, lignin can be synthesized by phenylpropanoid pathway and specific lignin biosynthesis pathway. Previous research has shown that NAC, MYB and WRKY transcription factors involved in the regulation of lignin biosynthesis pathway. In Arabidopsis, MYB26 can activate the transcription of NST1/NST2; WRKY12 can bind to the promoter region of NST2 and regulate its expression negatively. SND1 （NST3） and NST1 function redundantly in the regulation of secondary wall synthesis in fibers; NST1 and NST2 are redundant in regulating secondary wall thickening in anther walls; VND6 and VND7 mainly involved in xylem vessel differentiation. All these NAC transcription factors can bind to the downstream MYB transcription factors such as MYB83, MYB46 as well as （or） MYB58, MYB63, MYB85 and MYB103 to regulate lignin biosynthesis positively, whereas MYB75 regulates the lignin biosynthesis negatively. Most of the MYBs in this network can bind to the AC elements （I, II and III） in the promoters of the lingin biosynthesis pathway genes and therefore regulate their expression. Some studies also suggested the involvement of bHLH transcription factors in the regulation of lignin biosynthesis pathway. In this paper, advances in research of the regulation of transcription factors on lignin biosynthesis were reviewed, the major regulatory network of lignin biosynthesis in Arabidopsis was produced, some transcription factors related to lignin biosynthesis in other species （e.g. rice, wheat, maize, eucalyptus, pine and populus） were also summarized. With the development of high-throughput sequencing technology, key regulatory transcription factors will be discovered in more species, which will have an important reference to the lignin modification by genetic engineering.
出处
《中国农业科学》
CAS
CSCD
北大核心
2015年第7期1277-1287,共11页
Scientia Agricultura Sinica
基金
国家自然科学基金(31101129)
河北省自然科学基金(C2011205061)
关键词
木质素
生物合成
转录因子
调控
lignin
biosynthesis
transcription factor
regulation
