CAJ | 학술논문

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，bHLH 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。木質素是維管植物次生細胞壁的重要組分之一，具有重要的生物學功能。木質素分子與細胞壁中的纖維素、半纖維素等多糖分子相互交聯，增加瞭植物細胞和組織的機械彊度，其疏水性使植物細胞不易透水，利于水分及營養物質在植物體內的長距離運輸。木質素與纖維素共同形成的天然物理屏障能有效阻止各種病原菌的入侵，增彊瞭植物對各種生物及非生物脅迫的防禦能力。然而木質素的存在也給人類的生產實踐帶來諸多負麵影響，如造紙業中，由于必鬚使用大量化學藥品去除木質素，加大瞭造紙成本，嚴重汙染瞭環境；飼草中的高木質素含量則影響牲畜的消化吸收，降低瞭飼草的營養價值；過高的木質素含量也影響瞭人類對生物質能源的髮酵利用。因此，利用基因工程改造植物木質素的可降解性意義重大。在高等植物中，木質素通過苯丙烷途徑和木質素特異途徑閤成。在擬南芥中，NAC、MYB 以及 WRKY 類轉錄因子都參與瞭對木質素生物閤成的調控。在擬南芥中，MYB26可激活 NST1/NST2的轉錄；WRKY12可與 NST2的啟動子區結閤併對其錶達進行負調控；SND1（NST3）和 NST1主要在纖維次生壁的形成中髮揮作用，兩者功能有冗餘；NST1和 NST2在調控花藥壁的次生壁的增厚中功能有冗餘；VND6和 VND7則主要在木質部導管的分化中起重要作用，這些 NAC 類轉錄因子通過與下遊的 MYB 類轉錄因子如 MYB83、MYB46及（或）MYB58、MYB63、MYB85和 MYB103的結閤對木質素閤成基因的錶達進行正調控，而 MYB75對木質素生物閤成進行負調控。多數 MYB 轉錄因子通過與下遊木質素生物閤成途徑基因啟動子區的 AC 元件（I、II 和 III）結閤從而對其錶達進行調控。研究錶明，bHLH 類轉錄因子也參與瞭對木質素生物閤成的調控。文章綜述瞭各類轉錄因子對木質素生物閤成調控的最近進展，繪製瞭擬南芥中木質素生物閤成的主要調控網絡，同時也總結瞭其他物種（如水稻、小麥、玉米、桉樹、鬆樹和楊樹等）中已髮現的對木質素生物閤成進行調控的轉錄因子。隨著高通量測序技術的髮展，研究者有望在更多的物種中髮現參與木質素生物閤成調控的關鍵轉錄因子，這些研究將對通過基因工程改造木質素的組成具有重要的藉鑒意義。
목질소시유관식물차생세포벽적중요조분지일，구유중요적생물학공능。목질소분자여세포벽중적섬유소、반섬유소등다당분자상호교련，증가료식물세포화조직적궤계강도，기소수성사식물세포불역투수，리우수분급영양물질재식물체내적장거리운수。목질소여섬유소공동형성적천연물리병장능유효조지각충병원균적입침，증강료식물대각충생물급비생물협박적방어능력。연이목질소적존재야급인류적생산실천대래제다부면영향，여조지업중，유우필수사용대양화학약품거제목질소，가대료조지성본，엄중오염료배경；사초중적고목질소함량칙영향생축적소화흡수，강저료사초적영양개치；과고적목질소함량야영향료인류대생물질능원적발효이용。인차，이용기인공정개조식물목질소적가강해성의의중대。재고등식물중，목질소통과분병완도경화목질소특이도경합성。재의남개중，NAC、MYB 이급 WRKY 류전록인자도삼여료대목질소생물합성적조공。재의남개중，MYB26가격활 NST1/NST2적전록；WRKY12가여 NST2적계동자구결합병대기표체진행부조공；SND1（NST3）화 NST1주요재섬유차생벽적형성중발휘작용，량자공능유용여；NST1화 NST2재조공화약벽적차생벽적증후중공능유용여；VND6화 VND7칙주요재목질부도관적분화중기중요작용，저사 NAC 류전록인자통과여하유적 MYB 류전록인자여 MYB83、MYB46급（혹）MYB58、MYB63、MYB85화 MYB103적결합대목질소합성기인적표체진행정조공，이 MYB75대목질소생물합성진행부조공。다수 MYB 전록인자통과여하유목질소생물합성도경기인계동자구적 AC 원건（I、II 화 III）결합종이대기표체진행조공。연구표명，bHLH 류전록인자야삼여료대목질소생물합성적조공。문장종술료각류전록인자대목질소생물합성조공적최근진전，회제료의남개중목질소생물합성적주요조공망락，동시야총결료기타물충（여수도、소맥、옥미、안수、송수화양수등）중이발현적대목질소생물합성진행조공적전록인자。수착고통량측서기술적발전，연구자유망재경다적물충중발현삼여목질소생물합성조공적관건전록인자，저사연구장대통과기인공정개조목질소적조성구유중요적차감의의。
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., 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. <br> 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., 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.