p-Coumaroylation of poplar lignins impacts lignin structure and improves wood saccharification.
p-Coumaroylation of poplar lignins impacts lignin structure and improves wood saccharification.
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DOI：
10.1093/plphys/kiab359
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发表时间：
2021-11-03
期刊：
影响因子：
7.4
通讯作者：
Pilate G
中科院分区：
文献类型：
--
作者：
Lapierre C;Sibout R;Laurans F;Lesage-Descauses MC;Déjardin A;Pilate G
纤维素酶水解成葡萄糖，即糖化，受到木质素的严重阻碍。在野生型（WT）和过表达拟南芥（Arabidopsis thaliana）桂酸4-羟化酶（AtC4H）启动子驱动的对香豆油酰基辅酶A单脂醇转移酶1 （BdPMT1）基因的转基因杨树（Populus tremula × Populus alba）进行了分析。BdPMT1编码一种转移酶，该转移酶催化对香豆酸（pCA）对单脂醇的酰化。在温室中培养了几个BdPMT1- oe /WT和BdPMT1- oe /AtF5H-OE系，通过RT-PCR证实了BdPMT1在木质部的表达。对杨树干细胞壁（CWs）和相应纯化的二恶烷木质素（dl）的分析表明，BdPMT1-OE木质素与C3草秸秆的木质素一样被对香豆素化。在一些转化体中，pCA含量达到11 mg·g−1 CW和66 mg·g−1 DL，超过了短柄草和小麦（Triticum aestivum）样品的含量。这种前所未有的高木质素对香豆素酰化既不影响杨树的生长，也不影响树干的木质素含量。有趣的是，在BdPMT1-OE/AtF5H-OE转基因品系中，杨木木质素的对香豆素酰化并不有利，尽管它们的丁香基单位频率很高。然而，所有BdPMT1-OE系的木质素都发生了结构修饰，末端游离酚基增加。相对于对照，这种增加表明BdPMT1-OE木质素的聚合度降低，使它们更易于在冷NaOH溶液中溶解。杨树样品的对香豆素酰化提高了碱预处理CW的糖化率，表明木质素的遗传驱动的对香豆素酰化是一种很有前途的策略，可以使木质素更容易受到木质纤维素工业加工中使用的碱处理的影响。草对香豆醇-辅酶a：单脂醇转移酶的表达诱导了杨木素的高对香豆醇化，碱预处理杨木的糖化效果更好，而不影响生长。
The enzymatic hydrolysis of cellulose into glucose, referred to as saccharification, is severely hampered by lignins. Here, we analyzed transgenic poplars (Populus tremula × Populus alba) expressing the Brachypodium (Brachypodium distachyon) p-coumaroyl-Coenzyme A monolignol transferase 1 (BdPMT1) gene driven by the Arabidopsis (Arabidopsis thaliana) Cinnamate 4-Hydroxylase (AtC4H) promoter in the wild-type (WT) line and in a line overexpressing the Arabidopsis Ferulate 5-Hydroxylase (AtF5H). BdPMT1 encodes a transferase which catalyzes the acylation of monolignols by p-coumaric acid (pCA). Several BdPMT1-OE/WT and BdPMT1-OE/AtF5H-OE lines were grown in the greenhouse, and BdPMT1 expression in xylem was confirmed by RT-PCR. Analyses of poplar stem cell walls (CWs) and of the corresponding purified dioxan lignins (DLs) revealed that BdPMT1-OE lignins were as p-coumaroylated as lignins from C3 grass straws. For some transformants, pCA levels reached 11 mg·g−1 CW and 66 mg·g−1 DL, exceeding levels in Brachypodium or wheat (Triticum aestivum) samples. This unprecedentedly high lignin p-coumaroylation affected neither poplar growth nor stem lignin content. Interestingly, p-coumaroylation of poplar lignins was not favored in BdPMT1-OE/AtF5H-OE transgenic lines despite their high frequency of syringyl units. However, lignins of all BdPMT1-OE lines were structurally modified, with an increase of terminal unit with free phenolic groups. Relative to controls, this increase argues for a reduced polymerization degree of BdPMT1-OE lignins and makes them more soluble in cold NaOH solution. The p-coumaroylation of poplar samples improved the saccharification yield of alkali-pretreated CW, demonstrating that the genetically driven p-coumaroylation of lignins is a promising strategy to make wood lignins more susceptible to alkaline treatments used during the industrial processing of lignocellulosics. The expression of a grass p-coumaroyl-CoA:monolignol transferase induces high p-coumaroylation of poplar lignins and better saccharification of alkali-pretreated poplar wood without growth penalty.
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影响因子：
7.2
作者：
Franke, R;McMichael, CM;Chapple, C
通讯作者：
Chapple, C
影响因子：
7.4
作者：
Karlen, Steven D.;Free, Heather C. A.;Harris, Philip J.
通讯作者：
Harris, Philip J.
影响因子：
6.1
作者：
Lu, FC;Ralph, J
通讯作者：
Ralph, J
影响因子：
5.9
作者：
de Carvalho, Danila Morais;de Queiroz, Jose Humberto;Colodette, Jorge Luiz
通讯作者：
Colodette, Jorge Luiz
影响因子：
8.4
作者：
del Rio, Jose C.;Rencoret, Jorge;Ralph, John
通讯作者：
Ralph, John