Gallocatechin biosynthesis via a flavonoid 3′,5′-hydroxylase is a defense response in Norway spruce against infection by the bark for beetle-associated sap-staining fungus Endoconidiophora polonica
Gallocatechin biosynthesis via a flavonoid 3′,5′-hydroxylase is a defense response in Norway spruce against infection by the bark for beetle-associated sap-staining fungus Endoconidiophora polonica
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DOI：
10.1016/j.phytochem.2018.01.017
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发表时间：
2018-04-01
期刊：
影响因子：
3.8
通讯作者：
Gershenzon, Jonathan
中科院分区：
文献类型：
--
作者：
Hammerbacher, Almuth;Raguschke, Bettina;Gershenzon, Jonathan
挪威云杉（Picea abies）对真菌感染的最佳研究的防御反应之一是黄烷-3-醇的生物合成，其积累为称为原花色素的单体或聚合物。单个黄烷-3-醇单元由具有3 ′，4 ′-二羟基化B环的化合物[2，3-（反式）-（+）-儿茶素或2，3-（顺式）-（-）-表儿茶素]和具有3 ′，4 ′，5 ′-三羟基化B环的化合物[2，3（反式）-（+）-没食子儿茶素或2，虽然关于挪威云杉中儿茶素的生物合成和生物活性已知很多，但是关于没食子儿茶素或表没食子儿茶素的可比较的信息很少。我们发现，有一个显着增加的没食子儿茶素含量的挪威云杉树皮和木材接种后与小蠹相关的树液染色真菌Endoconiophora polonica。没食子儿茶素增加比例比儿茶素作为单体和聚合物的单元。在挪威云杉中鉴定的类黄酮3 '，5'-羟化酶基因通过在本氏烟草中异源表达而显示参与2，3（反式）-（+）-儿茶素转化为2，3（反式）-（+）-没食子儿茶素。挪威云杉的三羟基化B环是在黄酮-3-醇的水平上形成的，而不是像许多被子植物那样在二氢黄酮醇的水平上形成的。类黄酮3 '，5'-羟化酶基因的转录本丰度在真菌感染期间也显著增加，强调了其在没食子儿茶素生物合成中的重要性。比较2，3（反式）-（+）-儿茶素和2，3（反式）-（+）-没食子儿茶素对真菌生长的影响，发现2，3（反式）-（+）-儿茶素是真菌生长的较强抑制剂，而2，3（反式）-（+）-没食子儿茶素是黑色素生物合成的较强抑制剂。(C)2018爱思唯尔有限公司版权所有
One of the best-studied defense responses to fungal infection in Norway spruce (Picea abies) is the biosynthesis of fiavan-3-ols, which accumulate as monomers or polymers known as proanthocyanidins. The individual flavan-3-ol units consist of compounds with a 3',4'-dihydroxylated B ring [2,3-(trans)-(+)-catechin or 2,3-(cis)-(-)-epicatechin] and compounds with a 3',4',5'-trihydroxylated B ring [2,3 (trans)-(+)-gallocatechin or 2,3-(cis)-(-)-epigallocatechin].While much is known about the biosynthesis and biological activity of catechin in Norway spruce, there is little comparable information about gallocatechin or epigallocatechin. We found that there was a significant increase in the gallocatechin content of Norway spruce bark and wood after inoculation with the bark beetle-associated sap-staining fungus Endoconidiophora polonica. Gallocatechins increased proportionally more than catechins as both monomers and units of polymers. A flavonoid 3',5'-hydroxylase gene identified in Norway spruce was shown by heterologous expression in Nicotiana benthamiana to be involved in the conversion of 2,3 (trans)-(+)-catechin to 2,3 (trans)-(+)-gallocatechin. The formation of the trihydroxylated B ring in Norway spruce occurs at the level of fiavan-3-ols, rather than at the level of dihydroflavonols as in many angiosperms. The transcript abundance of the flavonoid 3',5'-hydroxylase gene also increased significantly during fungal infection underlining its importance in gallocatechin biosynthesis. Comparisons of the effect of 2,3 (trans)-(+)-catechin and 2,3 (trans)-(+)-gallocatechin on fungal growth revealed that 2,3 (trans)-(+)-catechin is a stronger inhibitor of fungal growth, while 2,3 (trans)-(+)-gallocatechin is a stronger inhibitor of melanin biosynthesis. (C) 2018 Elsevier Ltd. All rights reserved.