Transgenic apple plants overexpressing the chalcone 3-hydroxylase gene of Cosmos sulphureus show increased levels of 3-hydroxyphloridzin and reduced susceptibility to apple scab and fire blight.
Transgenic apple plants overexpressing the chalcone 3-hydroxylase gene of Cosmos sulphureus show increased levels of 3-hydroxyphloridzin and reduced susceptibility to apple scab and fire blight.
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DOI：
10.1007/s00425-016-2475-9
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发表时间：
2016-05
期刊：
影响因子：
4.3
通讯作者：
Halbwirth H
中科院分区：
文献类型：
--
作者：
Hutabarat OS;Flachowsky H;Regos I;Miosic S;Kaufmann C;Faramarzi S;Alam MZ;Gosch C;Peil A;Richter K;Hanke MV;Treutter D;Stich K;Halbwirth H
查耳酮-3-羟化酶的过表达引起苹果属植物中3-羟基根皮苷积累的增加。观察到类黄酮浓度降低，但类黄酮类成分不变。3-羟基根皮苷含量的增加与对火疫病和疮痂病的敏感性降低密切相关。二氢查耳酮在苹果防御机制对病原体的参与进行了讨论，但未知的生物合成步骤，在其形成阻碍其生理相关性的研究。3-羟基根皮素的形成是该途径中的缺口之一。可能涉及多酚氧化酶和细胞色素P450依赖酶。根皮素3位羟基化反应与黄酮类化合物3′-羟化酶（F3′H）催化的B环羟基化反应具有高度的相似性。使用来自Cosmos sulphureus的重组F3 'H和查耳酮3-羟化酶（CH 3 H），我们表明F3' H和CH 3 H在一定程度上接受根皮素，但CH 3 H获得更高的转化率。为了测试CH 3 H是否催化植物中二氢查耳酮的羟基化，以及这是否具有生理相关性，我们创建了携带来自C.硫磺。获得的三个转基因株系表现出较低的多酚浓度，但主要的多酚类二氢查耳酮，黄酮醇，羟基肉桂酸和黄烷3-醇之间没有变化。增加3-羟基根皮苷内的二氢查耳酮和表儿茶素/儿茶素内的可溶性黄烷3-醇进行了观察。二氢黄酮醇4-还原酶和查耳酮合成酶/查耳酮异构酶的活性降低可以部分解释较低的多酚浓度。与亲本相比，转CH 3 H基因株系对火疫病和苹果黑星病的感病性降低，这与3-羟基根皮苷含量的增加有关。本文的在线版本（doi：10.1007/s 00425 -016-2475-9）包含补充材料，可供授权用户使用。
Overexpression of chalcone-3-hydroxylase provokes increased accumulation of 3-hydroxyphloridzin inMalus. Decreased flavonoid concentrations but unchanged flavonoid class composition were observed. The increased 3-hydroxyphlorizin contents correlate well with reduced susceptibility to fire blight and scab. The involvement of dihydrochalcones in the apple defence mechanism against pathogens is discussed but unknown biosynthetic steps in their formation hamper studies on their physiological relevance. The formation of 3-hydroxyphloretin is one of the gaps in the pathway. Polyphenol oxidases and cytochrome P450 dependent enzymes could be involved. Hydroxylation of phloretin in position 3 has high similarity to the B-ring hydroxylation of flavonoids catalysed by the well-known flavonoid 3′-hydroxylase (F3′H). Using recombinant F3′H and chalcone 3-hydroxylase (CH3H) from Cosmos sulphureus we show that F3′H and CH3H accept phloretin to some extent but higher conversion rates are obtained with CH3H. To test whether CH3H catalyzes the hydroxylation of dihydrochalcones in planta and if this could be of physiological relevance, we created transgenic apple trees harbouring CH3H from C. sulphureus. The three transgenic lines obtained showed lower polyphenol concentrations but no shift between the main polyphenol classes dihydrochalcones, flavonols, hydroxycinnamic acids and flavan 3-ols. Increase of 3-hydroxyphloridzin within the dihydrochalcones and of epicatechin/catechin within soluble flavan 3-ols were observed. Decreased activity of dihydroflavonol 4-reductase and chalcone synthase/chalcone isomerase could partially explain the lower polyphenol concentrations. In comparison to the parent line, the transgenic CH3H-lines showed a lower disease susceptibility to fire blight and apple scab that correlated with the increased 3-hydroxyphlorizin contents. The online version of this article (doi:10.1007/s00425-016-2475-9) contains supplementary material, which is available to authorized users.