Silencing a phloretin-specific glycosyltransferase perturbs both general phenylpropanoid biosynthesis and plant development
Silencing a phloretin-specific glycosyltransferase perturbs both general phenylpropanoid biosynthesis and plant development
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DOI：
10.1111/tpj.13559
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发表时间：
2017-07-01
期刊：
影响因子：
7.2
通讯作者：
Atkinson, Ross G.
中科院分区：
文献类型：
--
作者：
Dare, Andrew P.;Yauk, Yar-Khing;Atkinson, Ross G.
苹果（Malusxapartica）的多酚类化合物主要是二氢查耳酮糖苷根皮苷，但其生理作用尚未阐明。根皮苷的生物合成作为主要苯丙素途径的侧分支发生，最后一步由根皮素特异性糖基转移酶UGT 88 F1介导。出乎意料的是，考虑到UGT有时被视为装饰酶，UGT 88 F1敲除系严重矮化，节间长度大大减少，叶片狭窄披针形，叶和果实细胞形态发生变化。这些变化表明，敲除系中生长素的运输发生了改变，这在转基因系中来自茎尖的生长素通量增加的测定中得到了证实。代谢物分析显示根皮素糖苷配基没有蓄积，许多非目标苯丙素类化合物也减少。这种代谢物积累的减少似乎是通过降低关键转录物水平（例如苯丙氨酸解氨酶，PAL）和酶活性（PAL和查耳酮合酶）抑制类苯丙素途径介导的。将外源根皮苷应用于组织培养中的UGT 88 F1敲除系，增强了轴向叶片的生长，并部分恢复了正常苹果叶片生长的某些方面。总之，我们的研究结果强烈暗示二氢查耳酮作为关键化合物在调节类苯丙素途径通量和建立生长素图案早期apple development.Significance声明苹果（Malusxapartica）的多酚配置文件是由二氢查耳酮糖苷根皮苷，然而，其生理作用尚未阐明。我们的研究结果表明，干扰根皮苷的积累影响正常的生长和发育，在苹果通过阻遏苯丙烷类途径和生长素运输的调制。
The polyphenol profile of apple (Malusxdomestica) is dominated by the dihydrochalcone glycoside phloridzin, but its physiological role is yet to be elucidated. Biosynthesis of phloridzin occurs as a side branch of the main phenylpropanoid pathway, with the final step mediated by the phloretin-specific glycosyltransferase UGT88F1. Unexpectedly, given that UGTs are sometimes viewed as decorating enzymes', UGT88F1 knockdown lines were severely dwarfed, with greatly reduced internode lengths, narrow lanceolate leaves, and changes in leaf and fruit cellular morphology. These changes suggested that auxin transport had been altered in the knockdown lines, which was confirmed in assays showing that auxin flux from the shoot apex was increased in the transgenic lines. Metabolite analysis revealed no accumulation of the phloretin aglycone, as well as decreases in many non-target phenylpropanoid compounds. This decreased accumulation of metabolites appeared to be mediated by the repression of the phenylpropanoid pathway via a reduction in key transcript levels (e.g. phenylalanine ammonia lyase, PAL) and enzyme activities (PAL and chalcone synthase). Application of exogenous phloridzin to the UGT88F1 knockdown lines in tissue culture enhanced axial leaf growth and partially restored some aspects of normal' apple leaf growth. Together, our results strongly implicate dihydrochalcones as critical compounds in modulating phenylpropanoid pathway flux and establishing auxin patterning early in apple development.Significance Statement The polyphenol profile of apple (Malusxdomestica) is dominated by the dihydrochalcone glycoside phloridzin, however, its physiological role is yet to be elucidated. Our results indicate that perturbing phloridzin accumulation affects normal growth and development in apple via repression of the phenylpropanoid pathway and modulation of auxin transport.