Salicylic acid (SA) plays a central role in plant responses to environmental stresses. In a recent study, we suggested a third pathway for SA biosynthesis from mandelonitrile (MD) in peach plants. This pathway is an alternative to the phenylalanine ammonia-lyase pathway and links SA biosynthesis and cyanogenesis. In the present work, using biochemical approaches, we studied the effect of salt stress and Plum pox virus (PPV) infection on this proposed SA biosynthetic pathway from MD. Peach plants were submitted to salt stress and Plum pox virus (PPV) infection. We studied the levels of SA and its intermediates/precursors (phenylalanine, MD, amygdalin and benzoic acid) in in vitro shoots. Moreover, in peach seedlings, we analysed the content of H2 O2 -related enzymes, SA and the stress-related hormones abscisic acid and jasmonic acid. We showed that the contribution of this SA biosynthetic pathway from MD to the total SA pool does not seem to be important under the stress conditions assayed. Nevertheless, MD treatment not only affected the SA content, but also had a pleiotropic effect on abscisic acid and jasmonic acid levels. Furthermore, MD modulates the antioxidative metabolism via SA-dependent or -independent redox-related signalling pathways. Even though the proposed SA biosynthetic pathway seems to be functional under stress conditions, MD, and hence cyanogenic glycosides, may be operating more broadly than by influencing SA pathways and signalling. Thus, the physiological function of the proposed SA biosynthetic pathway remains to be elucidated.

中文翻译：

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胁迫条件对桃中水杨酸相关的水杨酸生物合成影响的生化研究。

水杨酸（SA）在植物对环境胁迫的反应中起着核心作用。在最近的研究中，我们提出了桃植物中由扁桃腈（MD）进行SA生物合成的第三条途径。该途径是苯丙氨酸氨裂合酶途径的替代途径，并将SA的生物合成和发蓝联系起来。在目前的工作中，我们使用生化方法研究了盐胁迫和梅花病毒（PPV）感染对从MD提出的SA生物合成途径的影响。桃树遭受盐胁迫和李子痘病毒（PPV）感染。我们研究了离体芽中SA及其中间体/前体（苯丙氨酸，MD，苦杏仁苷和苯甲酸）的水平。此外，在桃子幼苗中，我们分析了H2 O2相关酶，SA以及胁迫相关激素脱落酸和茉莉酸的含量。我们表明，在测定的胁迫条件下，从MD到总SA库的SA SA生物合成途径的贡献似乎并不重要。然而，MD处理不仅影响SA含量，而且对脱落酸和茉莉酸水平具有多效性作用。此外，MD通过SA依赖性或非依赖性氧化还原相关的信号传导途径调节抗氧化代谢。尽管拟议的SA生物合成途径似乎在胁迫条件下起作用，但MD以及因此产生的氰苷可能比通过影响SA途径和信号传导更广泛地发挥作用。因此，拟议的SA生物合成途径的生理功能仍有待阐明。