Petri, C. | Search bioRxiv

bioRxiv2017

The effect of abiotic and biotic stress on the salicylic acid biosynthetic pathway from mandelonitrile in peach

HighlightWe show that the recently suggested third pathway for SA biosynthesis from mandelonitrile in peach is also functional under both abiotic and biotic stress conditions.\n\nAbstractSalicylic acid (SA) plays a central role in plant responses to environmental stresses via the SA-mediated regulation of many metabolic and molecular processes. In a recent study, we suggested a third pathway for SA biosynthesis from mandelonitrile (MD) in peach plants. This pathway is alternative to the phenylalanine ammonia-lyase pathway and links SA biosynthesis and cyanogenesis. In the present work, we show that this new SA biosynthetic pathway is also functional under abiotic (salt) and biotic (Plum pox virus infection) stress conditions, although the contribution of this pathway to the SA pool does not seem to be important under such conditions. Treating peach plants with MD not only affected the SA content, but it also had a pleiotropic effect on abscisic acid and jasmonic acid levels, two well-known stress related hormones, as well as on the H2O2-related antioxidant activities. Furthermore, MD improved plant performance under the stressful conditions, probably via the activation of different signaling pathways. We have thus proven that SA is not limited to biotic stress responses, but that it also plays a role in the response to abiotic stress in peach, although the physiological functions of this new SA biosynthetic pathway from MD remain to be elucidated.\n\nAbbreviations

plant biology↗

bioRxiv2017

Metabolomics and biochemical approaches link salicylic acid biosynthesis to cyanogenesis in peach plants

HighlightMandelonitrile, and hence cyanogenic glycosides turnover, is involved in salicylic acid (SA) biosynthesis in peach plants under control and stress conditions. A third pathway for SA synthesis in peach is proposed.\n\nAbstractDespite the long-established importance of salicylic acid (SA) in plant stress responses and other biological processes, its biosynthetic pathway has not been fully characterized. The proposed SA synthesis originates from chorismate by two distinct pathways: isochorismate and penhylalanine (Phe) ammonia-lyase (PAL) pathways. Cyanogenesis is the process related to the release of hydrogen cyanide from endogenous cyanogenic glycosides (CNglcs), and it has been linked to plant plasticity improvement. To date, however, no relationship has been suggested between both pathways. In this work, by metabolomics and biochemical approaches (including [13C]-labelled compounds), we provide evidences showing that CNglcs turnover is involved, at least in part, in SA biosynthesis in peach plants under control and stress conditions.\n\nThe main CNglcs in peach are prunasin and amygdalin, with mandelonitrile (MD), synthesized from Phe, controlling their turnover. In peach plants MD is at the hub of the suggested new SA biosynthetic pathway and CNglcs turnover, regulating both the amygdalin and SA biosynthesis. MD-treated peach plants displayed increased SA levels via benzoic acid (SA precursor). In addition, MD also provides partial protection against Plum pox virus infection in peach seedlings. Thus, we proposed a third pathway, alternative to the PAL pathway, for SA synthesis in peach plants.

physiology↗