3 research outputs found
Profiling and Localization of Stilbene Phytoalexins Revealed by MALDI-MSI during the Grapevine–Botrytis cinerea Interaction
Stilbene phytoalexins are among the most accumulated
compounds
during grapevine–pathogen interactions. However, their steady-state
accumulation level and spatial distribution within the tissues to
counteract Botrytis cinerea infection
remain to be explored. In this work, matrix-assisted laser desorption/ionization-mass
spectrometry imaging (MALDI-MSI) was used to determine the spatial
distribution of different phytoalexins in grapevine leaves upon infection
with B. cinerea. Ultraperformance liquid
chromatography-fluorescence (UPLC-FL) was also employed to monitor
the accumulation pattern of these phytoalexins. This study showed
that stilbene compounds accumulate in areas close to the pathogen
infection sites. It was also revealed that the accumulation patterns
of the stilbene phytoalexins can vary from one time point postinfection
to another with specific accumulation patterns within each time point.
To the best of our knowledge, this is the first time that the separate
localization of grapevine stilbene phytoalexins has been revealed
following B. cinerea infection
Table_1_Osmotic Stress and ABA Affect Immune Response and Susceptibility of Grapevine Berries to Gray Mold by Priming Polyamine Accumulation.DOCX
<p>Abiotic factors inducing osmotic stress can affect plant immunity and resistance against pathogen attack. Although a number of studies have characterized grapevine responses to various forms of biotic and abiotic stresses, the relationships between osmotic stress response and susceptibility of mature berries to Botrytis cinerea still remain unknown. In this study, we investigated the effects of osmotic stress and abscisic acid (ABA) on defense responses of mature grapevine berries before and after B. cinerea infection. We focused on the possible involvement of polyamines in the interaction between osmotic stress response and susceptibility to B. cinerea. We showed that osmotic stress induced by PEG or sucrose, and exogenous ABA induce transient but low defense responses, including weak expression of PR genes and phytoalexin synthesis in mature berries. This was accompanied by an upregulation of NCED2 involved in ABA biosynthesis and a large production of free polyamines. However, osmotic stress followed by B. cinerea infection primed berries for enhanced accumulation of polyamines, but slowed down the defense responses and increased susceptibility to the pathogen. A weak increase of diamine- and polyamine-oxidase activities was also recorded in stressed berries, but declined after pathogen infection. The pretreatment of stressed berries with appropriate inhibitors of diamine- and polyamine-oxidases further increased polyamine level and greatly lowered defense responses, leading to higher susceptibility to B. cinerea. These results suggest that increased polyamine titer through low activation of their oxidative degradation in grape berries may contribute at least in part to the weakening of defense responses and subsequent disease susceptibility.</p
<sup>13</sup>C NMR and LC-MS Profiling of Stilbenes from Elicited Grapevine Hairy Root Cultures
Resveratrol and related oligostilbenes
are defense molecules produced
by grapevine in response to stresses including various elicitors or
signal molecules. Together with their prominent role <i>in planta,</i> these compounds have been the center of much attention in recent
decades due to their pharmacological properties. The cost-effective
production of resveratrol derivatives such as viniferins or more structurally
complex stilbene oligomers remains a challenging task. In this study,
the chemical diversity of stilbenes produced by <i>Vitis vinifera</i> Pinot Noir hairy roots was investigated after elicitation for 4
days with a mixture of methyl jasmonate (100 μM) and cyclodextrins
(50 mM). Two crude extracts obtained from the culture medium and from
the hairy roots were fractionated by centrifugal partition chromatography.
The fractions were chemically investigated by two complementary identification
approaches involving a <sup>13</sup>C NMR-based dereplication method
and liquid chromatography coupled to mass spectrometry (LC-MS). In
total, groups of 21 and 18 molecules, including flavonoids and stilbenes,
were detected in the culture medium and root extracts, respectively.
These included resveratrol monomers, dimers, trimers, and a tetramer,
thus highlighting the ability of elicited hairy root culture systems
to synthesize a wide diversity of secondary metabolites of pharmaceutical
significance. The main compounds were unambiguously identified as <i>trans</i>-resveratrol, ε-viniferin, <i>trans</i>-piceatannol, pallidol, scirpusin A, eriodictyol, naringenin, vitisin
B, and maackin