Cross-talk interactions of exogenous nitric oxide and sucrose modulates phenylpropanoid metabolism in yellow lupine embryo axes infected with Fusarium oxysporum

AbstractThe aim of the study was to examine cross-talk of exogenous nitric oxide (NO) and sucrose in the mechanisms of synthesis and accumulation of isoflavonoids in embryo axes of Lupinus luteus L. cv. Juno. It was verified whether the interaction of these molecules can modulate the defense response of axes to infection and development of the pathogenic fungus Fusarium oxysporum f. sp. lupini. Sucrose alone strongly stimulated a high level of genistein glucoside in axes pretreated with exogenous nitric oxide (SNP or GSNO) and non-pretreated axes. As a result of amplification of the signal coming from sucrose and GSNO, high isoflavonoids accumulation was observed (+Sn+GSNO). It needs to be stressed that infection in tissues pretreated with SNP/GSNO and cultured on the medium with sucrose (+Si+SNP/+Si+GSNO) very strongly enhances the accumulation of free isoflavone aglycones. In +Si+SNP axes phenylalanine ammonia-lyase activity was high up to 72h. As early as at 12h in +Si+SNP axes an increase was recorded in gene expression level of the specific isoflavonoid synthesis pathway. At 24h in +Si+SNP axes a very high total antioxidant capacity dependent on the pool of fast antioxidants was noted. Post-infection generation of semiquinone radicals was lower in axes with a high level of sucrose than with a deficit

BABA-Primed Histone Modifications in Potato for Intergenerational Resistance to Phytophthora infestans

In this paper we analyzed β-aminobutyric acid (BABA)-primed epigenetic adjustment of potato cv. “Sarpo Mira” to Phytophthora infestans. The first stress-free generation of the potato genotype obtained from BABA-primed parent plants via tubers and seeds showed pronounced resistance to the pathogen, which was tuned with the transcriptional memory of SA-responsive genes. During the early priming phase before the triggering stress, we found robust bistable deposition of histone marks (H3K4me2 and H3K27me3) on the NPR1 (Non-expressor of PR genes) and the SNI1 gene (Suppressor of NPR1, Inducible), in which transcription antagonized silencing. Switchable chromatin states of these adverse systemic acquired resistance (SAR) regulators probably reprogrammed responsiveness of the PR1 and PR2 genes and contributed to stress imprinting. The elevated levels of heritable H3K4me2 tag in the absence of transcription on SA-dependent genes in BABA-primed (F0) and its vegetative and generative progeny (F1) before pathogen challenge provided evidence for the epigenetic mark for intergenerational memory in potato. Moreover, our study revealed that histone acetylation was not critical for maintaining BABA-primed defense information until the plants were triggered with the virulent pathogen when rapid and boosted PRs gene expression probably required histone acetyltransferase (HAT) activity both in F0 and F1 progeny

BABA-Induced DNA Methylome Adjustment to Intergenerational Defense Priming in Potato to Phytophthora infestans

We provide evidence that alterations in DNA methylation patterns contribute to the regulation of stress-responsive gene expression for an intergenerational resistance of β-aminobutyric acid (BABA)-primed potato to Phytophthora infestans. Plants exposed to BABA rapidly modified their methylation capacity toward genome-wide DNA hypermethylation. De novo induced DNA methylation (5-mC) correlated with the up-regulation of Chromomethylase 3 (CMT3), Domains rearranged methyltransferase 2 (DRM2), and Repressor of silencing 1 (ROS1) genes in potato. BABA transiently activated DNA hypermethylation in the promoter region of the R3a resistance gene triggering its downregulation in the absence of the oomycete pathogen. However, in the successive stages of priming, an excessive DNA methylation state changed into demethylation with the active involvement of potato DNA glycosylases. Interestingly, the 5-mC–mediated changes were transmitted into the next generation in the form of intergenerational stress memory. Descendants of the primed potato, which derived from tubers or seeds carrying the less methylated R3a promoter, showed a higher transcription of R3a that associated with an augmented intergenerational resistance to virulent P. infestans when compared to the inoculated progeny of unprimed plants. Furthermore, our study revealed that enhanced transcription of some SA-dependent genes (NPR1, StWRKY1, and PR1) was not directly linked with DNA methylation changes in the promoter region of these genes, but was a consequence of methylation-dependent alterations in the transcriptional network

Insights into the expression of DNA (de)methylation genes responsive to nitric oxide signaling in potato resistance to late blight disease

Our previous study concerning the pathogen-induced biphasic pattern of nitric oxide (NO) burst revealed that the decline phase and a low level of NO, due to S-nitrosoglutathione reductase (GSNOR) activity, might be decisive in the upregulation of stress-sensitive genes via histone H3/H4 methylation in potato leaves inoculated with avr P. infestans. The present study refers to the NO-related impact on genes regulating DNA (de)methylation, being in dialog with histone methylation. The excessive amounts of NO after the pathogen or GSNO treatment forced the transient upregulation of histone SUVH4 methylation and DNA hypermethylation. Then the diminished NO bioavailability reduced the SUVH4-mediated suppressive H3K9me2 mark on the R3a gene promoter and enhanced its transcription. However, we found that the R3a gene is likely to be controlled by the RdDM methylation pathway. The data revealed the time-dependent downregulation of the DCL3, AGO4, and miR482e genes, exerting upregulation of the targeted R3a gene correlated with ROS1 overexpression. Based on these results, we postulate that the biphasic waves of NO burst in response to the pathogen appear crucial in establishing potato resistance to late blight through the RdDM pathway controlling R gene expression

Rozwój Botrytis cinerea Pers. ex Fr. na liściach wilczomlecza pięknego (Euphorbia pulcherrima Willd.) [Development of Botrytis cinerea Pers. ex Fr. on leaves of common poinsettia (Euphorbia pulcherrima Willd.)]

The development of Botrytis cinerea was assessed on six cultivars of common poinsettia, differing in the colour of bracts, and being in great demand among buyers of these ornamental plants. Resistance to this pathogen differed in the investigated poinsettias. Cultivar 'Malibu Red' (red bracts) turned out to be most susceptible, while cv. 'Marblestar' (cream-pink) and cv. 'Coco White' (white) - relatively resistant to this fungus. After application of various inoculation methods (leaf discs, cut off leaves, whole plants) the differences in resistance to B. cinerea were confirmed for two extreme cultivars - susceptible ('Malibu Red') and resistant ('Coco White'), which indicated genetic background of this polymorphism. The rate of disease development on poinsettia leaves was affected by the amount of spores used for inoculation (optimum density of 3.5·105 B. cinerea conidia / ml suspension) and the addition of stimulants (0.1 M glucose with 0.05 M KH2PO4), which facilitated germination and infection of the host tissue. The inoculated poinsettia leaves showed high stability of plasma membranes. In the susceptible cultivar, in spite of the development of necrotic spots, a significant increase in the membrane damage index (by 13%) was found only on day 7 of the disease development

Wpływ syntetycznych induktorów odporności nabytej na hamowanie rozwoju szarej pleśni u pelargonii i poinsecji [The effect of synthetic inducers of systemic resistance in inhibiting grey mold development on geranium and poinsettia]

Several chemical activators of resistance were tested to evaluate their efficiency in restricting development caused by Botryotinia fuckeliana (Botrytis cinerea) on geranium and poinsettia leaves. The used signal pathway inducers of salicylic acid, such as DL-â-aminobutyric acid (BABA), g-aminobutyric acid (GABA) and benzothiadiazole (BTH), at the applied rates markedly inhibited the development of grey mould in the both plant species. The mentioned inducers showed no toxic or restricting effect on the fungus growth and development under in vitro conditions. Only methyl jasmonate (Me-JA), a potential activator of independent signal transduction pathway, at the applied quantities (O,1–1,0 mg·ml-1), noticeably enhanced the disease spot development probably through stimulation of ethylene synthesis in plant. Me-JA added to medium with B.cinerea showed a strong antifungal action, whereas ethylene significantly stimulated mycelium growth in the in vitro cultures

Water deficit-induced membrane injury and oxidative stress in two barley genotypes

The purpose of this paper was to examine the effect of water deficit on membrane injuries, superoxide radical generation and lipid peroxidation in the leaves of two barley genotypes. Six-day-old seedlings of the cv. Aramir and line R567 were used in the experiments. According to our earlier work these genotypes significantly differ in the level of membrane injuries under water deficit conditions. Water stress was applied directly to leaves or to roots. The stress caused considerable membrane injuries in the leaves of all genotypes investigated.The percentage membrane injury was higher in the line R567 than in the cv. Aramir. Water stress imposed on leaves caused higher membrane injuries than water stress imposed on roots. The water stress treatment followed by an oxidative stress in the leaves. Line R567 having noticeably larger membrane injuries also exhibited a higher level of superoxide radical generation than the cv. Aramir. The level of lipid peroxidation increased in the both genotypes under the conditions of water stress imposed on leaves, but not on roots

Contrasting Regulation of NO and ROS in Potato Defense-Associated Metabolism in Response to Pathogens of Different Lifestyles.

Our research provides new insights into how the low and steady-state levels of nitric oxide (NO) and reactive oxygen species (ROS) in potato leaves are altered after the challenge with the hemibiotroph Phytophthora infestans or the necrotroph Botrytis cinerea, with the subsequent rapid and invader-dependent modification of defense responses with opposite effects. Mainly in the avirulent (avr) P. infestans-potato system, NO well balanced with the superoxide level was tuned with a battery of SA-dependent defense genes, leading to the establishment of the hypersensitive response (HR) successfully arresting the pathogen. Relatively high levels of S-nitrosoglutathione and S-nitrosothiols concentrated in the main vein of potato leaves indicated the mobile function of these compounds as a reservoir of NO bioactivity. In contrast, low-level production of NO and ROS during virulent (vr) P. infestans-potato interactions might be crucial in the delayed up-regulation of PR-1 and PR-3 genes and compromised resistance to the hemibiotrophic pathogen. In turn, B. cinerea triggered huge NO overproduction and governed inhibition of superoxide production by blunting NADPH oxidase. Nevertheless, a relatively high level of H2O2 was found owing to the germin-like activity in cooperation with NO-mediated HR-like cell death in potato genotypes favorable to the necrotrophic pathogen. Moreover, B. cinerea not only provoked cell death, but also modulated the host redox milieu by boosting protein nitration, which attenuated SA production but not SA-dependent defense gene expression. Finally, based on obtained data the organismal cost of having machinery for HR in plant resistance to biotrophs is also discussed, while emphasizing new efforts to identify other components of the NO/ROS cell death pathway and improve plant protection against pathogens of different lifestyles

The Effects of Pharmacological Carbonic Anhydrase Suppression on Defence Responses of Potato Leaves To Phytophthora Infestans

In this study we proposed carbonic anhydrase (CA) as an important element of basal resistance during the potato (Solanum tuberosum L.)-Phytophthora infestans interaction. We found a different β-CA expression pattern in incompatible vs. compatible systems correlated in time with CA enzyme activity. Resistant potato leaves supplied with dorzolamide (an inhibitor of carbonate CA activity) and challenged with the pathogen showed an elevated nitric oxide (NO) synthesis, which was the most evident during the early phase of NO burst (at 3 hpi) during hypersensitive response (HR). In vitro application of dorzolamide and effective inhibitors of NO synthesis confirmed the implication of CA activity in NO metabolism during potato defense. To clarify how suppression of CA carbonate activity translates into the complexity of NO-related responses leading to potato resistance or susceptibility to an oomycete pathogen we analysed expression of NPR, PR1, and PAL. Taken together, pharmacological damping of CA activity revealed a functional link between CA and NO-dependent signaling in potato defense against P. infestans manifested by accelerated NO formation and a modified salicylic acid defense pathway. The dorzolamide-mediated effective responses for basal resistance also delayed symptoms of late blight in the susceptible potato cultivar, without overcoming HR formation in the resistant one