Chemical triggered defense mechanisms against Phytophthora infestans (original) (raw)
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Plant Pathology, 2008
Defence responses were investigated in two potato cultivars with different levels of resistance to late blight, Russet Burbank (susceptible) and Kennebec (moderately resistant), after inoculation with single isolates representing Phytophthora infestans genotypes US-1 (previously predominant, mildly aggressive) and US-8 (currently predominant, highly aggressive). The accumulation of brown lignin-like materials and an increase in the cell wall affinity to trypan blue 24 h after inoculation were observed in cv. Kennebec inoculated with US-1, but not in Kennebec inoculated with US-8, or cv. Russet Burbank inoculated with either US-1 or US-8. The expression of PAL-1, HMG-2, PR-1 and PR-5 was investigated in three leaf strata (local, proximal and distal) and at different times after inoculation, using SYBR real-time RT-PCR. The activation of these defence-related genes was affected not only by P. infestans genotype, but also by the potato cultivar and the proximity to the inoculation site. These genes were up-regulated earlier in Kennebec than in Russet Burbank and in response to US-1 than to US-8. Over all, the earliest and strongest up-regulation of these genes occurred in Kennebec inoculated with US-1. Furthermore, PAL-1 and HMG-2 were down-regulated at the site of infection while such downregulation was not observed for PR-1 or PR-5 . In parallel, the accumulation level and location of phenolics and rishitin matched those of PAL-1 and HMG-2 transcripts, respectively. These results strongly suggest that changes in either the activation or suppression of defence responses by the pathogen shape the level of susceptibility of potato cultivars to late blight.
Molecular plant-microbe interactions : MPMI, 2018
Phytophthora infestans causes the devastating potato late blight disease which is widely controlled with fungicides. However, the debate of chemical control is fueling a promotion towards alternative methods. In this context, the enhancement of natural plant immunity could be a strategy for more sustainable protection. We previously demonstrated that a Concentrated Culture Filtrate (CCF) of P.infestans primes defense reactions in potato. They are genotype-dependent, and metabolites produced decrease pathogen growth in vitro but not in vivo on tubers. Induced potato defenses are assumed to affect P.infestans life-history traits depending on strains. This assumption was studied in vivo through induced leaflets on a susceptible genotype inoculated with four P.infestans strains differing for lesion growth rate. This study combines both defenses mechanistic analysis and ecological observations. Defense genes expressions were thus assessed by qRT-PCR; pathogen development was simultaneous...
Activation of defence responses to Phytophthora infestans in potato by BABA
Plant Pathology, 2014
Late blight caused by Phytophthora infestans is one of the most devastating diseases of the potato crop. Resistance breeding and current fungicides are unable to control the rapidly evolving P. infestans and new control strategies are urgently needed. This study examined mechanisms of DL-b-aminobutyric acid (BABA)-induced resistance (IR) in the potato-P. infestans system. Leaves from two cultivars that differ in their degree of resistance, Bintje and Ovatio, were analysed after foliar treatment with BABA. Rapid activation of various defence responses and a significant reduction in P. infestans growth were observed in leaves treated with BABA. In the more resistant cultivar, Ovatio, the activation was both faster and stronger than in Bintje. Microscopic analysis of leaves treated with BABA revealed induction of small hypersensitive response (HR)-like lesions surrounded by callose, as well as production of hydrogen peroxide (H 2 O 2 ). Molecular and chemical analyses revealed soluble phenols such as arbutin and chlorogenic acid and activation of PR-1. These results show a direct activation of defence responses in potato, rather than priming as reported for other plant species. They also show that the efficiency of BABA-IR differs between cultivars, which highlights the importance of taking all aspects into consideration when establishing new methods for disease management.
Functional analysis of potato genes involved in quantitative resistance to Phytophthora infestans
Molecular Biology Reports, 2013
The most significant threat to potato production worldwide is the late blight disease, which is caused by the oomycete pathogen Phytophthora infestans. Based on previous cDNA microarrays and cDNA-amplified fragment length polymorphism analysis, 63 candidate genes that are expected to contribute to developing a durable resistance to late blight were selected for further functional analysis. We performed virus-induced gene silencing (VIGS) to these candidate genes on both Nicotiana benthamiana and potato, subsequently inoculated detached leaves and assessed the resistance level. Ten genes decreased the resistance to P. infestans after VIGS treatment. Among those, a lipoxygenase (LOX; EC 1.13.11.12) and a suberization-associated anionic peroxidase affected the resistance in both N. benthamiana and potato. Our results identify genes that may play a role in quantitative resistance mechanisms to late blight.
2019
SummaryPathogen recognition by plants via pathogen-associated molecular patterns leads to PAMP-triggered immunity. However, pathogens can modulate it via the secretion of effectors. We hypothesize that in potato, induced defense triggered by a Phytophthora infestans concentrated culture filtrate (CCF) could alter both effector expression and disease severity.CCF was sprayed onto three potato genotypes with different resistance levels, before inoculation with P. infestans. Symptoms were scored visually at 1-4 dpi, while the expression of defense and effector genes was assessed by qRT-PCR.CCF induced most defense genes in Désirée (PRs, EIN3) and Bintje (PRs, PAL and POX), but repressed most defense genes in Rosafolia. On the contrary, CCF induced most effector genes in Rosafolia (Pi03192, Avrblb2, Avr3a, EPIC2B and SNE1). INF1 was over-expressed in Bintje, despite its earlier expression in both Désirée and Rosafolia compared to unsprayed controls. Pi03192 was repressed in Désirée, and...
Plant Pathology, 2015
Quantitative resistance may depend on the effectiveness of PAMP-triggered immunity. This study highlights the diversity of mechanisms involved in the quantitative resistance of potato to Phytophthora infestans. The investigation focused on the implication of the hormone signalling pathways induced in four potato genotypes by a concentrated culture filtrate (CCF) of P. infestans. The genotypes were ranked according to their level of resistance to P. infestans and discriminant analysis of gene expression profiles separated the most resistant genotype from the three others, particularly because of a strong induction of the salicylic acid (SA) pathway. In this genotype, transcripts involved in the SA pathway, EDS1, WRKY1, PR-1 and PR-2, were induced by CCF. SA pathway involvement was confirmed by a peak of SA accumulation 12 h after elicitation and by the induction of jaz1 (jasmonate Zim domain protein 1) transcripts, which inhibit defence responses mediated by jasmonic acid (JA). By contrast, neither a significant induction of SA-mediated responses nor an accumulation of free SA and PR-2 were observed in the other resistant or two susceptible cultivars. Expression of genes in the ET and JA pathways was either not, or weakly, induced by CCF in potato. Finally, the involvement of signalling pathways was genotype dependent rather than correlating with resistance level.
Ethylicin Prevents Potato Late Blight by Disrupting Protein Biosynthesis of Phytophthora infestans
Pathogens
Phytophthora infestans, the causal agent of potato late blight, triggered the devastating Great Irish Famine that lasted from 1845 to 1852. Today, it is still the greatest threat to the potato yield. Ethylicin is a broad-spectrum biomimetic-fungicide. However, its application in the control of Phytophthora infestans is still unknown. In this study, we investigated the effects of ethylicin on Phytophthora infestans. We found that ethylicin inhibited the mycelial growth, sporulation capacity, spore germination and virulence of Phytophthora infestans. Furthermore, the integrated analysis of proteomics and metabolomics indicates that ethylicin may inhibit peptide or protein biosynthesis by suppressing both the ribosomal function and amino acid metabolism, causing an inhibitory effect on Phytophthora infestans. These observations indicate that ethylicin may be an anti-oomycete agent that can be used to control Phytophthora infestans.
Potato Late Blight is the main pathogen which affects potatoes. Due to unavailability of effective chemical control methods and the intensive use of fungicides, the introduction of resistant cultivars represents a safe strategy. The sources of horizontal resistance to Late Blight in the Argentinean Potato Breeding Programs have been varied. One of the interesting species to evaluate is Solanum tarijense since its adaptation to long days is promissory, producing tubers of good size and aspect. In this study, the enzymatic activity of different PR proteins in the specie S. tarijense was measured. These clones were more resistant to Late Blight than 'Bintje' and 'Pampeana INTA' cultivars. The activity of glucanases, chitinases, peroxidases and poliphenoloxidases were 15, 1.5, 2 and 3 times higher respectively, in S. tarijense than in 'Bintje' and 'Pampeana INTA'. These results suggest that some PR proteins can be used as biochemical markers to assist breeders in the selection of horizontal resistant cultivars.
Australian Journal of Crop Science
From the past late blight is one of the most dreaded diseases of potato worldwide. In this study, microarray-based gene expression was analysed in a late blight resistant Indian potato cultivar Kufri Girdhari upon Phytophthora infestans infection. A comprehensive transcriptional analysis was performed using cDNA microarrays, containing 70,083 ESTs (expressed sequence tag libraries) from plant leaf tissues collected at two stages: pre-inoculation (0 h, water spray as control) and post-inoculation (72 h after inoculation) by challenge inoculation of P. infestans. Microarray analysis using scatter plot revealed out of total statistically significant (P≤0.01) genes (#4622), a total of 2,344 resistance genes were up-regulated at post-inoculation stage compared to pre-inoculation. These significantly genes (#2,344) were greatly expressed at post-inoculation and contribute resistance in response to the challenge inoculation of P. infestans. Further, hierarchical clustering classified the genes (#2,344) expressions into 8 different clusters. Study revealed that molecular chaperones were found to be mainly controlling resistance mechanism in Kufri Girdhari and acted as downstream signalling pathway for defense related genes response to various mechanisms (stress/harmone/signalling genes/transporter/metabolism). The selected highly up-regulated genes were further validated for their expression in the cultivar by real-time (RT) PCR analysis. Thus study provides many candidate genes/transcripts for future characterization and functionality assay as initial starting point for research work.