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1.
Hydrogen peroxide (H2O2) and lignin induced by acibenzolar-S-methyl (ASM) during the expression of systemic acquired resistance (SAR) of cucumber plants against the fungus Colletotrichum orbiculare was analysed with electron microscopy and energy-filtering electron microscopy (EFEM). ASM pretreatment consistently led to the blockage of appressorial penetration pegs into leaves at early stages after inoculation, whereas the fungus was able to grow into the vascular tissue after distilled water pretreatment. The blocked pegs, seen frequently at epidermal pectin layers in leaves of ASM-treated plants, were surrounded by abundant electron-dense amorphous material and dots. These were identified as lignin, based on their appearance and high reactivity with KMnO4. Lignin first appeared as an amorphous material at pectin layers, and then as dots in some areas of the material. The results showed that ASM caused SAR in leaves via faster formation of lignin within 1 day after inoculation. After CeCl3 treatment to detect H2O2, H2O2-reactive products (cerium perhydroxides) were seen near ASM-induced lignin formation sites in pectin layers. EFEM analysis showed that Ce and O were located at the same sites as the lignin dots, suggesting that lignin was associated with sources of H2O2 generation. The results indicate that the faster H2O2 generation and lignification induced by ASM were the potential causes of SAR. 相似文献
2.
The effect of two chemical elicitors (acibenzolar-S-methyl benzo-[1,2,3]- thiadiazole-7-carboxylic acid S-methyl ester [Boost
500SC]) and salicylic acid in inducing resistance in tea plants against blister blight disease caused by Exobasidium vexans Massee, was studied. Treatments with elicitors resulted in reduced severity of blister blight disease in nursery plants on
challenge with the pathogen. There was a significant increase in the activities of defense enzymes like phenylalanine ammonia
lyase, peroxidase and β-1,3-glucanase on elicitor treatments in tea leaves challenged with the pathogen than on unchallenged
leaves. Acibenzolar-S-methyl (ASM) at 0.14% registered the lowest disease severity (25.2%), whereas treatments with salicylic
acid were inferior. Under field conditions, the application of ASM at 0.14% resulted in disease protection of 25%. When ASM
was applied in alternate rounds with a standard fungicide, the disease protection improved to 46.8%. The importance of incorporating
ASM as a component in integrated disease management and also its importance in organic tea cultivation is discussed. 相似文献
3.
Chunlin Liu Ying Ruan Zongjun Lin Ran Wei Qi Peng Chunyun Guan Hideo Ishii 《Physiological and Molecular Plant Pathology》2008,72(4-6):141-145
In cucumber, we show salicylic acid only induce local acquired resistance (LAR), whereas acibenzolar-S-methyl (ASM) can induce LAR and systemic acquired resistance (SAR) to plant diseases. Jasmonic acid (JA) can induce local acquired susceptibility (LAS) and systemic acquired susceptibility (SAS). ASM treatment of lower first leaves leads to the accumulation of cucumber acidic class III chitinase (CHI2) in untreated upper leaves and effectively suppresses lesion formation on those leaves. In contrast, JA treatment completely suppresses CHI2 gene expression and causes plants to be more susceptible to Colletotrichum orbiculare. ASM-induced SAR can effectively antagonize the JA-induced SAS, providing a response that is midway between what would be expected with either JA or ASM by themselves. 相似文献
4.
Soichiro Morita Mikiko Azuma Toshiko Aoba Hiroya Satou Kazuhiko Narisawa Teruyoshi Hashiba 《Journal of General Plant Pathology》2003,69(1):71-75
The root endophytic fungus Heteroconium chaetospira isolate OGR-3 was tested for its ability to induce systemic resistance in Chinese cabbage against bacterial leaf spot caused
by Pseudomonas syringae pv. maculicola and Alternaria leaf spot caused by Alternaria brassicae of the foliar diseases. Chinese cabbage seedlings planted in soil infested with an isolate of H. chaetospira were incubated in a growth chamber for 32 days. The first to fourth true leaves of the seedlings were challenge-inoculated
with P. syringae pv. maculicola or A. brassicae. Chinese cabbage planted in soil infested with H. chaetospira showed significant decreases in the number of lesions of bacterial leaf spot or Alternaria leaf spot when compared to the
control plants not treated with H. chaetospira. The results indicated that colonization of roots by H. chaetospira could induce systemic resistance in Chinese cabbage and reduce the incidence of bacterial leaf spot and Alternaria leaf spot.
Received: April 24, 2002 / Accepted: August 9, 2002 相似文献
5.
Avia E. Rubin Ayelet-Chen Werdiger Mathias Blum Ulrich Gisi Helge Sierotzki Dietrich Hermann Yigal Cohen 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(2):339-351
Wild type (WT) field isolates of Bremia lactucae failed to germinate in vitro or infect lettuce leaves in the presence of CAA (carboxylic acid amide) fungicides. Minimal
inhibitory concentrations (MIC) for mandipropamid, dimethomorph, benthiavalicarb and iprovalicarb were 0.005, 0.5, 0.5 and
5 μg ml−1, respectively. Mutagenesis experiments showed that spores exposed to EMS (ethyl methane sulphonate) or UV irradiation (254 nm)
could infect lettuce leaves in the presence of up to 100 μg ml−1 CAA. The proportion of infected leaves relative to the number of spores inoculated (infection frequency) was inversely related
to the concentration of CAA used, ranging between 0 and 160 per 1 × 106 spores. Resistant mutants (RM) lost their resistance within 1–14 reproduction cycles on CAA-treated plants. Crosses were
made between RMxWT isolates and RMxRM isolates with an attempt to obtain stable homozygous resistant off-springs. Such crosses
yielded few resistant but unstable progeny isolates. Mutagenic treatments given to hybrid isolates also failed to produce
stable resistance. Previous gene sequencing data showed that stable resistance to CAAs is based on a single SNP in the cellulose synthase 3 (CesA3) gene of Plasmopara viticola. Therefore, we sequenced a 582 bp DNA fragment of Ces3A of WT, RM and hybrid isolates of B.lactucae. No mutation in this gene fragment was found. We conclude that mutagenic agents like EMS or UV may induce resistance to CAA
in Bremia lactucae but this resistance is not stable and not linked to mutations in CesA3 gene. 相似文献
6.
Ingerd S. Hofgaard Åshild Ergon Birgitte Henriksen Anne Marte Tronsmo 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(2):269-281
The effect of potential resistance inducing chemicals on disease development of Fusarium head blight was studied in winter wheat (Triticum aestivum L.). As a pre-screening test, the effect of different treatments on development of Microdochium majus (syn. Microdochium nivale var. majus) was studied in detached leaves. Based on these tests, DL-3-aminobutyric acid, Bion (benzo-(1,2,3) thiadiazole-7-carbothioic
acid S-methyl ester), and a foliar fertilizer containing potassium phosphite were selected for further studies. Greenhouse-grown
winter wheat was sprayed with aqueous solutions of the potential resistance inducers 7 days prior to Fusarium culmorum point inoculation of the heads. Disease development was registered as number of bleached spikelets per inoculated spike.
Spraying plants with the foliar fertilizer reduced the disease severity of F. culmorum by up to 40%. A reduced disease development of M. majus was also observed in detached leaves pre-treated with the foliar fertilizer. When the foliar fertilizer was added to the
growth medium, a reduced in vitro growth of M. majus and F. culmorum was observed, indicating that the effect on disease development is at least partly due to a fungistatic effect. No significant
reduction in disease development was observed in wheat pre-treated with DL-3-aminobutyric acid or Bion, although these compounds
tended to reduce disease development, especially when applied in combination with other potential resistance inducers. We
conclude that spraying winter wheat with a solution containing potassium phosphite can reduce development of M. majus and F. culmorum. 相似文献
7.
M. Bengtsson E. Wulff H. J. Lyngs Jørgensen A. Pham M. Lübeck J. Hockenhull 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(2):187-198
The effect of an extract of Yucca schidigera on the control and infection process of the apple scab pathogen, Venturia inaequalis, was examined and compared with the chemical resistance inducer, acibenzolar-S-methyl (ASM). In seedling assays, both materials significantly reduced apple scab symptoms and pathogen sporulation on leaves
and both showed similar control efficacies as the reference treatment, sulphur. Whereas yucca extract and sulphur gave significant
inhibition of conidial germination in vitro, ASM did not inhibit germination. Histopathological studies of the infection process of V. inaequalis in apple leaves showed that the yucca extract primarily acted by inhibiting pre-penetration events and penetration itself.
In contrast, the ASM treatment significantly inhibited more stages of the infection process (pre-penetration, penetration
and post-penetration events). These observations suggest that the yucca extract acted mainly by a direct fungitoxic effect
whereas ASM, as expected, acted as a resistance inducer. However, expression studies of two genes encoding the PR proteins,
PR1 and PR8, in apple seedlings indicated that yucca extract may also affect plant defence as expression of both genes was
up-regulated following yucca treatment, to a level similar to that observed after treatment with ASM. The fungitoxic effect
of sulphur on V. inaequalis was also confirmed in this study. 相似文献
8.
Fatma F. Abdel-Motaal Soad A. El-zayat Yuki Kosaka Magdi A. El-Sayed Rumi Kashima Yukie Maeda Mortada S. M. Nassar Shin-ichi Ito 《Journal of General Plant Pathology》2010,76(2):102-111
The antifungal activities of hyoscyamine and scopolamine, major alkaloids extracted from the desert plant Hyoscyamus muticus, against two rice pathogens, Magnaporthe oryzae and Rhizoctonia solani, were studied. The minimum inhibitory concentration of hyoscyamine that resulted in distinctive inhibition (MIC50) was 1 μg/ml for both fungi. Exposure to hyoscyamine caused the leakage of electrolytes from the mycelia of both fungi. Hyoscyamine
(>1 μg/ml) irreversibly delayed or inhibited conidial germination and appressorium formation in M. oryzae grown on polystyrene plates. Hyoscyamine effectively inhibited the attachment of conidia to the surface of rice (Oryza sativa) leaves and inhibited appressorium formation on the leaves. A high concentration of scopolamine (1000 μg/ml) also delayed
or inhibited conidial germination in M. oryzae, but conidial germination was restored after washing the conidia with water. Antifungal activity of hyoscyamine was reduced
by scopolamine. Magnaporthe oryzae infection was significantly suppressed (by >95%) in leaves of intact rice plants treated with hyoscyamine (10 μg/ml). Moreover,
10 μg hyoscyamine/ml significantly reduced the disease severity index for sheath blight to ≤0.2, when compared with the disease
index of control plants (>7.0). Hyoscyamine (>20 μg/ml) completely inhibited sclerotial germination and development of R. solani by delaying the initiation, maturation, and melanization of the sclerotia. These results suggest that tropane alkaloids may
be useful for controlling blast and sheath blight diseases of rice and for studying the mechanisms that regulate conidial
germination in M. oryzae and sclerotial germination and development in R. solani. 相似文献
9.
Resistance of Arabidopsis thaliana to Phelipanche aegyptiaca (syn. Orobanche aegyptiaca) can be induced by exposure of the host to low concentrations of gaseous methyl jasmonate, in a concentration-dependent fashion.
Application of methyl jasmonate at marginal concentrations, 10−8 M, for 12 h reduced infection by 50%. However, if the host plants were supplied with isoleucine at 10−3 M, and the isoleucine removed prior to exposure to methyl jasmonate, infection was reduced to less than 20%. The presence
of isoleucine throughout the experiment—before, during and after exposure to methyl jasmonate—reduced infection of the host
to almost zero. These results suggest that when Arabidopsis is exposed to methyl jasmonate, full activation of the defense mechanisms, including formation of the isoleucine jasmonic
acid conjugate, might be limited by the availability of isoleucine in the host. These findings add another factor to the complex
interaction between infecting parasite, and evocation of host defense mechanisms. 相似文献
10.
Sakhr Ajouz Marc Bardin Philippe C. Nicot Mohamed El Maâtaoui 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(1):31-42
Botrytis cinerea is able to build-up resistance to pyrrolnitrin, an antibiotic produced by diverse biocontrol agents, possibly compromising
the durability of this method of disease control. The development of two near-isogenic lines of B. cinerea differing in their level of resistance to pyrrolnitrin was compared in tomato plants and on PDA medium. In tomato plants,
significant differences in the percentage of infected petioles 1 day after inoculation and in symptom progression on petioles
and stems were observed between the resistant mutant and the sensitive wild-type parent, suggesting a difference in their
level of aggressiveness. Cytohistological investigations revealed that conidia of both near-isogenic lines germinated 6 h
after inoculation and mycelium developed within petiole tissues 12 h after inoculation. However, while the wild-type parent
isolate spread throughout the petiole and rapidly invaded the stem tissues via the leaf-abscission zone 72 h after inoculation, the pyrrolnitrin-resistant mutant failed to extend beyond petiole tissues
to invade the stem. Moreover, 72 h after inoculation, the mycelial development of the pyrrolnitrin-resistant mutant was accompanied
by abnormal glycogen accumulation and chlamydospore-like cell formation. In contrast, wild-type parent mycelium was normally
structured with intensive colonization of stem tissues. Additionally, on PDA medium the mycelium of the pyrrolnitrin-resistant
mutant was less vigorous than the wild-type isolate. These results suggest that the acquisition of pyrrolnitrin-resistance
in B. cinerea is accompanied by changes in mycelial structure and reduction in mycelial growth, leading to a noticeable loss of aggressiveness
on tomato plants. 相似文献
11.
Paula S. Coelho Luísa Valério António A. Monteiro 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(2):179-188
Downy mildew caused by the oomycete Hyaloperonospora parasitica (formerly Peronospora parasitica) is a worldwide foliar disease of Brassica vegetables, which may cause seedling loss in the nurseries and damage to adult
plants in the field. Disease symptoms start from the lower leaves and progress upwards. Three experiments were conducted under
controlled environment conditions, using inoculated leaf discs, to determine the influence of leaf position, plant age, and
leaf age on the expression of resistance to downy mildew in various Brassica oleracea genotypes. The upper leaves were more resistant than the lower leaves when 7–19 week-old plants of broccoli and Tronchuda
cabbage were tested. Broccoli lines ‘PCB21.32’ and ‘OL87123-2’ were fully susceptible at the cotyledon stage, showed a clear
resistance increase from lower to upper leaves at 6 weeks and ‘PCB21.32’ was fully resistant 16 weeks after sowing. Immature
leaves were more resistant than adjacent fully expanded mature leaves. Susceptibility increased with leaf age when the same
leaf was tested at two to 4-week intervals. Leaf age and upper-leaf position on the stem had opposite effects on disease score,
since younger leaves collected from lower positions and older leaves collected from upper positions tended to score similarly
in compatible interactions. The progression of downy mildew from the base of the plant upwards on B. oleracea in the field could be due to differences in leaf resistance in addition to environmental variation. To maximise the expression
of a compatible reaction in adult plants lower leaves of Brassica plants that are at least 12 weeks-old should be used. 相似文献
12.
Oliver A. H. Jones Mahon L. Maguire Julian L. Griffin Young-Ho Jung Junko Shibato Randeep Rakwal Ganesh K. Agrawal Nam-Soo Jwa 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(4):539-554
A metabolomics based approach has been used to study the infection of the Hwacheong rice cultivar (Oryza sativa L. cv. Hwacheong) with compatible (KJ201) and incompatible (KJ401) strains of the rice blast fungal pathogen Magnaporthe grisea. The metabolic response of the rice plants to each strain was assessed 0, 6, 12, 24, 36, and 48 h post inoculation. Nuclear
Magnetic Resonance (NMR) spectroscopy and Gas and Liquid Chromatography Tandem Mass spectrometry (GC/LC-MS/MS) were used to
study both aqueous and organic phase metabolites, collectively resulting in the identification of 93 compounds. Clear metabolic
profiles were observed at each time point but there were no significant differences in the metabolic response elicited by
each pathogen strain until 24 h post inoculation. The largest change was found to be in alanine, which was ~30% (±9%) higher
in the leaves from the compatible, compared to the resistant, plants. Together with several other metabolites (malate, glutamine,
proline, cinnamate and an unknown sugar) alanine exhibited a good correlation between time of fungal penetration into the
leaf and the divergence of metabolite profiles in each interaction. The results indicate both that a wide range of metabolites
can be identified in rice leaves and that metabolomics has potential for the study of biochemical changes in plant-pathogen
interactions. 相似文献
13.
A.M.Q. Lopez J.A. Lucas 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(5):409-420
The plant defence activators acibenzolar-S-methyl (Benzo[1,2,3]thiadiazole-7-carbothioic acid-S-methyl ester, ASM), 2,6-dichloro-isonicotinic acid (DCINA), salicylic acid (SA), and dibasic potassium phosphate (K2HPO4) were tested for their ability to protect cashew (Anacardium occidentale) seeds and leaves from anthracnose disease caused by Colletotrichum gloeosporioides. No inhibition of the early stages of pathogen development was caused by concentrations equal to or lower than 1.1mM a.i. ASM, 1.2mM a.i. DCINA, 5mM SA and 50mM K2HPO4. Maximum reduction of the disease in detached leaves, without phytotoxic effects, was obtained with 0.07mM a.i. ASM and DCINA, 5mM SA, and 50mM K2HPO4, with a time interval of at least 72h between application of the activator and inoculation with the pathogen. On attached leaves, foliar sprays were slightly more efficient than soil drench treatments, with 5mM SA being the most effective treatment, while 50mM SA as well as 0.3mM a.i. ASM and DCINA caused phytotoxic effects. In field-grown plants, protection was conferred by a soil drench of concentrations as low as 12.6M a.i. ASM and DCINA and 2.6mM SA. These concentrations were not phytotoxic suggesting that plant defence activators have potential for control of anthracnose disease in the field. 相似文献
14.
Pre-release techniques aim to increase the searching by the predators for their prey. Keeping bug predators for periods without
food before their release can increase the search ability of these insects. However, this practice can increase the cannibalism
during mass rearing. Brontocoris tabidus (Signoret) and Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) were kept for 12, 24, 36 and 48 h without food or with only Eucalyptus cloeziana plants in order to verify the occurrence of cannibalism on adults and eggs. Insects kept for periods longer than 24 h showed
higher cannibalism on adults and eggs and the presence of a E. cloeziana plant decreased the cannibalism during all the treatment periods. These predators preferred to attack first the eggs rather
than the adults, probably because of the inability of the former to avoid predation. The pre-release period should not exceed
24 h and plants must be provided to the predators in order to reduce the occurrence of cannibalism and increase the predatory
capacity of these natural enemies. 相似文献
15.
Francisco Alejo-Iturvide Maria Azucena Márquez-Lucio Isaías Morales-Ramírez Ma. Soledad Vázquez-Garcidueñas Víctor Olalde-Portugal 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(1):13-20
Hydrogen peroxide (H2O2) has been implicated in many stress conditions. Control of H2O2 levels is complex and dissection of mechanisms generating and relieving H2O2 stress is difficult, particularly in intact plants. Here the role of the mycorrhizal inoculation in chili plants challenged
with Phytophthora capsici was investigated to study the effect on hypersensitive response. In the treatment without mycorrhiza (treatment T3) and with
mycorrhiza (considered treatment T4) visible disorders were detected two days after inoculation with P. capsici, but in the next days T3 plants rapidly developed 25% more necrotic lesions on the leaves than T4 plants. Leaf necrosis correlated
with H2O2 accumulation and the greater damage observed in T3 plants coincided with larger accumulation of H2O2 after 12 h of inoculation accompanied with an increase in POX (peroxidase) and SOD (superoxide dismutase) activity. T4-infected
and mycorrhizal plants exhibited an earlier accumulation of H2O2 starting 6 h after inoculation with lower levels compared to T3 plants. Correlated with observed damage, POX and SOD activity
measured in T4 plants indirectly suggest a smaller accumulation of ROS (reactive oxygen species) leading to a decrease in
the wounds observed and slightly diminishing the advance of the pathogen. According to these findings, we conclude that mycorrhizal
colonization contributes significantly in maintaining the redox balance during oxidative stress, but the exact mechanism is
still uncertain. 相似文献
16.
Yongxiang Zhang Ewen M. Callaway Jeffrey B. Jones Mark Wilson 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(3):379-390
The plasmid pUFZ75 conferred constitutive GFP expression on the bacterial pathogen Xanthomonas euvesicatoria (syn. X. campestris pv. vesicatoria). Colonisation of the tomato phyllosphere and invasion of tomato leaves by X. euvesicatoria was examined using both fluorescence and confocal laser scanning microscopy. Xanthomonas euvesicatoria established a limited population on the tomato leaf surface, primarily occupying the depressions between epidermal cells
and around the stomata, prior to invasion of the leaf via the stomata and subsequent growth within the substomatal chamber
and the leaf apoplast. Additionally, hrp-gfp fusions were used to report on the temporal and spatial expression of hrp genes during epiphytic colonisation and invasion. Xanthomonas euvesicatoria cells carrying hrpG- and hrpX-gfp reporter constructs were not fluorescent in vitro on non-hrp-inducing LB agar but did exhibit a low level of fluorescence on the leaf surface within 24 h of inoculation, particularly
in the vicinity of stomata. Cells carrying hrpG- and hrpX-gfp fusions exhibited high levels of fluorescence 72 h after inoculation in the substomatal chamber and the leaf apoplast. Cells
carrying the hrpF-gfp fusion were slightly fluorescent on LB agar and showed no further increase in fluorescence on the leaf surface by 24 h after
inoculation, but did show a significant increase in fluorescence 72 h after inoculation in the substomatal chamber and apoplast.
The apparent low-level induction of the regulators hrpG and hrpX on the tomato leaf surface may suggest that some of the genes of the X. euvesicatoria HrpG/HrpX regulon are up- or down-regulated prior to invasion of the stomata while still on the leaf surface. 相似文献
17.
Dale R. Walters Linda Paterson Cecile Sablou David J. Walsh 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(1):73-82
It has been suggested that if plants in the field are already induced, their ability to further enhance induced resistance
might be compromised. This was examined in barley by inoculating the first two leaves with Rhynchosporium secalis prior to treatment of leaves three and four with an elicitor combination, followed by inoculation with R. secalis. The elicitor combination used consisted of acibenzolar-S-methyl, β-aminobutyric acid, and cis-jasmone, which was shown previously to provide higher levels of disease control in barley than any of the components used
individually. The elicitor combination reduced infection by R. secalis, and led to an up-regulation of PR1-b, a marker gene for systemic acquired resistance, and increased activities of the defence-related enzymes cinnamyl alcohol
dehydrogenase (CAD), peroxidase (POX), and β-1,3-glucanase. It also led to down-regulation of LOX2, a gene involved in biosynthesis of jasmonic acid. In plants where the first two leaves were inoculated with R. secalis prior to treatment of leaves three and four with elicitor, these increased defence responses did not occur, and control of
R. secalis infection on leaves three and four was also reduced. These results suggest that, at least in young barley plants, prior infection
with R. secalis compromises their ability to respond effectively to elicitors. The results might help to explain the relatively poor performance
of induced resistance in the field, particularly in cereals, compared to plants grown under controlled conditions. 相似文献
18.
19.
Application of 0.1 and 0.2 mM salicylic acid (SA) significantly reduced take-all disease caused by Gaeumannomyces graminis var. tritici (Ggt) and increased the root and shoot lengths and biomass, whereas 0.5 and 1 mM SA had no significant effect. The effective SA
concentrations also increased the activities of soluble peroxidase (SPOX) and cell-wall-bound peroxidase (CWPOX) and the concentration
of total phenolic compounds. SPOX activity was highest at days 4 and 3 in healthy roots and those inoculated with Ggt, respectively, and that of CWPOX at day 6 in both healthy and inoculated roots. The concentration of phenolic compound was
also highest at day 3 in both healthy roots and those inoculated with Ggt. The results indicate that the protective effect of SA depends on certain concentrations which increase peroxidase activity
and phenolic compounds accumulation in the wheat roots; higher SA concentrations did not differ from the controls. 相似文献
20.
H. D. Mbouobda Fotso P. F. Djocgoue N. D. Omokolo I. El Hadrami T. Boudjeko 《Phytoparasitica》2010,38(1):71-79
The root rot disease caused by Pythium myriotylum is responsible for about 70% of cocoyam production loss in Cameroon. The potential of benzo-(1,2,3)-thiadiazole-7-carbothioic
S-methyl ester (BTH) to trigger resistance in cocoyam (Xanthosoma sagittifolium) plants against P. myriotylum was investigated. Under controlled conditions, BTH was an efficient elicitor of some defense reactions in cocoyam. Application
of 0.2 mg ml−1 of BTH on leaves 7 days before inoculation of roots with P. myriotylum enhanced the activities of peroxidase (Pox) and polyphenoloxidase (PPO) as well as the total phenolic content. This resistance
was noted as a decrease in disease incidence and severity in BTH-treated plants. This increase in Pox activities was correlated
with two new isoforms in a white (sensitive) cultivar inoculated after stimulation. In a yellow (resistant) cultivar, stimulation
was characterized by the appearance of one isoform. Qualitative analysis of phenolic compounds by HPLC showed an increase
of hydroxycinnamic and flavonoid derivatives after inoculation. We also observed the appearance of a new caffeoylshikimic
acid derivative after stimulation followed by inoculation of both cultivars. The findings indicated that the pattern of induction
is different and depends on the variety. 相似文献