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1.
为了解橡胶树2种炭疽病菌的侵染结构发育分化过程,采用平板菌落生长速率法测定了3株胶孢炭疽菌Colletotrichum gloeosporioides和3株尖孢炭疽菌C.acutatum的菌丝生长速率,测量其分生孢子大小,显微观察2种炭疽菌在疏水表面诱导下侵染结构的发育分化过程。结果表明,胶孢炭疽菌菌丝生长速率为0.96~1.36 cm/d,显著高于尖孢炭疽菌的菌丝生长速率0.72~0.89 cm/d,但二者分生孢子大小无显著差异。在疏水表面诱导下,2种炭疽菌分生孢子在接种2~6 h后开始萌发,12 h孢子萌发率为71.70%~88.05%,13~16 h开始分化附着胞,24 h附着胞形成率为48.99%~70.74%,36 h菌丝诱发形成大量附着枝,48 h后分生孢子产生的次生菌丝也可诱发形成附着枝,附着枝呈圆形、姜瓣形、梨形或不规则形。分生孢子极易产生,可在菌丝顶端成簇或菌丝侧面排列产生,也可由分生孢子形成的芽管产生,或在芽管分化附着胞过程分枝形成分生孢子;附着胞多着生于芽管顶端,少数附着胞顶端可继续萌发类似短芽管结构,再次分化形成可黑色化的次级附着胞。表明橡胶树2种炭疽菌不同菌株间分生孢子萌发时间、孢子萌发率、附着胞形成时间和形成率有一定差异,但种间无明显差异;橡胶树炭疽菌分生孢子极易形成,在疏水表面容易分化形成附着胞和附着枝,说明具有极强的适生性。 相似文献
2.
ABSTRACT To explore the potential for nontoxic crop protection technologies based on the inhibition of fungal spore adhesion, we have tested the effect of synthetic zosteric acid (p-(sulfo-oxy) cinnamic acid), a naturally occurring phenolic acid in eelgrass (Zostera marina L.) plants, on spore adhesion and infection in two pathosystems: rice blast caused by Magnaporthe grisea and bean anthracnose caused by Colletotrichum lindemuthianum. We have shown that zosteric acid inhibits spore adhesion to model and host leaf surfaces and that any attached spores fail to develop appressoria, and consequently do not infect leaf cells. Low concentrations of zosteric acid that are effective in inhibiting adhesion are not toxic to either fungus or to the host. The inhibition of spore adhesion in the rice blast pathogen is fully reversible. On plants, zosteric acid reduced (rice) or delayed (bean) lesion development. These results suggest that there is potential for novel and environmentally benign crop protection technologies based on manipulating adhesion. 相似文献
3.
Kumiko Oka Akiko Okubo Motoichiro Kodama Hiroshi Otani 《Journal of General Plant Pathology》2006,72(3):152-158
In tomato plants, α-tomatine, a steroidal glycoalkaloid saponin, inhibits fungal growth. Tomato pathogens that produce host-specific
toxins, Alternaria alternata tomato pathotype causing Alternaria stem canker and Corynespora cassiicola causing Corynespora target spot, were investigated for sensitivity to α-tomatine. Although spore germination of A. alternata pathogenic and nonpathogenic to tomato and of C. cassiicola pathogenic to tomato was not affected by 0.1 mM α-tomatine, spore germination of C. cassiicola nonpathogenic to tomato was significantly inhibited. This result showed that A. alternata, regardless of its pathogenicity, and only the C. cassiicola pathogenic to tomato are resistant to α-tomatine. Germinating spores of A. alternata and C. cassiicola resistant to α-tomatine detoxified α-tomatine by degrading it to a less polar product. After inoculation of tomato leaves,
spores of A. alternata and C. cassiicola nonpathogenic to tomato germinated and formed appressoria, but did not form infection hyphae in host tissues. When a host-specific
toxin (CCT-toxin) produced by C. cassiicola pathogenic to tomato was added to nonpathogenic spores, colonization within leaves was observed in A. alternata, but not in C. cassiicola. On the other hand, when spores of C. cassiicola nonpathogenic to tomato were suspended in spore germination fluid of nonpathogenic A. alternata with α-tomatine detoxification activity, the fungus could be induced to colonize leaves in the presence of CCT-toxin. These
results indicate that A. alternata tomato pathotype and C. cassiicola pathogenic to tomato detoxify α-tomatine during infection and that this detoxification is essential for host colonization
by pathogens that produce host-specific toxins. 相似文献
4.
Cochliobolus miyabeanus forms a specialized infection structure, an appressorium, to infect rice. Contacting a hard surface induces appressorium
formation in C. miyabeanus, while the hydrophobicity of the substratum does not affect this morphogenic infection event. To determine whether the calcium/calmodulin-dependent
signaling system is involved in prepenetration morphogenesis in C. miyabeanus, the effects of a calcium chelator (ethylene glycol tetraacetic acid; EGTA), phospholipase C inhibitor (neomycin), intracellular
calcium channel blocker (TMB-8), calmodulin antagonists (chlorpromazine, phenoxybenzamine, and W-7), and calcineurin inhibitor
(cyclosporin A) on morphogenesis and infection were examined. Addition of Ca2+ and the calcium ionophore A23187 did not affect conidial germination, while the number of appressoria decreased with higher
concentrations. EGTA inhibited conidial germination and appressorium formation. The calcium channel blocker did not affect
appressorium formation at any concentration; however, calmodulin antagonists and the calcineurin inhibitor specifically reduced
appressorium formation at the micromolar level. One of the calmodulin antagonists, W-7, also inhibited accumulation of mRNA
of the calmodulin gene within germinating conidia and/or appressorium-forming germ tubes. Thus, biochemical processes controlled
by the calcium/calmodulin signaling system seem to be involved in the induction of prepenetration morphogenesis on rice. 相似文献
5.
The surface of the barley coleoptile is relatively hydrophobic. When the coleoptile surface was treated with water for 20 min, the contact angle of water droplets decreased and the surface became relatively hydrophilic. When conidia ofErysiphe graminis were inoculated on the hydrophobic surface of barley coleoptiles and immersed immediately in water, approximately 70% of the appressoria were normal after 24 h. In contrast, when conidia of E. graminis were inoculated on the hydrophilic surface of pre-wetted coleoptiles, only about 30% of the appressoria were normal. About 76% of the conidia that were strongly adherent developed normal appressoria. In contrast, only 20% of the conidia with weaker adherence developed normal appressoria. Application of a polycation(poly-
-ornithine: PLO) solution to the coleoptile surface prior to inoculation served to attach conidia to the surface of coleoptiles immersed in water. After PLO treatment, 70% of the conidia were strongly adherent. Furthermore, in water, 72% of the conidia developed normal appressoria on the surface of coleoptiles pretreated with PLO. These results suggest that normal appressorium development of E. graminis depends greatly on the intensity of adhesion of conidia to the substratum during the process of morphogenesis in water. 相似文献
6.
ABSTRACT Monilinia fructicola, which causes brown rot in stone fruit, forms appressoria on plant and artificial surfaces. On nectarine, the frequency of appressoria produced by conidial germlings depends to a large degree on the stage of fruit development, with numerous appressoria formed on immature (stage II) nectarine fruit, and no appressoria observed on fully mature fruit (late stage III). On polystyrene surfaces, appressorium formation was increased from <10% of germinated conidia to >95% of germinated conidia when the conidia were washed to remove residual nutrients and self-inhibitors. M. fructicola appressorium formation also appears to be regulated by the topography of the plant surface. On fruit, appressoria formed on stomatal guard cell lips, on the grooves of lateral cells adjacent to stomata or between two epidermal cells, and on the convex surfaces of epidermal cells. Pharmacological effectors indicate that cyclic AMP-, MAP kinase-, and calcium/calmodulin-dependent signaling pathways are involved in the induction and development of appressoria. KN-93, an inhibitor of calmodulin-dependent protein kinase II, did not inhibit conidial germination but did inhibit appressorium formation and brown rot development on flower petals, suggesting that appressoria are required for full symptom development on Prunus spp. petals. 相似文献
7.
ZJUF0986活性代谢产物对稻瘟病菌致病性的影响 总被引：2，自引：1，他引：1
通过菌丝生长速率法和悬滴法测定ZJUF0986活性代谢产物对稻瘟病菌菌丝生长、孢子萌发和附着胞形成的影响。结果表明,ZJUF0986活性代谢产物对稻瘟病菌菌丝生长的有效中浓度EC50为18.55mg/L,与对照药剂三环唑的EC50(17.30mg/L)相比无显著性差异。活性代谢产物不仅影响孢子萌发,也显著降低附着胞的形成。浓度为10mg/L的活性代谢物可完全抑制孢子萌发及附着胞的形成;浓度为1.25mg/L时则明显延缓孢子萌发及附着胞的形成,处理48h后的孢子萌发率和附着胞形成率分别为62.17%和38.46%。以浓度为1.25mg/L活性代谢产物处理的稻瘟病菌孢子悬浮液接种离体大麦叶片,病原菌孢子在大麦叶片表面能部分萌发形成附着胞,但侵染栓形成延迟,致病性明显降低。 相似文献
8.
Masaki Kanamori Ken-ichiro Saitoh Tsutomu Arie Takashi Kamakura Tohru Teraoka 《Journal of General Plant Pathology》2005,71(4):253-262
The rice blast fungus Magnaporthe grisea differentiates appressoria, which are required to attack its rice plant host. Clone A26, tentatively named LPL1, was previously found to be homologous to the known lysophospholipase genes from our subtractive cDNA library. The LPL1 protein had a consensus motif (GxSxG) and a catalytic triad (S, D, H) of esterases in the deduced amino acid sequence, and the protein expressed in Escherichia coli had lysophospholipase activity. To clarify the functions and possible roles of LPL1, the gene was disrupted by targeted gene replacement. The ΔLPL1 mutants formed fewer appressoria on the hydrophobic surface of GelBond film, and the appressoria had reduced turgor pressure and penetration into cells of the leaf sheath. The ΔLPL1 mutants and wild-type differentiated normal appressoria on other artificial substrata such as polycarbonate plate and on rice leaf sheath. Cytological analysis of the appressoria indicated that ΔLPL1 mutants had a delay in the disappearance of lipid droplets. These findings imply that LPL1, phospholipid metabolism, or both are involved in glycerol biosynthesis and accumulation to generate turgor pressure in the appressorium. LPL1 was, however, dispensable for full pathogenicity, suggesting that other complementary pathways or similar genes related to phospholipid metabolism probably function in M. grisea. 相似文献
9.
Y. Luo Z. Ma H. C. Reyes D. Morgan T. J. Michailides 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(2):145-154
The fungal pathogen Monilinia fructicola causes blossom blight and fruit brown rot of stone fruits in California. In this study, spore densities in the air were monitored
in six orchard/year combinations with Burkard spore traps. A real-time PCR assay was developed to efficiently quantify the
dynamics of spore density in these orchards during the growing season. Different patterns of dynamics of spore density were
observed in these orchards. A linear relationship between numbers of spores counted with a compound microscope and those determined
with the real-time PCR assay was obtained, using the same samples of spore traps. Spore density in five of six orchard/year
combinations ranged from 0.0 to 0.05 spores l−1, except for that in orchard 4, which showed much higher values of spore density in the air, as well as higher values and
wider range of incidences of blossom infection and fruit rot than those in the other orchards. The results demonstrated a
potential method to quantitatively determine spore inoculum potential in orchards by using a real-time PCR assay. 相似文献
10.
Kanako Inoue Tomoko Suzuki Kenichi Ikeda Shan Jiang Naoki Hosogi Gang-Su Hyong Sizuka Hida Taku Yamada Pyoyun Park 《Journal of General Plant Pathology》2007,73(6):388-398
Spores and infection structures such as germ tubes and appressoria of Magnaporthe oryzae, the fungus causing blast disease of wheat, produced an extracellular matrix (ECM) on the surfaces of host leaves during
fungal differentiation. The chemical components and function of the ECM were studied to understand the pathological roles
using two immunological techniques and ECM-digesting enzymes. The ECM was characterized by fibrous and amorphous materials,
located in the spaces between fungal cell walls and plant cuticles. Immunohistochemical and immunoelectron microscopy suggested
that ECM includes components positively reacted with antibodies of four animal cell adhesion factors (collagen VI, vitronectin,
fibronectin and laminin) and an animal integrin α3. ECM, incubated on a cellulose membrane, was rapidly digested by matrix
metalloproteinases (collagenase and gelatinase B), resulting in the detachment of most infection structures from membrane
surfaces. Both ultrastructural observation and immunological responses showed that more ECM was located at the appressoria
than at the spores and germ tubes. This result suggested that appressoria needed a powerful adhesion force for aggressive
action of penetration pegs into plant cuticles.
An erratum to this article can be found at 相似文献
11.
12.
Dale R. Walters 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(3):255-260
The ability of fungal pathogens to develop resistance to fungicides and to overcome genetic resistance in their hosts, coupled
with growing public concern for the environment, means that there is an urgent need for novel methods of disease control.
The leaf surface provides the first barrier that fungi must overcome in order to gain access to the leaf, but it also provides
chemical and physical cues that are necessary for the development of infection structures for many fungal pathogens. Film-forming
polymers can coat the leaf surface, acting not just as an extra barrier to infection, but also disguising the cues necessary
for germling development. Kaolin particle films can envelop the leaf in a hydrophobic particle film barrier that prevents
spores or water from directly contacting the leaf surface and as a result, can suppress infection. Adhesion of fungal spores
to the leaf surface, which is important to keep spores on the leaf surface and for appropriate development of the fungus on
the leaf surface, can be inhibited, leading to reduced infection and lesion development. Polymer and particle films have been
shown to provide disease control in the field, while research on agents that inhibit spore adhesion on leaf surfaces is still
in its infancy. There is an urgent need for research on the practicality of using these novel methods under field conditions
and on ways of integrating them into current crop protection programmes. 相似文献
13.
Yoshio Kurahashi Shinji Sakawa Haruhiko Sakuma Keiko Tanaka Gerd Haenssler Isamu Yamaguchi 《Pest management science》1999,55(1):31-37
Carpropamid (WIN™, KTU 3616) provides good control of leaf and panicle blast by ‘one-shot’ nursery-box treatment. It inhibits melanin biosynthesis in appressorial cells of Pyricularia oryzae, making them hyaline. Penetration by infection hyphae from the hyaline appressoria into rice epidermal cells is substantially hindered. In addition, the spread of rice blast spores from primary lesions to the other parts of the plant leading to secondary infection is largely prevented when the plants are treated with carpropamid by spray or water surface application. Secondary infection was simulated in a glass chamber fitted with an ultrasonic humidifier. On treated plants, many blast spores formed in the lesions, but the number of air spora that were dispersed from the lesions decreased significantly. A similar suppression of the spore liberation was observed in vitro when lesions on rice leaf segments, or discs from Pyricularia cultures on oatmeal agar were treated with the chemical. Spores from treated lesions or from the cultures on oatmeal agar amended with the chemical germinated normally and produced well-melanized appressoria on cellophane membranes. In addition, the spores proved to be fully pathogenic towards rice seedlings, producing normal disease symptoms. These results strongly suggest that carpropamid reduces the secondary infection of rice by Pyricularia by specifically hindering spore liberation. © 1999 Society of Chemical Industry 相似文献
14.
为明确绿僵菌在其致死害虫表面生长发育和致病力等相关分子机制,通过显微观察大蜡螟Galleria mellonella虫尸表面罗伯茨绿僵菌Metarhizium robertsii生长和产孢特性,并测定其致病力,分别对虫尸表面和PDA培养基上罗伯茨绿僵菌的菌丝生长阶段和大量产孢阶段进行高通量测序,对虫尸表面罗伯茨绿僵菌产孢及致病力通路相关基因进行系统分析,并采用荧光定量PCR技术对高通量测序结果进行验证。结果表明,PDA培养基上培养5 d后,罗伯茨绿僵菌开始大量产孢,培养14 d时产孢量最高,为4.6×10~7个/cm~2,大蜡螟幼虫注射罗伯茨绿僵菌4 d后,其体表出现菌丝,5.5 d后虫尸表面罗伯茨绿僵菌大量产孢,9 d后产孢量最高,为2.6×10~8个/cm~2。与PDA培养基上罗伯茨绿僵菌对大蜡螟幼虫的半致死时间(7.09 d和4.66 d)相比,体壁侵染法和显微注射法侵染的虫尸表面罗伯茨绿僵菌对大蜡螟幼虫的半致死时间(6.33 d和4.49 d)分别显著缩短和无显著变化。高通量测序结果显示,在菌丝生长阶段和大量产孢时期,虫尸表面罗伯茨绿僵菌中共有810个基因上调表达,452个基因... 相似文献
15.
R. E. Niks 《European journal of plant pathology / European Foundation for Plant Pathology》1981,87(5):201-207
One of the components of partial resistance of barley to leaf rust,Puccinia hordei, is a reduced infectibility. It was investigated whether this low infectibility may rest on a hampered appressorium formation of the leaf rust fungus. The appressorium formation on the primary leaves of 11 barley genotypes with an intermediate-to-low infectibility was compared with that on the highly infectible L94. The number of stomata per cm2 leaf area occupied by appressoria ofP. hordei was determined per genotype by means of fluorescence microscopy. No cosistent differences could be detected, indicating that the mechanisms causing a low infectibility of partially resistant barley seedlings act at a phase later than the formation of the appressoria. On the non-host wheat not fewer appressoria were formed than on L94, but no appressoria were found on a lettuce genotype. The latter probably lacks the stimuli that enable the fungus to find stomata.Samenvatting Eén van de componenten van partiële resistentie van gerst tegen dwergroest,Puccinia hordei, is een verminderde infectiedichtheid. Het mechanisme, dat hieraan ten grondslag ligt, is onbekend. Een experiment werd uitgevoerd om na te gaan of bij partieel resistente rassen een verminderde appressoriumvorming optreedt. Na inoculatie in een inoculatietoren en een zorgvuldig uitgevoerde incubatie werd het aantal huidmondjes per cm2 bladoppervlak bepaald dat bezet was door appressoria vanP. hordei. De elf weinig vatbare gerstlijnen uit deze studie bleken niet reproduceerbaar te verschillen van de zeer vatbare gerstlijn L94 in de mate van appressoriumbezetting. Dit wijst erop dat infectiedichtheidsverschillen t.g.v. partiële resistentie veroorzaakt worden door mechanismen die werken na de appressoriumvorming. In een tweede experiment werd aangetoond dat zelfs op de niet-waardsoort tarwe, waaropP. hordei geen symptomen veroorzaakt, niet minder appressoria worden gevormd dan op L94. Op een sla-genotype trad echter geen appressoriumvorming op. Op deze laatste niet-waardsoort ontbreken waarschijnlijk de stimuli die de schimmel in staat stellen huidmondjes te vinden. 相似文献
16.
Adhesion to the host surface is the first step for successful plant pathogen development and has been reported to be associated with both passive and active processes. For conidia of Venturia inaequalis, which depend on leaf wetness for germination, this process has not yet been described. Conidia of V. inaequalis adhered to wet hydrophobic surfaces immediately after contact to the surface, hours before initiation of germination. Attachment of nongerminated conidia was much better on hydrophobic surfaces, such as apple leaves and polystyrene, than on hydrophilic glass. Conidia released adhesive material localized in a droplet named spore tip glue (STG) at the spore apex which interacted with a contact surface only when water was present. Histochemical investigations indicated the presence of proteins and carbohydrates in STG, lectin labeling the presence of beta-galactose and N-acetylglucosaminyl residues. Transmission electron microscopy revealed two phases in the STG at the tip of dry mature conidia; as STG was present on the outer side of the intact fungal cell wall its formation should be associated with the secretion of glue through pores of the conidial wall. Surface-active substances affected the adhesion of conidia to hydrophobic surfaces stressing the importance of hydrophobic interactions. The use of protein biosynthesis inhibitors did not affect adhesion of conidia indicating that the adhesive material was preformed. It is concluded that the coincidence of STG, contact to a hydrophobic surface, and free water are essential for the adhesion of V. inaequalis conidia. 相似文献
17.
Tony J. Collins Bruno M. Moerschbacher Nick D. Read 《Physiological and Molecular Plant Pathology》2001,58(6):259
The leaf alcohols cis -3-hexen-1-ol and trans -2-hexen-1-ol have been previously shown to induce the wheat stem rust (Puccinia graminis f. sp. tritici) to differentiate appressoria in a complex axenic culture medium. In this paper, the possible role of these chemicals in appressorium induction during infection has been analysed further. The inductive potential of ethylene and three cutin monomers were also tested because they have been found to induce appressoria in other fungi. Both hexenols were found to be inductive in aqueous solution in the absence of media constituents. 0.5–1 m
trans -2-hexen-1-ol was the most inductive resulting in a maximum of 51% appressorium differentiation. trans -2-hexen-1-ol was also shown to be inductive in vapour form. In aqueous solution, trans -2-hexen-1-ol acted synergistically with topographical signals by increasing the rate of appressorium induction. Combining the two signals also increased the total number of appressoria differentiated (88%). The other chemicals tested were non-inductive although a biochemical domain rich in exposed cutin was localized around stomatal apertures of wheat leaves. The characteristic bipolar morphology of appressoria formed over stomata was found to be determined by topographical signals. Overall, our data support a role for both chemical signals (hexenols or their analogues) and topographical signals being involved in appressorium induction by wheat stem rust. 相似文献
18.
Fungi were screened for the production of inhibitors of appressorium formation in germinating conidiospores of Magnaporthe grisea on inductive and non-inductive surfaces. Bioactivity-guided isolation yielded glisoprenins A, C, D and E from Gliocladium roseum and oleic acid from three fungi. The glisoprenins were active only on a hydrophobic surface, whereas oleic acid inhibited appressorium formation on a hydrophilic surface when 1,16-hexadecanediol, but not 8-(4-chlorophenylthio)adenosine-3′,5′-monophosphate, was used as inducer. The inhibition by glisoprenins could be reversed competitively by 1,2-dioctanoylglycerol but not by 1-oleoyl-2-acetyl-glycerol, both effective activators of protein kinase C in mammalian cells. Other mono-unsaturated fatty acids also inhibited appressorium formation. The corresponding methyl esters were inactive. The results agree with previous findings that at least two signal-transducing pathways are involved in appressorium formation. In addition, the differences observed between fungal signalling via PKC and the pathway used in mammalian cells could be used for the search for new and selective fungicides for rice blast disease. © 1998 Society of Chemical Industry 相似文献
19.
A resistant type of small, spheroid clubroot galls (SSGs) containing resting spores formed on the root surface of clubroot-resistant
(CR) cultivars of Chinese cabbage (Brassica
rapa L. subsp. pekinensis) inoculated with an avirulent population of Plasmodiophora
brassicae. Populations isolated from the SSGs severely affected a common (susceptible) cultivar but did not have the typical pathogenicity
on CR cultivars, indicating similarity in pathogenicity between SSG and original spore populaions. Populations pathogenic
on CR cultivars were not detected from SSGs. Therefore, the ability of the avirulent population among the SSGs to form resting
spores may need to be considered to achieve clubroot control in common cultivars of crucifers. 相似文献
20.
ABSTRACT An infection-inhibiting factor (IIF) was isolated from strawberry leaves and identified as (+)-catechin. This compound inhibited the formation of infection hyphae from appressoria of Alternaria alternata, but allowed both spore germination and appressorial formation. It is a normal component of strawberry leaves, but further accumulates as the major IIF in response to inoculation with nonpathogenic spores of A. alternata. The accumulation of (+)-catechin on a susceptible host was not induced, however, by inoculation with pathogenic spores of the strawberry pathotype or by inoculation with nonpathogenic spores supplemented with host-specific toxin (AF-toxin I). These results imply that (+)-catechin acts as a protective agent during induced resistance and that AF-toxin I acts as a fungal suppressor of induced resistance. 相似文献