Ultrastructure of the vascular responses of tobacco to Fusarium oxysporum f.sp. nicotianae

1996 ◽  
Vol 74 (8) ◽  
pp. 1273-1278 ◽  
Author(s):  
W. C. Mueller ◽  
A. T. Morgham

The reactions of a broadleaf tobacco variety polygenically resistant to Fusarium wilt were compared with a susceptible variety. Symptoms of wilting, yellowing, and eventual death of leaves in the susceptible variety were associated with rapid movement of the fungus through the plant, whereas in the resistant variety the fungus was confined to the lower portion of the plant and symptoms occurred only on the lowermost leaves. The responses in the vascular tissue were similar in both varieties but appeared more intense in the resistant variety. Lipoidal wall coatings and occlusions occurred in the initially infected vessels. Apposition layers containing callose were deposited in the contact cells within 1 day of inoculation. Lipoidal occlusions occurred in the secondarily infected vessels, but apposition layers were not detected in the contact cells. Tyloses were not observed. Resistance is associated with the localization and slower movement of the fungus that is reflected in the observable differences in symptom development. Keywords: contact cells, Nicotiana tabacum, polygenic resistance, vascular occlusion.

Author(s):  
K. P. Suthar ◽  
R. M. Patel ◽  
D. Singh

Chickpea (Cicer arietinum L.) is pivotal source of protein for vegetarian diet, however, its productivity is adversely affected by wilt disease. Non pathogenic rhizospheric microorganism’s leads to induce resistance and are found to be effective in management of this disease. The polyamines (PAs) content and its metabolism are the key in plant microbial interaction, so the alteration in PAs viz. spermidine (SPD), spermine (SPM) and putresine (PTR) in chickpea by Bacillus substilis isolate K18 (BS-K18) effective antagonist (75%) of Fusarium oxysporum f. sp. ciceri (Foc) and having PGPR traits was analyzed under Foc stress. The higher PAs content was reported in resistant variety (WR-315) compared to susceptible variety (JG-62). The PTR was dominant PA present in chickpea, further overall root tissue reported higher PA content as compared to leaves tissue. The PA content was constitutively improved by B. subtilis seed treatment in resistant and susceptible varieties. The Foc stress leads to induction of PA content in leaves and root tissue, where its content was higher in resistant variety as compared to susceptible variety. The BS-K18 seed treatment under Foc stress leads to induction of PA content as compared to both treatments alone, the SPD and SPM were more induced in leaves and root tissue of susceptible variety whereas PTR was more induces in resistant variety. Overall, polyamines were induced up to 3 DAT then after decline suggest their early role in plant defence mechanism, further PTR was found to be dominating polyamine during chickpea-Foc interaction under BS-K18 treatment. The Bacillus subtilis seed treatment leads to improve wilt tolerance in susceptible var. JG-62 through modulation of PAs, the same mechanism also helped to enhanced effectiveness of resistant var. WR-315.


1961 ◽  
Vol 39 (1) ◽  
pp. 7-19 ◽  
Author(s):  
A. G. Lochhead ◽  
F. D. Cook

A comparison was made of growth factor requirements and growth factor synthesizing capacity of bacteria from the root surface and from the seeds of flax varieties resistant and susceptible, respectively, to wilt caused by Fusarium oxysporum f. lini. The percentage of bacteria from both root and seed which required growth-promoting substances was greater with the resistant ('Bison') than with the susceptible ('Novelty') variety. On the other hand bacteria capable of synthesizing growth factors were proportionately more abundant with the susceptible variety. The findings indicate a more pronounced rhizosphere effect exerted by the susceptible than by the resistant variety, and point to circumstances that favor a greater accumulation (or 'turnover') of vitamins and related substances at the root surface of susceptible plants.Two strains of Fusarium oxysporum f. lini capable of inducing wilt required no vitamins for growth; thiamine had a depressing effect. Both strains were able to synthesize various growth factors, though in different degree. Culture filtrates of bacteria from roots of the two varieties of flax showed no difference in their effect on growth of Fusarium; however, bacteria from the resistant variety showed somewhat greater ability to depress Fusarium than those from the susceptible. Though the findings do not constitute evidence of any relationship between differences in growth factor relationships to pathogenic potential of Fusarium, they suggest the value of considering growth-promoting substances in studies of the effect of nutrition on the activity of soil-borne pathogens.


1967 ◽  
Vol 13 (2) ◽  
pp. 199-203 ◽  
Author(s):  
E. A. Peterson ◽  
J. W. Rouatt

The root microflora of Bison flax, resistant to wilt caused by Fusarium oxysporum f. lini, was compared with that of the wilt-susceptible variety Novelty. Plants grown in "disease-free" soil show that the susceptible variety harbors not only the most numerous, but also the most metabolically active bacterial flora on its roots. Generic classification of bacterial isolates shows a higher incidence of more active organisms, represented by Pseudomonas and Flavobacterium on roots of the susceptible crop, whereas the more slowly growing pleomorphic types such as Arthrobacter were most abundant on roots of the resistant variety. Fungi were also more numerous on roots of the susceptible crop, but the generic composition of rhizosphere populations of both varieties was similar to that of the soil itself. Fusarium oxysporum dominated the flora occurring in an active mycelial state on roots of the susceptible variety, whereas F. oxysporum and Phoma sp. were codominants in the active flora of the resistant crop. Tests with other soils showed that dominance of specific genera varies with soil type. The results indicate a selective action on the root microflora, particularly the bacteria, and suggest both quantitative and qualitative differences in root environments of the two flax varieties.


2017 ◽  
Vol 40 (04) ◽  
Author(s):  
Y. M. Shukla ◽  
K. P. Suthar

Alterations in b-1,3 glucanase and chitinase activity during host-pathogen interaction were studied in chickpea varieties JCP 27 (resistant) and JG 62 (susceptible) to vascular wilt caused by Fusarium oxysporum f. sp. ciceri race 4. The enzyme activities were analyzed in root, stem and leaf tissues at three stages viz., pre-infection, infection and post-infection in normal and inoculated soil. The b-1,3 glucanase activity in root, stem and leaf tissues of susceptible variety found higher than those of resistant one at all the stages of infection under inoculated condition.. The chitinase activity in root and leaf tissues of susceptible variety was higher than the resistant variety at all infection stages in inoculated soil, whereas in stem tissue the activity level was higher in resistant variety at pre-infection and infection stages. Overall result revealed that b-1,3 glucanase showed higher induction with increase in inoculums pressure of the fungal pathogen, whereas hydrolytic enzyme chitinase was induced only when inoculum pressure of the fungal pathogen was severe.


1994 ◽  
Vol 72 (4) ◽  
pp. 505-509 ◽  
Author(s):  
W. C. Mueller ◽  
A. T. Morgham ◽  
E. M. Roberts

Callose (β-1,3-glucan) was localized with the electron microscope in the contact cells surrounding vessels of tomato and cotton infected with Fusarium oxysporum by means of gold labelling with a polyclonal antiserum to β-1,3-glucan. The callose was deposited in the apposition layers formed after infection in the cells surrounding initially infected vessels. Callose was not detected in the contact cells surrounding secondarily infected vessels. Callose could be detected in the contact cells of resistant and susceptible tomato cultivars 4 h after inoculation. Key words: β-1,3-glucans, contact cells, gold labelling, Gossypium, Lycopersicon esculentum.


2018 ◽  
Vol 24 (1) ◽  
pp. 43
Author(s):  
Syahrir Pakki ◽  
Mappaganggang Mappaganggang

<p>Two experiments to study responses of resistance of maize germplasm to downy mildew (Peronosclerospora philipinensis) have been conducted. Both experiments were arranged in randomized block design with two replication. The treatments in each experiment (2014 and 2016) were 70 maize accessions. The accessions were planted in planting distant of 75 cm × 20 cm, in 5 m rows, resulting in 20 plants per row. In every 10 rows, two check varieties were planted, i.e. one susceptible and one resistant variety. Ten days prior to planting, the soil was fertilized with mixed fertilizers consisted of urea, ZA, SP36, and KCl at a dose of 100, 100, 100, and 100 kg/ha, respectively. Fertilization II and III was given at 30 days after planting, and 45 days after planting with a dose of 100 kg urea/ha. As a source of inoculum downy mildew, around the repeated plot was planted with varieties Anoman variety (susceptible variety) that was inoculated with a suspension of downy mildew pathogen. Observation was conducted at 25, 35, and 55 days after planting, with the standard score of resistant to downy mildew, followed: 0–10% = resistant, 11–25% = moderately resistant, 26–50% = moderately susceptible, &gt;50% = susceptible. The result of the experiments showed that there were 5 accessions resistant to downy mildew (P. philipinensis), i.e. CML 440×MR4-9-30-3, 664, 60, 572, and 554 with the intensity of downy mildew infection ranged from 5 to 10%. Twelve other accessions were classified as moderately resistant, i.e. CML 440×MR4-9-98-2, 440×MR4-9-98-4 CML, CML 440×MR4-9-124-1, 66, 71, 319, 108, 73, 48, 105, 554, and 682 with intensity of infection ranged from 13 to 25%. At the same experiments, the average intensity of downy mildew infection on susceptible check varieties reached 100 percent.</p>


2020 ◽  
Vol 6 (2) ◽  
pp. 29
Author(s):  
GEMBONG DALMADIYO ◽  
CECE SUHARA ◽  
SUPRIYONO SUPRIYONO ◽  
SUDJINDRO SUDJINDRO

<p><strong>Evaluation on the resistance of kenaf accessions (Hibis¬ cus cannabinus /..) to Fusarium oxysporum Schlect</strong></p><p>Resistant variety is one of the most important components controlling of fusarium wilt disease on kenaf caused by Fusarium oxysporum Schlect. To ind out resistant variety an evaluation on kenaf accessions was conducted in the laboratory and screen house of Phytopathology, RITFC, Malang in June-December 1997. The results of the selection on 77 accessions showed that 41 accessions were highly resistant, 1 2 accessions were resistant, 7 accessions were moderate, 12 accessions were susceptible, and 5 accessions were highly susceptible Three resistant and highly resistant accessions were namely 85-9-73, DS/005 H, and FJ/004 He could inhibit F. oxysporum growth about 23.40- 32.43 mm and its discolorisation about 0.0-13.4%.</p>


2020 ◽  
Author(s):  
Yuexin Li ◽  
Degang Zhao

Abstract Background: Late blight seriously threatens potato cultivation worldwide. The severe and widespread damage caused by the fungal pathogen can lead to drastic decreases in potato yield. Although grafting technology has been widely used to improve crop resistance, the effects of grafting on potato late blight resistance as well as the associated molecular mechanisms remain unclear. Therefore, we performed RNA transcriptome sequencing analysis and the late blight resistance testing of the scion when the potato late blight-resistant variety Qingshu 9 and the susceptible variety Favorita were used as the rootstock and scion, respectively, and vice versa. The objective of this study was to evaluate the influence of the rootstock on scion disease resistance and to clarify the related molecular mechanisms.Results: A Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that the expression levels of genes related to plant–pathogen interactions, plant mitogen-activated protein kinase (MAPK) signaling pathways, and plant hormone signal transduction pathways were significantly up-regulated in the scion when Qingshu 9 was used as the rootstock. These genes included late blight response genes encoding calcium-dependent protein kinases (CDPKs), chitin elicitor receptor kinases (CERKs), LRR receptor serine/threonine protein kinases (LRR-LRKs), NPR family proteins in the salicylic acid synthesis pathway, and MAPKs. When Favorita was used as the rootstock, the expression levels of the late blight response genes were not up-regulated in the Qingshu 9 scion, but the expression levels of the genes related to proline metabolism, fatty acid chain elongation, and diterpenoid biosynthesis pathways were down-regulated. Resistance results showed that self-grafting of the susceptible variety and grafting with the resistant variety as the rootstock increased the resistance of the susceptible scion to late blight. However, the resistance was stronger after grafting with the resistant variety as the rootstock. Using the susceptible variety as the rootstock decreased the late blight resistance of the resistant scion.Conclusions: Our results showed that changes to the expression of disease resistance genes in the scion after grafting are associated with late blight resistance. The results provide the basis for exploring the molecular mechanism underlying the effects of rootstocks on scion disease resistance.


Pathogens ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 112 ◽  
Author(s):  
Spanic ◽  
Horvat ◽  
Drezner ◽  
Zdunic

The grain yield, as well as the quality and safety of the wheat grains and corresponding malt can be compromised by Fusarium spp. infection. The protein content of the grain affects the chemical composition and enzyme levels of the finished malt. The malting industry demands varieties with good malting and brewing performance, as well as good agronomic performance and disease resistance. The best method of disease control is breeding and selection for resistant varieties. Due to higher requirements for malting wheat worldwide, the goal of this investigation was to explore changes in protein distribution in wheat grains and corresponding malt, which are under higher pressure of Fusarium head blight (FHB) infestation in field conditions. The present study provides new knowledge on the impact of the FHB on the distribution of protein components of naturally Fusarium-infected (control) and Fusarium-inoculated wheat varieties in the grain and the corresponding malt in two consecutive years (2015/2016 and 2016/2017). The results showed that Fusarium infection of the susceptible variety Golubica, decreased total glutenins (5.9%), and both high and low molecular weight glutenin subunits (2.5% and 3.5%, respectively) in wheat grains, compared to control, in 2016. In contrast, gliadins and α-gliadins increased significantly (+7.6% and +5.1%, respectively) in the same variety. Wheat grains of the more resistant variety Vulkan showed an increase of the total glutenins content (+4.3%), and of high and of low molecular weight glutenin subunits (+1.2% and +3.2%, respectively) after Fusarium-inoculation, compared to naturally infected grains in 2016. Susceptible variety Golubica increased total glutenins (+9.1%), and both high and low molecular weight glutenin subunits (+3.5% and +5.6%, respectively) after Fusarium-inoculation in wheat malt, compared to naturally infected malt in 2016. In 2017, when disease pressure was higher than in 2016, there was a tendency in all varieties to increase gliadins and its sub fractions after malting, and to decrease glutenins and its sub fractions in Fusarium-inoculated treatment. In conclusion, FHB dramatically depressed grain yield (up to 37%) and quality (glutenins and high molecular weight subunits) in the susceptible Fusarium variety, which makes it inconvenient for malting.


2017 ◽  
Vol 5 (4) ◽  
pp. 123 ◽  
Author(s):  
Asma Akbar ◽  
Gul Shad Ali ◽  
Brian Pearson ◽  
Farrukh Hamid ◽  
Sonia Sumreen

Grey blight is a foliar disease of tea plants (Camellia sinensis) caused by Pestalotiopsis. The grey blight pathogen was isolated from infected leaves of tea plants in the National Tea and High Value Crop Research Institute (NTHRI), Shinkiari, Khyber Pakhtunkhwa, Pakistan. Eight different varieties, Indonesian, Roupi, Jue King, P-5, P-3, Qi man, Chuy and P-1, were investigated for yield loss and resistance against the grey blight disease. All varieties displayed considerably different levels of resistance to Pestalotiopsis (p<0.05). The most resistant variety was Indonesian, which showed the lowest number of lesions (1.5 leaf-1) and the smallest lesion diameter (3.0 cm), whereas the most susceptible variety was P-1 which showed the highest number of lesions (3.83 leaf-1) and the largest lesion diameter (15.0 cm). The grey leaf blight pathogen significantly affected biomass and dry matter of the tested varieties. Compared to non-inoculated control, inoculation with Pestalotiopsis reduced the number of leaves by 40% (p<0.05), fresh leaf weight by 31% (p<0.05) and dry leaf weight by 59% (p<0.05). Whereas, the Indonesian variety was the least affected showing only 11% (p<0.05), 19% (p<0.05), and 28% (p<0.05) reduction in number of leaves, fresh weight and dry weight, respectively, over control. These results showed that Pestalotiopsis significantly reduced tea yield and that this disease can be managed by growing resistant varieties.


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