Disruption of ultrastructure and cytoskeletal network is involved with biocontrol of damping-off pathogen Aphanomyces cochlioides by Lysobacter sp. strain SB-K88

2008 ◽  
Vol 46 (3) ◽  
pp. 312-321 ◽  
Author(s):  
Md. Tofazzal Islam
Keyword(s):  
Damping Off ◽  
Aphanomyces Cochlioides ◽  
Cytoskeletal Network

scholarly journals Mycofumigation with Muscodor albus and Muscodor roseus for Control of Seedling Diseases of Sugar Beet and Verticillium Wilt of Eggplant

Plant Disease ◽  
2003 ◽  
Vol 87 (11) ◽  
pp. 1349-1354 ◽  
Author(s):  
A. M. Stinson ◽  
N. K. Zidack ◽  
G. A. Strobel ◽  
B. J. Jacobsen
Keyword(s):  
Sugar Beet ◽  
Solanum Melongena ◽  
Pythium Ultimum ◽  
Potato Dextrose Agar ◽  
Infested Soil ◽  
Damping Off ◽  
Stand Establishment ◽  
Aphanomyces Cochlioides ◽  
Alginate Capsules ◽  
Antimicrobial Volatiles

Mycofumigation is the use of antimicrobial volatiles produced by fungi such as Muscodor albusitalic and M. roseus for the control of other organisms. Sugar beet (Beta vulgaris L.) stand establishment was increased and disease severity decreased by mycofumigation with M. roseus and M. albus in autoclaved soil infested with Rhizoctonia solani, Pythium ultimum, or Aphanomyces cochlioides. Eggplant seedlings (Solanum melongena L.) transplanted into autoclaved soil infested with Verticillium dahliae and mycofumigated with M. albus and M. roseus had significantly less disease (P < 0.05) after 4 and 5 weeks compared with nonmycofumigated Verticillium-infested soil. The effect of formulation on efficacy of mycofumigation with M. roseus was tested using potato dextrose agar strips, alginate capsules, ground barley, pesta granules, and stabileze granules. The stabileze and ground barley formulations of M. roseus resulted in the best control of P. ultimum damping-off. The best control of A. cochlioides damping-off was with the stabileze formulation, and the stabileze, ground barley, and agar strip formulations provided similar control of R. solani damping-off. In soil infested with P. ultimum, mycofumigation with M. albus stabileze formulation resulted in stand establishment similar to that in the autoclaved soil. Mycofumigation was ineffective in controlling Fusarium wilt of sugar beet. Neither M. albus nor M. roseus affected sugar beet or eggplant growth or appearance except in the stabileze formulation, where stunting was noticed. Mycofumigation with M. albus and M. roseus shows promise for control of soilborne diseases caused by P. ultimum, A. cochlioides, R. solani, and V. dahliae.

Secondary Metabolites from Nonhost Plants Affect the Motility and Viability of Phytopathogenic Aphanomyces cochlioides Zoospores

2008 ◽  
Vol 63 (3-4) ◽  
pp. 233-240 ◽  
Author(s):  
Tofazzal Islam
Keyword(s):  
Secondary Metabolites ◽  
Potential Role ◽  
Cumulative Effect ◽  
Repellent Activity ◽  
Damping Off ◽  
Aphanomyces Cochlioides ◽  
Dalbergia Odorifera ◽  
Acetone Extracts ◽  
Chinese Medicinal Plant

The motile zoospores of the damping-off pathogen Aphanomyces cochlioides aggregate on host plants (e. g., sugar beet, spinach) guided by the host-specific plant signal cochliophilin A before infection. To assess the potential role of secondary metabolites in nonhost resistance, acetone extracts of 200 nonhost traditional medicinal plants from Chinese and Bangladeshi origins were tested for the motility behaviour of A. cochlioides zoospores using a particle bioassay method. Nearly one third of the tested plant extracts exhibited diverse deleterious activities such as repellent, stimulant, motility halting and lysis against A. cochlioides zoospores. Among these active plants, an extract of the Chinese medicinal plant Dalbergia odorifera displayed potent repellent activity toward zoospores. Chromatographic separation of D. odorifera constituents revealed that the repellent activity was regulated by the cumulative effect of three motility-affecting isoflavonoids, viz. (±)-medicarpin (repellent at 150 μg/ml), (-)-claussequinone (stimulant at 100 μg/ml) and formononetin (stimulant and attractant at 50 μg/ml). A mixture (1:1:1, w/w/w) of these three compounds exhibited only repellent activity toward zoospores at a concentration lower than 50 μg/ml. These results suggest that nonhost plants might possess potential bioactive secondary metabolites to ward off zoosporic phytopathogens

scholarly journals Suppression of Damping-Off Disease in Host Plants by the Rhizoplane Bacterium Lysobacter sp. Strain SB-K88 Is Linked to Plant Colonization and Antibiosis against Soilborne Peronosporomycetes

2005 ◽  
Vol 71 (7) ◽  
pp. 3786-3796 ◽  
Author(s):  
Md. Tofazzal Islam ◽  
Yasuyuki Hashidoko ◽  
Abhinandan Deora ◽  
Toshiaki Ito ◽  
Satoshi Tahara
Keyword(s):  
Sugar Beet ◽  
Microscopic Analysis ◽  
Inhibitory Effect ◽  
Root Surface ◽  
Plant Colonization ◽  
Damping Off ◽  
Electron Microscopic ◽  
Aphanomyces Cochlioides ◽  
Direct Inhibitory Effect ◽  
A Cell

ABSTRACT We previously demonstrated that xanthobaccin A from the rhizoplane bacterium Lysobacter sp. strain SB-K88 suppresses damping-off disease caused by Pythium sp. in sugar beet. In this study we focused on modes of Lysobacter sp. strain SB-K88 root colonization and antibiosis of the bacterium against Aphanomyces cochlioides, a pathogen of damping-off disease. Scanning electron microscopic analysis of 2-week-old sugar beet seedlings from seeds previously inoculated with SB-K88 revealed dense colonization on the root surfaces and a characteristic perpendicular pattern of Lysobacter colonization possibly generated via development of polar, brush-like fimbriae. In colonized regions a semitransparent film apparently enveloping the root and microcolonies were observed on the root surface. This Lysobacter strain also efficiently colonized the roots of several plants, including spinach, tomato, Arabidopsis thaliana, and Amaranthus gangeticus. Plants grown from both sugar beet and spinach seeds that were previously treated with Lysobacter sp. strain SB-K88 displayed significant resistance to the damping-off disease triggered by A. cochlioides. Interestingly, zoospores of A. cochlioides became immotile within 1 min after exposure to a SB-K88 cell suspension, a cell-free supernatant of SB-K88, or pure xanthobaccin A (MIC, 0.01 μg/ml). In all cases, lysis followed within 30 min in the presence of the inhibiting factor(s). Our data indicate that Lysobacter sp. strain SB-K88 has a direct inhibitory effect on A. cochlioides, suppressing damping-off disease. Furthermore, this inhibitory effect of Lysobacter sp. strain SB-K88 is likely due to a combination of antibiosis and characteristic biofilm formation at the rhizoplane of the host plant.

3-D examination of the cytoskeletal sheets of mammalian eggs

1992 ◽  
Vol 50 (1) ◽  
pp. 914-915
Author(s):  
Carolyn A. Larabell ◽  
David G. Capco ◽  
G. Ian Gallicano ◽  
Robert W. McGaughey ◽  
Karsten Dierksen ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Somatic Cells ◽  
Freeze Fracture ◽  
Blastocyst Stage ◽  
Cell Cytoplasm ◽  
Planar Structures ◽  
Cytoskeletal Network ◽  
Entire Cell ◽  
Cytoskeletal Networks ◽  
Mammalian Eggs

Mammalian eggs and embryos contain an elaborate cytoskeletal network of “sheets” which are distributed throughout the entire cell cytoplasm. Cytoskeletal sheets are long, planar structures unlike the cytoskeletal networks typical of somatic cells (actin filaments, microtubules, and intermediate filaments), which are filamentous. These sheets are not found in mammalian somatic cells nor are they found in nonmammalian eggs or embryos. Evidence that they are, indeed, cytoskeletal in nature is derived from studies demonstrating that 1) the sheets are retained in the detergent-resistant cytoskeleton fraction; 2) there are no associated membranes (determined by freeze-fracture); and 3) the sheets dissociate into filaments at the blastocyst stage of embryogenesis. Embedment-free sections of hamster eggs viewed at 60 kV show sheets running across the egg cytoplasm (Fig. 1). Although this approach provides excellent global views of the sheets and their reorganization during development, the mechanism of image formation for embedment-free sections does not permit evaluation of the sheets at high resolution.

Damping-off of sugar beet in Finland: II. Disease control 

1983 ◽  
Vol 55 (5) ◽  
pp. 431-450
Author(s):  
Mauritz Vestberg ◽  
Risto Tahvonen ◽  
Kyösti Raininko
Keyword(s):  
Sugar Beet ◽  
Disease Control ◽  
Field Experiments ◽  
Damping Off ◽  
Good Protection ◽  
Great Damage

In pot and field experiments carried out in 1979-1981, the systemic funqicide hymexazol prevented satisfactorily soil borne damping-off of sugar beet caused mainly by the fungus Pythium debaryanum auct. non Hesse. The results with the combination hymexazol + thiram were still better. This treatment gave very good protection against the disease up to about two to three weeks after emergence, increased the yield on the average by 5-10 % and produced considerably thicker and denser stands. Thereafter a large number of beets may have become infected, but no great damage was caused as only few died. Band spraying at emergence using hymexazol with a large amount of water as well as spraying into the seed furrow prevented the outbreak of the disease almost completely. Liming had little effect on damping-off.

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