Potential for biological control of Cercosporidium personatum leafspot of peanuts by Dicyma pulvinata

1987 ◽  
Vol 65 (11) ◽  
pp. 2263-2269 ◽  
Author(s):  
James K. Mitchell ◽  
Donald H. Smith ◽  
Ruth A. Taber
Keyword(s):  
Biological Control ◽  
Environmental Conditions ◽  
Field Conditions ◽  
Leaf Wetness ◽  
Wild Type ◽  
Cercosporidium Personatum ◽  
Type Isolate ◽  
65 H

The biology of Dicyma pulvinata (Berk. & Curt.) v. Arx, a mycoparasite of Cercosporidium personatum (Berk. & Curt.) Deighton, was investigated under both laboratory and field conditions. At 26 °C, conidia of D. pulvinata close to both hyphae and conidia of C. personatum germinated within 11–17 h. Visible signs of colonization of lesions of C. personatum by D. pulvinata appeared within 58–65 h (21–31.5 h leaf wetness). Dicyma pulvinata was an effective protectant when plants were exposed to continuous leaf wetness at 26 °C for 5 days. In field microplot studies, lesions of C. personatum were visibly colonized by both mutant and wild-type isolates of D. pulvinata within 4 days after applying their conidial suspensions. Environmental conditions during this 4-day period were 40 h leaf wetness, 60 h of 23–28 °C (optimal temperatures for growth of the wild-type isolate), and 17.31 cm rainfall.

scholarly journals Isolation of Nonpathogenic Mutants of Fusarium oxysporum f. sp. melonis for Biological Control of Fusarium Wilt in Cucurbits

2002 ◽  
Vol 92 (2) ◽  
pp. 164-168 ◽  
Author(s):  
Stanley Freeman ◽  
Aida Zveibil ◽  
Haim Vintal ◽  
Marcel Maymon
Keyword(s):  
Biological Control ◽  
Fusarium Oxysporum ◽  
Fungal Pathogens ◽  
Conidial Suspension ◽  
Wild Type ◽  
Seedling Mortality ◽  
Type Isolate ◽  
Novel Approach ◽  
Mutant Strains ◽  
Race 2

Two nonpathogenic mutant strains 4/4 and 15/15 of Fusarium oxysporum f. sp. melonis (race 1,2) were isolated by a continuous dipinoculation technique following UV mutagenesis of the virulent wild-type isolate FOM1.2. No disease symptoms or detrimental effects were observed following inoculation of muskmelon seedlings by strain 4/4. In contrast, strain 15/15 caused mortality of susceptible cultivars although to a lesser extent than the wild-type isolate. Strain 4/4 colonized a variety of muskmelon and watermelon cultivars. In muskmelon cv. Ein Dor, seedlings were dipped in a conidial suspension of strain 4/4 and planted in medium amended with the mutant to achieve 100% colonization of roots and between 30 to 70% of the lower stem tissues 7 days after planting. Similar percent colonization of watermelon seedlings by strain 4/4 was recorded. In cross-protection experiments with muskmelon cultivars, significant reduction in seedling mortality was observed between 4/4-colonized FOM1.2. challenged plants compared with that of wild-type challenged plants alone. Similarly, strain 4/4 was able to significantly reduce mortality of watermelon seedlings caused by F. oxysporum f. sp. niveum race 2. This novel approach of generating nonpathogenic mutants for biological control in Fusarium spp. and other fungal pathogens from virulent wild-type isolates may be beneficial for control, because the mutant strains, lacking only in pathogenicity, may compete more efficiently than other biocontrol organisms against the pathogen of origin.

An endophytic chitinase-producing isolate of Actinoplanes missouriensis, with potential for biological control of root rot of lupin caused by Plectosporium tabacinum

2003 ◽  
Vol 51 (3) ◽  
pp. 257 ◽  
Author(s):  
Khaled A. El-Tarabily
Keyword(s):  
Biological Control ◽  
Cell Wall ◽  
Root Rot ◽  
Germ Tube ◽  
First Record ◽  
Plant Roots ◽  
Wild Type ◽  
Type Isolate ◽  
Cell Wall Lysis

Twenty-one streptomycete and 15 non-streptomycete actinomycetes were isolated from surface-disinfested lupin roots and evaluated for their potential to produce chitinase and to inhibit the growth of Plectosporium tabacinum, the causal agent of lupin root rot in Egypt. The most inhibitory isolate was identified as Actinoplanes missouriensis which produced relatively high levels of chitinase and degraded the hyphae of P.�tabacinum in vitro, causing extensive plasmolysis and cell-wall lysis. A crude culture filtrate of A. missouriensis exhibited antifungal activity and significantly (P < 0.05) reduced spore germination and germ-tube growth of the pathogen. The antagonist was recovered from inside the root at all samplings up to 8 weeks after inoculation, indicating that the roots of healthy lupin may be a habitat for the endophyte. A. missouriensis significantly (P < 0.05) reduced the severity of root rot under glasshouse conditions. An endophytic isolate of Actinoplanes italicus incapable of producing chitinase and a mutant strain of A. missouriensis that did not produce detectable levels of chitinase, did not lyse hyphae of P. tabacinum or reduce root rot in the glasshouse experiments, although colonisation of the lupin root by both these isolates was similar to that of the chitinase-producing wild-type isolate of A. missouriensis. This study is the first record of control of a soil-borne plant pathogen by a chitinolytic actinomycete, endophytic in plant roots.

The use of a benomyl-resistant mutant to demonstrate latency of Colletotrichum gloeosporioides in avocado fruit

1993 ◽  
Vol 44 (4) ◽  
pp. 763 ◽  
Author(s):  
LM Coates ◽  
JAG Irwin ◽  
IF Muirhead
Keyword(s):  
Life Cycle ◽  
Ultraviolet Light ◽  
Growth Rates ◽  
Colletotrichum Gloeosporioides ◽  
Resistant Mutant ◽  
Field Conditions ◽  
Wild Type ◽  
Type Isolate ◽  
Avocado Fruit ◽  
First Time

A benomyl-resistant mutant of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc., generated by irradiating a wild-type isolate of the fungus with ultraviolet light, was used as a marker organism to demonstrate latency under field conditions. This mutant could be easily distinguished from wild-type isolates of C. gloeosporioides on the basis of growth rates on benomyl-amended media, and was as virulent in avocado fruit as wild-type isolates. Through the use of this mutant in field inoculations of avocado fruit, it was possible to demonstrate conclusively the existence, for the first time, of latency in the life cycle of C. gloeosporioides in this host. It was also shown that the fungus was able to remain latent for periods of at least 6 months.

Selection of strains of Epicoccum purpurascens for tolerance to fungicides and improved biocontrol of Sclerotinia sclerotiorum

1990 ◽  
Vol 36 (11) ◽  
pp. 754-759 ◽  
Author(s):  
Ting Zhou ◽  
R. D. Reeleder
Keyword(s):  
Biological Control ◽  
Key Words ◽  
Sclerotinia Sclerotiorum ◽  
Fungicide Resistance ◽  
White Mold ◽  
Wild Type ◽  
Type Isolate ◽  
Type Strains ◽  
Selection Of

A wild-type isolate of Epicoccum purpurascens was exposed to shortwave ultraviolet light. One of the resulting cultures (M-20-A) was grown on media amended with the fungicides iprodione or vinclozolin and fungicide-tolerant strains were obtained. Several comparisons were made between new strains and the wild type. Sporulation was improved compared with the wild type. Strains varied in their tolerance to iprodione and vinclozolin but were not tolerant to the fungicide benomyl. Strains R4000, 16-B, and 7-A inhibited Sclerotinia sclerotiorum in vitro more than either the wild type or M-20-A, and exhibited improved control of white mold of bean in the greenhouse compared with M-20-A. Key words: biological control, fungicide resistance, white mold, iprodione, vinclozolin.

scholarly journals Stress-induced expression of IPT gene in transgenic wheat reduces grain yield penalty under drought

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Ailin Beznec ◽  
Paula Faccio ◽  
Daniel J. Miralles ◽  
Leonor G. Abeledo ◽  
Cecilia Decima Oneto ◽  
...  
Keyword(s):  
Grain Yield ◽  
Bread Wheat ◽  
Transcriptional Control ◽  
Field Conditions ◽  
Wild Type ◽  
Ipt Gene ◽  
Receptor Like Kinase ◽  
Biomass Components ◽  
Yield Penalty ◽  
Wild Type Control

Abstract Background The heterologous expression of isopentenyl transferase (IPT) under the transcriptional control of the senescence-associated receptor-like kinase (SARK) promoter delayed cellular senescence and, through it, increased drought tolerance in plants. To evaluate the effect of pSARK::IPT expression in bread wheat, six independent transgenic events were obtained through the biolistic method and evaluated transgene expression, phenology, grain yield and physiological biomass components in plants grown under both drought and well-irrigating conditions. Experiments were performed at different levels: (i) pots and (ii) microplots inside a biosafety greenhouse, as well as under (iii) field conditions. Results Two transgenic events, called TR1 and TR4, outperformed the wild-type control under drought conditions. Transgenic plants showed higher yield under both greenhouse and field conditions, which was positively correlated to grain number (given by more spikes and grains per spike) than wild type. Interestingly, this yield advantage of the transgenic events was observed under both drought and well-watered conditions. Conclusions The results obtained allow us to conclude that the SARK promoter-regulated expression of the IPT gene in bread wheat not only reduced the yield penalty produced by water stress but also led to improved productivity under well-watered conditions.

scholarly journals “Predator-In-First”: A Preemptive Biological Control Strategy for Sustainable Management of Pepper Pests in Florida

2020 ◽  
Vol 12 (18) ◽  
pp. 7816
Author(s):  
Vivek Kumar ◽  
Lucky Mehra ◽  
Cindy L. McKenzie ◽  
Lance S. Osborne
Keyword(s):  
Biological Control ◽  
Pest Management ◽  
Control Strategy ◽  
Frankliniella Occidentalis ◽  
Management Strategies ◽  
Control Program ◽  
Field Conditions ◽  
High Rate ◽  
Polyphagotarsonemus Latus ◽  
Consistent Performance

The early establishment of a biocontrol agent in the production system, whether in the greenhouse, nursery, or field, is essential for the success of the biological control program, ensuring growers’ profitability. In an effort to develop a sustainable pest management solution for vegetable growers in Florida, we explored the application of a preemptive biological control strategy, “Predator-In-First” (PIF), in regulating multiple pepper pests, Bemisia tabaci Gennadius, Frankliniella occidentalis Pergande, and Polyphagotarsonemus latus Banks under greenhouse and field conditions during different growing seasons. In these studies, two bell pepper cultivars (7039 and 7141) and the phytoseiid mite Amblyseius swirskii Athias–Henriot were used as a model system. Pepper seedlings (~8 week) of each cultivar were infested with varying rates of A. swirskii (20 or 40 mites/plant or one sachet/10 plant) and allowed to settle on plant hosts for a week before planting in pots or field beds. Results showed a comparative consistent performance of the treatment with the high rate of phytoseiids (40 mites/plant) in regulating B. tabaci and F. occidentalis populations in greenhouse studies, and B. tabaci and P. latus pests under field conditions. During two fall field seasons, higher marketable yields of 12.8% and 20.1% in cultivar 7039, and 24.3% and 39.5% in cultivar 7141 were observed in the treatment with the high rate of phytoseiids compared to the untreated control, indicating yield benefits of the approach. The outcome of the study is encouraging and demonstrates that PIF can be an important tool for organic vegetable growers and a potential alternative to chemical-based conventional pest management strategies. The advantages and limitations of the PIF approach in Florida pepper production are discussed.

Farnesol restores wild-type colony morphology to 96% of Candida albicans colony morphology variants recovered following treatment with mutagens

Genome ◽  
2006 ◽  
Vol 49 (4) ◽  
pp. 346-353 ◽  
Author(s):  
Ellen C Jensen ◽  
Jacob M Hornby ◽  
Nicole E Pagliaccetti ◽  
Chuleeon M Wolter ◽  
Kenneth W Nickerson ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Quorum Sensing ◽  
Environmental Conditions ◽  
Budding Yeast ◽  
Colony Morphology ◽  
Morphological Transition ◽  
Strongly Correlated ◽  
Wild Type ◽  
Hyphal Morphology

Candida albicans is a diploid fungus that undergoes a morphological transition between budding yeast, hyphal, and pseudohyphal forms. The morphological transition is strongly correlated with virulence and is regulated in part by quorum sensing. Candida albicans produces and secretes farnesol that regulates the yeast to mycelia morphological transition. Mutants that fail to synthesize or respond to farnesol could be locked in the filamentous mode. To test this hypothesis, a collection of C. albicans mutants were isolated that have altered colony morphologies indicative of the presence of hyphal cells under environmental conditions where C. albicans normally grows only as yeasts. All mutants were characterized for their ability to respond to farnesol. Of these, 95.9% fully or partially reverted to wild-type morphology on yeast malt (YM) agar plates supplemented with farnesol. All mutants that respond to farnesol regained their hyphal morphology when restreaked on YM plates without farnesol. The observation that farnesol remedial mutants are so common (95.9%) relative to mutants that fail to respond to farnesol (4.1%) suggests that farnesol activates and (or) induces a pathway that can override many of the morphogenesis defects in these mutants. Additionally, 9 mutants chosen at random were screened for farnesol production. Two mutants failed to produce detectable levels of farnesol.Key words: farnesol-remedial mutants, farnesol-sensing mutants, farnesol-synthesis mutants, quorum sensing, Candida albicans, morphological transition.

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