Effects of Trichoderma on sexual reproduction of some species of Pythium and Phytophthora

1978 ◽  
Vol 56 (14) ◽  
pp. 1651-1654
Author(s):  
R. H. Haskins ◽  
N. R. Gardner
Keyword(s):  
Sexual Reproduction ◽  
Direct Contact ◽  
Phytophthora Cinnamomi ◽  
Apparent Effect ◽  
Trichoderma Spp ◽  
Volatile Products ◽  
Pythium Acanthicum

Pythium and Phytophthora cultures were subjected to volatile products from cultures of several Trichoderma spp., as well as to killed mycelium and extracts therefrom. Oospores were produced by Pythium acanthicum and P. arrhenomanes and by one strain of each of the compatible heterothallic pairs of P. sylvaticum and P. catenulatum tested, only in the presence of a suitable sterol. The volatile products of the Trichoderma spp. tested had no apparent effect on oospore production. Direct contact with Trichoderma mycelium, or fat-solvent extracts of such mycelium, resulted in oospore production by P. acanthicum. Such oospore production was likely due to the presence of sterols in the Trichoderma. Similarly, with the compatible pairs of Phytophthora cinnamomi tested, oospores were produced by paired cultures or, in some cases, by the 'A2' strains alone, only in the presence of a suitable sterol, whether or not volatile products from Trichoderma cultures were provided to the growing organisms.

Continuing variation in successive asexual generations of Phytophthora cinnamomi following sexual reproduction

1996 ◽  
Vol 74 (7) ◽  
pp. 1181-1185 ◽  
Author(s):  
X. B. Zheng ◽  
W. H. Ko
Keyword(s):  
Sexual Reproduction ◽  
Phytophthora Cinnamomi ◽  
Type A ◽  
Colony Type ◽  
Uniform Pattern ◽  
Parental Type ◽  
Respective Parent ◽  
Different Types

Colony-type stability of asexual progeny of selfed-oospore cultures of Phytophthora cinnamomi was investigated. Progeny were divided into parental type A, types B to E for those different from type A but with a distinct uniform pattern, and type M for those with the overlapping appearance of two different types. Colonies derived from three successive zoospore generations of isolate P630 were of the same parental A type. However, colonies from oospores of the same isolate consisted of types A, B, C, D, E, and M. Some of the oospore cultures of type A or B and all the type M oospore cultures produced zoospores containing more than one type. Oospore cultures of types C, D, or E that were tested produced zoospores with the same colony type as their respective parent. Among the five cultures randomly selected from asexual progeny produced by oospore isolates P630-21 and P630-6, four displayed continuing variation in colony type in the three to five successive zoospore generations tested. Keywords: asexual variation, continuing variation, Phytophthora cinnamomi, sexual reproduction.

The ultrastructure of sexual reproduction in Pythium acanthicum

1976 ◽  
Vol 54 (19) ◽  
pp. 2193-2203 ◽  
Author(s):  
R. H. Haskins ◽  
J. A. Brushaber ◽  
J. J. Child ◽  
L. B. Holtby
Keyword(s):  
Endoplasmic Reticulum ◽  
Sexual Reproduction ◽  
Contact Zone ◽  
Periplasmic Space ◽  
Spine Development ◽  
Storage Body ◽  
Cytoplasmic Ribosomes ◽  
Pythium Acanthicum ◽  
Hyphal Tip

The young oogonium and young antheridium in Pythium acanthicum Drechsler are densely and randomly packed with numerous mitochondria, dictyosomes, nuclei, interlocking vacuoles of several types, some of which contain a dense storage body, a variety of vesicles, endoplasmic reticulum, and cytoplasmic ribosomes. Wall vesicles, evenly distributed next to the plasma-lemma in rapidly growing oogonia, become localized in groups at points where they appear to initiate the hyphal tip-like development of the oogonial spines. They are also found on both sides of the antheridium−oogonium contact zone. Spine development starts shortly after antheridium−oogonial contact is made and ceases with entry of antheridial material into the oogonium. Excess nuclei, mitochondria, and various organelles are abandoned in the periplasmic space, where they normally quickly disintegrate when the oospore is formed. The periplasmic space is invaded frequently by vegetative hyphae originating outside of the oogonium.

scholarly journals Control of root rot (Phytophthora cinnamomi) in avocado (Persea Americana) with bioagents

2020 ◽  
Vol 46 (3) ◽  
pp. 205-211
Author(s):  
Ciro Hideki Sumida ◽  
Lucas Henrique Fantin ◽  
Karla Braga ◽  
Marcelo Giovanetti Canteri ◽  
Martin Homechin
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Persea Americana ◽  
Field Conditions ◽  
In Vitro Tests ◽  
Trichoderma Spp ◽  
Maize Cultivation ◽  
Antagonistic Potential

ABSTRACT Despite the favorable edaphoclimatic conditions for avocado production in Brazil, diseases such as root rot caused by the pathogen Phytophthora cinnamomi compromise the crop. With the aim of managing root rot in avocado, the present study aimed to evaluate chemical and biological control with isolates of Trichoderma spp. and Pseudomonas fluorescens. Thus, three assays were conducted to assess: (i) mycelial inhibition of P. cinnamomi by isolates of Trichoderma spp. and P. fluorescens from different crop systems; (ii) effect of autoclaved and non-autoclaved metabolites of P. fluorescens, and (iii) chemical or biological treatment of avocado seedlings on the control of root rot under field conditions. The isolates of Trichoderma spp. from maize cultivation soil and the commercial products formulated with Trichoderma presented greater antagonism (p <0.05) to the pathogen P. cinnamomi in the in vitro tests. Similarly, non-autoclaved metabolites of P. fluorescens presented antagonistic potential to control P. cinnamomi. Under field conditions, the fungicide metalaxyl and the bioagents showed effectiveness in controlling P. cinnamomi, as well as greater root length and mass. Results demonstrated potential for the biological control of avocado root rot with Trichoderma spp. and P. fluorescens.

Isozyme Variability in Field Populations of Phytophthora cinnamomi in Australia

1988 ◽  
Vol 36 (3) ◽  
pp. 355 ◽  
Author(s):  
KM Old ◽  
MJ Dudzinski ◽  
JC Bell
Keyword(s):  
Sexual Reproduction ◽  
Phytophthora Cinnamomi ◽  
Soil Samples ◽  
Mating Types ◽  
South Eastern ◽  
Enzyme Loci ◽  
Eastern Australia ◽  
Wide Range ◽  
Isozyme Variability ◽  
South Eastern Australia

Isozyme characteristics of 280 isolates from populations of Phytophthora cinnamomi in native veg- etation in six locations in south-eastern Australia were examined at 19 enzyme loci. No new enzyme genotypic arrays were identified as compared with earlier samplings. This work indicates that the low variability for P. cinnamomi in Australia obtained in earlier work, from separate isolates in a wide range of locations, is paralleled in detailed population samples in south-eastern Australia. At one location, A1 and A2 mating types coexisted in soil samples. The lack of recombinants in these population samples suggests an absence of sexual reproduction in the field.

scholarly journals Antagonistic Potential of Native Trichoderma spp. against Phytophthora cinnamomi in the Control of Holm Oak Decline in Dehesas Ecosystems

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 945
Author(s):  
Francisco J. Ruiz-Gómez ◽  
Cristina Miguel-Rojas
Keyword(s):  
Root Rot ◽  
Mycelial Growth ◽  
Phytophthora Cinnamomi ◽  
Antagonistic Activity ◽  
Selective Medium ◽  
Trichoderma Spp ◽  
Phytophthora Root Rot ◽  
Alternative Measures ◽  
Oak Mortality ◽  
Antagonistic Potential

Phytophthora root rot caused by the pathogen Phytophthora cinnamomi is one of the main causes of oak mortality in Mediterranean open woodlands, the so-called dehesas. Disease control is challenging; therefore, new alternative measures are needed. This study focused on searching for natural biocontrol agents with the aim of developing integrated pest management (IPM) strategies in dehesas as a part of adaptive forest management (AFM) strategies. Native Trichoderma spp. were selectively isolated from healthy trees growing in damaged areas by P. cinnamomi root rot, using Rose Bengal selective medium. All Trichoderma (n = 95) isolates were evaluated against P. cinnamomi by mycelial growth inhibition (MGI). Forty-three isolates presented an MGI higher than 60%. Twenty-one isolates belonging to the highest categories of MGI were molecularly identified as T. gamsii, T. viridarium, T. hamatum, T. olivascens, T. virens, T. paraviridescens, T. linzhiense, T. hirsutum, T. samuelsii, and T. harzianum. Amongst the identified strains, 10 outstanding Trichoderma isolates were tested for mycoparasitism, showing values on a scale ranging from 3 to 4. As far as we know, this is the first report referring to the antagonistic activity of native Trichoderma spp. over P. cinnamomi strains cohabiting in the same infected dehesas. The analysis of the tree health status and MGI suggest that the presence of Trichoderma spp. might diminish or even avoid the development of P. cinnamomi, protecting trees from the worst effects of P. cinnamomi root rot.

Competition between Phytophthora cinnamomi and Trichoderma spp. in autoclaved soil

1976 ◽  
Vol 22 (8) ◽  
pp. 1120-1127 ◽  
Author(s):  
W. D. Kelley ◽  
R. Rodriguez-Kabana
Keyword(s):  
Phytophthora Cinnamomi ◽  
Trichoderma Spp ◽  
Trichoderma Isolate

Results from analyses of β-glucosidase (EC 3.2.1.21) and phosphatase (EC3.1.3.1; EC 3.1.3.2) activities indicated that presence of a Trichoderma isolate reduced development of Phytophthora cinnamomi. It was also observed that P. cinnamomi was more competitive in coinoculated cultures than in cultures where Trichoderma was added on day 3. Analysis of trehalase (EC 3.2.1.28) activity indicated that Trichoderma either utilized portions of the P. cinnamomi mycelium as substrate or the action of P. cinnamomi released additional nutrients not normally available to Trichoderma. The stronger Trichoderma isolate was T. harzianum.

Fungicide treatment of sunflower seed to inhibit germination of admixed sclerotia of Sclerotinia sclerotiorum

1986 ◽  
Vol 26 (4) ◽  
pp. 489 ◽  
Author(s):  
JK Kochman ◽  
PW Langdon
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Chemical Control ◽  
Direct Contact ◽  
Sunflower Seed ◽  
Potato Dextrose Agar ◽  
Apparent Effect ◽  
Thiophanate Methyl ◽  
Fungicide Treatment ◽  
Wettable Powder ◽  
Low Levels

Sunflower seed lots infected with sclerotia of Sclerotinia sclerotiorum provide a means of dispersal of the fungus. To find a chemical control, sclerotia were dusted or dipped with 19 chemical formulations. Eight of these (benomyl 50%, benomyl 15% plus lindane 1%, thiabendazole wettable powder, thiabendazole 45% water-based flowable, iprodione 50%, dithianon 75%, omadine 50% and thiophanatemethyl 70%) completely inhibited germination of sclerotia when in direct contact with and covering the organism. Sclerotia were able to germinate if these chemicals were removed by washing, but germination was significantly lower for those sclerotia which had been treated with benomyl 50%, benomyl 15% plus lindane 1% (Bennel 13, thiabendazole 90% and 45%, iprodione 50% and thiophanate-methyl 70% than for dithianon 75% and omadine 50%. When sclerotia were buried in moist soil for 1 month those treated with formulations of benomyl, thiabendazole and iprodione did not germinate on potato dextrose agar, while the germination percentages of those treated with dithianon, ornadine and thiophanate-methyl were not significantly different from that for germination of sclerotia which had not been treated. When thiabendazole, benomyl and iprodione were used at 3 rates to treat sunflower seed infested with sclerotia, thiabendazole was the most effective fungicide in preventing germination of sclerotia. This result was confirmed when the fungicide was used commercially to treat lots of sunflower seed containing sclerotia. As thiabendazole had no apparent effect on gerrnination of sunflower seed it could be used to treat sunflower seed containing low levels of sclerotia to prevent previously uninfested areas being contaminated with S. sclerotlorum during sowing operations.

scholarly journals Pythium spp. Associated with Rooibos Seedlings, and Their Pathogenicity Toward Rooibos, Lupin, and Oat

Plant Disease ◽  
2014 ◽  
Vol 98 (2) ◽  
pp. 223-232 ◽  
Author(s):  
Amirhossein Bahramisharif ◽  
Sandra C. Lamprecht ◽  
Christoffel F. J. Spies ◽  
Wilhelm J. Botha ◽  
Frikkie J. Calitz ◽  
...  
Keyword(s):  
Phytophthora Cinnamomi ◽  
Phylogenetic Analyses ◽  
Common Species ◽  
Limited Information ◽  
Internal Transcribed Spacer Region ◽  
Pythium Irregulare ◽  
Rotation Crops ◽  
Native Site ◽  
Highly Virulent ◽  
Pythium Acanthicum

Rooibos (Aspalathus linearis) is an important indigenous crop in South Africa. Oomycetes are a common problem in rooibos nurseries, causing serious losses, but limited information is available on the species involved. Molecular and morphological analyses of 117 oomycete isolates from 19 rooibos nurseries and 33 isolates from 11 native rooibos sites revealed the presence of several Pythium spp., including Pythium acanthicum, P. irregulare, P. mamillatum, P. myriotylum, P. pyrilobum, P. cederbergense, and Pythium RB II, and Phytophthora cinnamomi (native site). Most of the species were identified in nurseries and native rooibos, with Pythium irregulare being the most common species occurring in all nurseries and 46% of the native sites. Phylogenetic analyses of the internal transcribed spacer region of the P. irregulare isolates showed that isolates within this species complex fit into three subclades, of which only two have previously been reported. On rooibos, all species except P. acanthicum and the previously characterized P. cederbergense and Pythium RB II were pathogenic and highly virulent. On lupin and oat, rotation crops in nurseries, the three aforementioned species were also nonpathogenic. All the other oomycete species were pathogenic on lupin but less so than on rooibos. On oat, only P. irregulare, P. myriotylum, and P. pyrilobum were pathogenic. This is the first report of P. mamillatum, P. pyrilobum, and P. myriotylum as pathogens of lupin, and P. irregulare and P. pyrilobum as pathogens of oat. The three nonpathogenic Pythium spp. were able to significantly reduce disease caused by pathogenic species in the less susceptible lupin and oat but not on rooibos. On lupin, the nonpathogenic species enhanced the virulence of Phytophthora cinnamomi.

Interactions of Phytophthora cinnamomi and Trichoderma spp. in relation to propagule production in soil cultures at 26 °C

1977 ◽  
Vol 23 (3) ◽  
pp. 288-294 ◽  
Author(s):  
Walter D. Kelley
Keyword(s):  
Trichoderma Harzianum ◽  
Phytophthora Cinnamomi ◽  
General Increase ◽  
Trichoderma Spp ◽  
Nonsterile Soil ◽  
Trichoderma Isolate ◽  
Inoculation Time ◽  
Simple Carbohydrates ◽  
Trichoderma Isolates ◽  
Amended Soil

Effects of Trichoderma harzianum and T. polysporum on chlamydospore production by two isolates of Phytophthora cinnamomi were determined over a 21-day period in nonsterile, sterilized, and sterilized amended soil. Trichoderma was either coinoculated with P. cinnamomi or added to the cultures on day 3 of the incubation period. In nonsterile soil, conversion of mycelial fragments in the P. cinnamomi inoculum to chlamydospores resulted in an initial slight increase in chlamydospore numbers. In cultures where either of the Trichoderma isolates was added on day 3, a significant reduction in chlamydospore numbers was observed on day 4; however, neither of the Trichoderma isolates at either inoculation time significantly affected chlamydospore numbers by day 21. Results from studies with sterilized amended soil indicated that a reduction in P. cinnamomi chlamydospore numbers by either of the Trichoderma isolates was dependent upon availability of simple carbohydrates. In sterilized nonamended soil, the number of chlamydospores was increased in cultures containing either Trichoderma isolate; in sterilized amended soil chlamydospore numbers were initially reduced, followed by a general increase as the nutrients were depleted. Neither of the Trichoderma isolates exhibited significant antagonistic qualities toward P. cinnamomi.

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