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Accueil du site → Doctorat → Egypte → Occurrence, Pathogenicity and Physiology of Pythium Species Associated to Some Wild Plants in Egypt

Minia University (2010)

Occurrence, Pathogenicity and Physiology of Pythium Species Associated to Some Wild Plants in Egypt

Moharam, Sahar Ali.

Titre : Occurrence, Pathogenicity and Physiology of Pythium Species Associated to Some Wild Plants in Egypt

Auteur : Moharam, Sahar Ali.

Etablissement de soutenance : Minia University

Grade : Doctor of Philosophy (PhD) in Botany 2010

Résumé partiel
Pythium is a large and important genus in the class Oomycetes. It is cosmopolitan and can be found as saprophytes, parasites, facultative parasites or mutualistic ; aquatic, amphibious or terrestrial fungi. They occur most abundantly in cultivated soils near the rhizosphere of cultivated and wild plant region and less commonly in non-cultivated soil. In Egypt, little attention has been paid to the isolation and identification of Pythium species from rhizosphere soils of wild plants. This work was undertaken to obtain information about the occurrence, identification, physiology of reproduction, pathogenicity and biological control efficiency of Pythium species in different localities in Egyptian soils particularly in the rhizosphere zone of different wild plants growing in Egypt. Three hundred and seven isolates belonging to 6 species of Pythium were isolated from the rhizosphere soil of 37 different plant species growing in different localities in Egypt. The (6) isolated different species of Pythium, which were identified on both morphological and molecular basis are : P. aphanidermatum (Edson) Fitzp, P. diclinum Tokunaga, P. irregulare (Buisman), P. longisporangium (Paul), P. oligandrum Drechsler, P. ultimum Trow var. ultimum. P. aphanidermatum was the most predominant species in the rhizosphere soil of the different wild plants studied. Ninety isolates of P. aphanidermatum, representing 29.3% of the total Pythium isolates and were obtained from the rhizosphere soil of Avena fatua, Emex spinosa, Sensio desfontanei, Conyza dioscoridis, Sonchus oleraceus, Amaranthus sp., Cynodon dactylon and Salicornia fruticosa plants growing in Botanical garden of Department of Botany and Microbiology, Minia University in the spring of (2008) ; Minia city, in front of Alragaa farm, a reclaimed farm in the western desert (2006) and (2008) ; Bank of the River Nile at Assiut city (2008) ; At the end of the road side from Assiut to the New Valley (Kharga) (2006) ; Gezeret Sharona a Nile island near Maghagha, Minia (2007) and (2008) ; Ekhsas island in the River Nile in Minia city (2006) and (2008) ; Fayoum at Shalshuk closed to Qaroon lake (2005). On the other hand, moderate isolations were recorded for P. ultimum var. ultimum and seventy-five isolates representing 24.4% occurrence, were isolated from the rhizosphere soil of Avena fatua, Cynodon dactylon, Conyza dioscoridis, Sonchus oleraceus, Zygophyllum coccenum, Imperata cylindrica, Sensio desfontainei and Alhagi maurorum growing in Botanical garden of Department of Botany and Microbiology, Minia University in the spring of (2006) ; Bank of the River Nile at Assiut city (2005, 2007) ; Bank of Ibrahimia canal at Assiut city (2007), Hagool valley , suez (2006), Ekhsas island in the River Nile in Minia city (2007) ; Fayoum at Shalshuk closed to Qaroon lake (2008). Sixty isolates of P. diclinum, representing 19.5% occurrence, were isolated from the rhizosphere soil of Chenopodium album, Malva parviflora, Zygophyllum coccinium, Sonchus oleraceus, Beta vulgaris, Mesembriyanthemum nodiflorum, Sensio vulgaris, Melilotus indica, Sensio desfontainei, Amaranthus ascendens, Phragmites communis and Zygophyllum album growing in the Botanical garden of Department of Botany and Microbiology, Minia University in the spring of (2005, 2008) ; Estern desert opposite to Mallawy city, Minia governorate (2006) ; Bank of the River Nile at Assiut city (2006, 2008) ; Bank of Ibrahimia canal at Assuit city (2006) ; At the end of the road side from Assiut to the New Valley (Kharga) (2005) ; Gezeret Sharona a Nile island near Maghagha, Minia (2006, 2008) ; Ekhsas island in the River Nile in Minia city (2006, 2008). Fourty isolates of P. oligandrum representing 13% occurrence, were isolated from the rhizosphere soil of Chenopodium album, Sonchus oleraceus, Amaranthus sp., Melilotus indica, Imperata cylindrica , Phragmites communis plants growing in Botanical garden of Department of Botany and Microbiology, Minia University in the spring of (2007) ; Bank of the River Nile at Assiut city (2006) ; Bank of Ibrahimia canal at Assiut city (2005) ; Gezeret Sharona, a Nile island near Maghagha, Minia (2006, 2007) ; Ekhsas island in the River Nile in Minia city (2005) ), Fayoum at Shalshuk closed to Qaroon lake (2007) and Fayoum, Shalalat, Wadi Elrayan (2008). This fungus is a special interest since it is used as a biological control agent of some fungal diseases.

Présentation étendue (EULC)

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