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Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae. / Syed Farooq Abbas Shah

Swansea University Author: Syed Farooq Abbas Shah

Abstract

Nutrition influenced growth, sporulation, phenotypic stability and virulence of the insect pathogenic fimgus, Metarhizium anisopliae. Virulent conidia were produced on nutrient poor or osmotic stress media, while least virulent conidia were produced on nutrient rich media. Repeated subculturing on n...

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Published: 2004
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42294
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last_indexed 2018-08-03T10:09:46Z
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spelling 2018-08-02T16:24:28.7137853 v2 42294 2018-08-02 Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae. 3bcbc06c033e16865a17a08edb60f2da NULL Syed Farooq Abbas Shah Syed Farooq Abbas Shah true true 2018-08-02 Nutrition influenced growth, sporulation, phenotypic stability and virulence of the insect pathogenic fimgus, Metarhizium anisopliae. Virulent conidia were produced on nutrient poor or osmotic stress media, while least virulent conidia were produced on nutrient rich media. Repeated subculturing on nutrient rich media caused further attenuation of virulence, however, attenuation was strain dependant. Several strain independent parameters were identified that could be used to monitor the virulence of M anisopliae conidia during normal production or when developing new inexpensive culture media. Virulent conidia typically had high levels of spore bound Prl, a CN ratio below 5.2:1 and high germination rates. RT-PCR revealed that virulent conidia from insects contained high levels of transcripts of prl A and other pathogenicity-related genes (e.g. ste 1, try 1 and chy 1). Virulent conidia from 1% yeast extract media had higher levels of transcripts of these pathogenicity-related genes than the least virulent conidia from CN 35:1 medium (= SDA), however, levels were significantly lower than those in insect-derived conidia. This study shows for the first time that passaged inoculum is virulent irrespective of the original culture medium or insect host suggesting that starvation conditions, whether in vivo or in vitro, results in de-repression of Prl and that elevated levels of this enzyme enhance fungal virulence. Nutrition also influenced expression of other pathogenicity determinants e.g. adhesive properties of conidia (hydrophobicity, surface charge) and destruxins production, however, inconclusive relationship between these pathogenicity determinants and nutrition was observed. Nutrition also influenced fungal stability independent of strain. Under similar nutritional conditions, V275 produced fewer sectors than V245. Most sectors were sterile and produced significantly lower quantities of pathogenicity determinants. Careful selection of stable strains and manipulation of cultural conditions could be employed to enhance or stabilize virulence of M anisopliae. E-Thesis Microbiology. 31 12 2004 2004-12-31 COLLEGE NANME Biosciences COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:28.7137853 2018-08-02T16:24:28.7137853 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Biosciences Syed Farooq Abbas Shah NULL 1 0042294-02082018162443.pdf 10798002.pdf 2018-08-02T16:24:43.1770000 Output 13507139 application/pdf E-Thesis true 2018-08-02T16:24:43.1770000 false
title Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae.
spellingShingle Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae.
Syed Farooq Abbas Shah
title_short Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae.
title_full Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae.
title_fullStr Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae.
title_full_unstemmed Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae.
title_sort Influence of nutrition on the virulence and stability of the insect-pathogenic fungus Metarhizium anisopliae.
author_id_str_mv 3bcbc06c033e16865a17a08edb60f2da
author_id_fullname_str_mv 3bcbc06c033e16865a17a08edb60f2da_***_Syed Farooq Abbas Shah
author Syed Farooq Abbas Shah
author2 Syed Farooq Abbas Shah
format E-Thesis
publishDate 2004
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Biosciences{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Biosciences
document_store_str 1
active_str 0
description Nutrition influenced growth, sporulation, phenotypic stability and virulence of the insect pathogenic fimgus, Metarhizium anisopliae. Virulent conidia were produced on nutrient poor or osmotic stress media, while least virulent conidia were produced on nutrient rich media. Repeated subculturing on nutrient rich media caused further attenuation of virulence, however, attenuation was strain dependant. Several strain independent parameters were identified that could be used to monitor the virulence of M anisopliae conidia during normal production or when developing new inexpensive culture media. Virulent conidia typically had high levels of spore bound Prl, a CN ratio below 5.2:1 and high germination rates. RT-PCR revealed that virulent conidia from insects contained high levels of transcripts of prl A and other pathogenicity-related genes (e.g. ste 1, try 1 and chy 1). Virulent conidia from 1% yeast extract media had higher levels of transcripts of these pathogenicity-related genes than the least virulent conidia from CN 35:1 medium (= SDA), however, levels were significantly lower than those in insect-derived conidia. This study shows for the first time that passaged inoculum is virulent irrespective of the original culture medium or insect host suggesting that starvation conditions, whether in vivo or in vitro, results in de-repression of Prl and that elevated levels of this enzyme enhance fungal virulence. Nutrition also influenced expression of other pathogenicity determinants e.g. adhesive properties of conidia (hydrophobicity, surface charge) and destruxins production, however, inconclusive relationship between these pathogenicity determinants and nutrition was observed. Nutrition also influenced fungal stability independent of strain. Under similar nutritional conditions, V275 produced fewer sectors than V245. Most sectors were sterile and produced significantly lower quantities of pathogenicity determinants. Careful selection of stable strains and manipulation of cultural conditions could be employed to enhance or stabilize virulence of M anisopliae.
published_date 2004-12-31T03:52:41Z
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score 11.012678

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