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Title: Role of external signals and cytosolic pH during the pre-penetration phase of infection by Magnaporthe grisea
Author: Jelitto, Till C.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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The role of external signals (particularly the substratum surface, light and nutrients) in regulating the pre-penetration phase of Magnaporthe grisea (Herbert) Barr [anamorph, Pyricularia grisea Sacc.] was analysed on rice leaves, artificial substrata and in liquid suspension. Surface contact was found to be essential for appressorium induction but not conidium germination. Both a high surface hydrophobicity and light favoured the formation of short differentiated germ tubes and large numbers of appressoria, but neither factor was essential for their induction. Light intensity had a graded effect on the lengths of differentiated germ tubes but not on the number of appressoria formed. No single sugar or nitrogen source was found to have a marked influence on appressorium formation. However, a high concentration of a complete nutrient source prevented differentiation in the dark but not in the light. Higher numbers of appressoria differentiated on rice leaves than on artificial substrata suggesting that the host provides additional factors, and thus a more conducive environment, for promoting appressorium formation. Overall, the results indicated that the pre-penetration phase of rice blast infection involves a programme of growth and differentiation triggered at conidium germination and regulated by multiple signals from the host and environment. The role of cytosolic pH (pHc) in growing germ tubes during conidium germination, germ tube growth and appressorium formation was analysed by confocal ratio imaging of the pH-sensitive fluorescent dye 5(6)-carboxyseminaphthorhodafluor-1 (SNARF-1).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available