Melanin-independent accumulation of turgor pressure in appressoria of Phakopsora pachyrhizi

Chang, Hao-Xun

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https://hdl.handle.net/2142/50523 Copy

Description

Title

Melanin-independent accumulation of turgor pressure in appressoria of Phakopsora pachyrhizi

Author(s)

Chang, Hao-Xun

Issue Date

2014-09-16

Director of Research (if dissertation) or Advisor (if thesis)

Hartman, Glen L.

Department of Study

Crop Sciences

Discipline

Crop Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Appressorium
• Turgor pressure
• Melanin
• Soybean
• Phakopsora pachyrhizi

Abstract

Appressoria of some plant pathogenic fungi accumulate turgor pressure that produces a mechanical force enabling the direct penetration of hyphae through the epidermis. Melanin functions as an impermeable barrier to osmolytes, which allows appressoria to accumulate high turgor pressure. Deficiency of melanin in appressoria reduces turgor pressure and compromises the infection process. In Phakopsora pachyrhizi, the soybean rust pathogen, the appressoria are hyaline. Our objective was to ensure the absence of a melanin layer specifically between the appressorial cell wall and plasma membrane, as well as to determine the turgor pressure of P. pachyrhizi appressoria. We demonstrated that two melanin biosynthesis inhibitors neither reduced turgor pressure nor compromised the infection process. Transmission electron microscopy also showed the absence of a melanin layer between the appressorial cell wall and plasma membrane. In addition, the turgor pressure of P. pachyrhizi appressoria ranged from 5 to 6 MPa based on extracellular osmolytes used to simulate different osmotic pressures. This is the first report showing that turgor pressure accumulation of P. pachyrhizi appressoria was independent of melanin.

Graduation Semester

2014-08

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http://hdl.handle.net/2142/50523

Copyright and License Information

Copyright 2014 Hao-Xun Chang

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