Underline Text

Software : Docbook xml 4.4 CR2, xsl 1.67.2, fop 0.20.5, saxon 6.5.3

When I use the following markup, the pdf output has the 'space' between 
'P' and 'granule' also underlined.  The space should not be underlined. 
  Could someone please comment.

<emphasis role="underline">P</emphasis> <emphasis 
role="underline">g</emphasis>ranu<emphasis 
role="underline">l</emphasis>e defective


Cheers,        Tristan
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Tristan J. Fiedler
Postdoctoral Fellow - Stein Lab
Cold Spring Harbor Laboratory