There was none, but there is a shortcut for italic now.
To use the shortcut, user must have installed at least LibreOffice 5.4. The addition of markup italic and strikethrough is noted in LibreOffice 5.4 release note.
*bold* to make strong text i.e. bold
/italic/ to emphasize text i.e. italic
-strikethrough- to strike text i.e.
_underline_ to underline text (not shown here due to limitation on SE)
Where to check
The shortcuts are handled by AutoCorrect in LibreOffice and AutoCorrect in OpenOffice. To see the option, go to Tools > AutoCorrect > AutoCorrect Options and select "Options" tab.
AutoCorrect has now improved options for bold, italic, strikethrough and underline. In LibreOffice 5.3 and older, the options were limited to bold and underline (bottom half).
The following limitation applies:
- User can only enable or disable the shortcuts all together or none, but not individually.
- User can not change the existing in-line shortcuts to something else.
What about MediaWiki syntax
Some users may think of text formatting markup by MediaWiki. LibreOffice does have an extension for MediaWiki, which is available in the repository or the local repository.
$ apt-cache search libreoffice wiki
libreoffice-wiki-publisher - LibreOffice extension for working with MediaWiki articles
libobasis5.3-extension-mediawiki-publisher - MediaWiki publisher extension for LibreOffice 5.3 .0.3
Unfortunately, MediaWiki extension is for publishing purpose.
The indended use is to export styles and formatting in LibreOffice to MediaWiki format and not the other way round. So users who expect
''italic'' to become italic or
'''bold''' to become bold would be not possible in LibreOffice.
Using keyboard shortcut
Alternatively, LibreOffice Help explains that applying text formatting while you type for italic is possible using the keyboard shortcut.
To apply italic formatting
Select the text that you want to format.
You can also press Ctrl+I, type the text that you want to format in italic, and then press Ctrl+I when you are finished.
Tested using LibreOffice 5.3 and LibreOffice 5.4 in Xubuntu 14.04.