Use expression/bquote functions with AnnotationTrack group/feature/id

[Billy-lm]

Hi,

I would like to ask for some tricks on the use of expression/bquote functions with group/feature/id elements in the AnnotationTrack. Rather than setting normal names (characters) to these elements, sometimes we way want to plot with some complex strings including superscripts, subscripts, Greek alphabets, etc.
For my case, I intend to set p-values for some peak regions detected. When I tried with simple characters, everything is fine.
AT = AnnotationTrack(range = TF_binding_site, genome = "hg38", id = paste0("p=10^-", mcols(TF_binding_site)$p_value))
plotTracks(AT, ...)

But when I tried to make the use of expression/bquote functions like this:
AT = AnnotationTrack(range = TF_binding_site, genome = "hg38", id = as.expression(sapply(mcols(TF_binding_site)$p_value, function(var) bquote(p == 10^-.(var)))))
plotTracks(AT, ...)
I got errors as:
Error in h(simpleError(msg, call)) : error in evaluating the argument 'f' in selecting a method for function 'split': cannot coerce class '"expression"' to a data.frame
Are there any solutions for this?
Thanks a lot in advance!

Mu