Functional annotation with nr database followed by GO enrichment analysis

Question

[hellokwmin]

Dear Stars,

I am working in the field of plant biology. I usually performed functional annotation using Araport database (i.e. Arabidopsis database) After functional annotation, I could perform GO enrichment analysis using R wherein there is library called "Org.At.tair.db" (also Arabidopsis database)

But problem is when I am using nr database. To my best knowledge, there is no library of "nr database" so that I have a difficulty in performin GO enrichment analysis using R... Is there any alternative ways to solve my problem? R is, as far as I know, the best way to customize the figure for GO analysis and other too..