API/website for blasting peptide sequence against database of all plant proteomes I would like to blast a peptide sequence against all available plant proteome databases, i.e. a blastp metaproteome analysis.

What tools are available? Which database can I use?
A simple BLAST on the UniProt website does the trick (target database plants). 

Best matches are subsequences ETVEREKE and EKKRRETV in Green alga and Eelgrass respectively.