In this invention, a method is described that allows for the efficient
creation and identification of validated biological materials that
greatly enhance the ability to perform polysome-mediated RNA profiling,
such as constitutive, cell type-, tissue type-, or condition-enhanced RNA
profiling. The method relies on the use of a tri-partite plant binary
expression vector comprised of the following components: a) a DNA
promoter element that drives expression of a sequence specific
transcription activator protein such as a LexA:Gal4 fusion protein in a
unique desired pattern, b) a DNA promoter element comprising a target
site for the transcriptional activator protein, such as opLexA, fused to
a nucleotide encoding an epitope tagged ribosomal component protein and
c) a DNA promoter element comprising a target site for the
transcriptional activator protein, such as opLexA, fused to a nucleotide
encoding an in vivo reporter protein. By visualization of the
co-regulated reporter, this method allows for in planta confirmation that
the promoter element is driving expression, such as constitutive, cell
type-, tissue type-, or condition-enhanced expression, of the tagged
ribosomal protein in the desired cell or tissue types.