Though few transcriptomes and ESTs are available, yet not a single root specific promoter has been characterized so far and I am curious to know about the pitfalls and challenges in doing the same.
Read the following article you may get answer for your question.
"Analysis of a cane root-specific promoter sequence:" seems that specific gene is well expressed in roots under certain range of stress conditions only, not in leaves, stems or healthy field-grown roots.
EXPRESSION OF FOREIGN GENES IN SUGARCANE R.G. Birch, et a1.