The present invention relates to expression cassettes comprising transcription regulating sequences with root-preferential or root-specific expression profiles in plants obtainable from Arabidopsis thaliana genes At1g66280, At1g74500, At1g49570, At1g70710, At5g66690, At3g29630, At5g48070, or At4g17800. The expression cassettes according to the present invention may be employed for expression of a protein, or expression of an antisense RNA, sense or double-stranded RNA. Preferably, expression of the nucleic acid sequence confers to the plant an agronomically valuable trait. Vectors comprising such expression cassette, and transgenic host cell or non-human organism comprising the expression cassette or the vector is also enclosed. Also enclosed is a method for identifying and/or isolating a sequence with root-specific or root-preferential transcription regulating activity.