Identification of root-preferential transcription factors in rice by analyzing GUS expression patterns of T-DNA tagging lines

Abstract

T-DNA tagging lines are useful for analyzing the functions of genes and regulatory elements. We have previously generated approximately 100,000 insertional mutants in japonica rice (Oryza sativa), using T-DNA vectors carrying the promoter-less GUS reporter gene. In this study, we conducted GUS assays of seedlings from 430 lines in which TDNA was inserted into transcription factor genes. Among the 75 lines that showed GUS signals, nine displayed an endospermpreferential expression pattern; two lines demonstrated GUS signals in both endosperm and roots; 21 lines had GUS expression mainly in leaves; 19 lines showed GUS signal in both leaves and roots; and 24 lines expressed GUS predominantly in the roots. Co-segregation analyses of 49 homozygous lines indicated that the GUS expression patterns observed from 38 lines were due to the T-DNA insertion. We also identified fusion transcripts between tagged genes and the GUS reporter in six lines. Quantitative RT-PCR confirmed that the GUS expression patterns of those tagged lines indeed represent organ- and tissue-preferential expression of the tagged genes. The GUS-tagged transcription factor lines identified here will be useful for functional analysis of these candidates.