Abstract
Over 1600 genes encoding transcription factors have been identified in the Arabidopsis genome sequence. However, their physiological functions are not yet fully understood. In this study, a small subfamily of single-Myb transcription factor genes, designated as RSM1-RSM4 (RADISLIS-LIKE SANT-MYB 1-4), was characterized. Here, we mainly examined the RSM1 gene, suggesting that this gene plays a role with a close connection to the HLS1 (HOOKLESS 1) gene during the early morphogenesis. The etiolated seedlings overexpressing RSM1 showed several phenotypes similar to those of hls1-1, namely, lack of apical hook with short hypocotyls, and defectiveness in gravitropism. Both RSM1-ox and hls1-1 seedlings were hypersensitive to red light during the early photomorphogenesis, thereby displaying shorter hypocotyls than do the wild type seedlings. These results will be discussed in the context that RSM1 might be implicated in the HLS1-mediated auxin signaling, which is responsible for regulation of the early photomorphogenesis of Arabidopsis thaliana.
