Abstract
To understand the mechanism of abiotic stress tolerance, we have analyzed salt sensitive mutants of rice. We recently identified a novel gene, RSS3 (Rice Salt Sensitive3), which has an important role for normal root growth. Under salty condition, rss3 mutant shows severely inhibited root growth, accompanied by morphological aberrancy, whereas rss3 causes decrease in number of crown root under non-stress condition. RSS3 has a domain that is highly conserved among plant bHLH transcription factors, but lacks a DNA binding domain. This raises a possibility that RSS3 regulates activity of bHLH factors, through competitive binding of a protein recognizing the conserved domain. In this scenario, rss3 might affect expression of portions of genes regulated by bHLH factors. We have analyzed RNA expression profiles in root of rss3, and found striking changes of expression pattern of genes by rss3. Altered responses to plant hormones in rss3 will also be discussed.
