Abstract
In several angiosperm species, excised plant tissues give rise to the entire organism through transdifferentiation from differentiated cells to stem cells when cultured with phytohormones including auxin. However, the action mechanism of auxin on this process has remained elusive. In our current study with Physcomitrella, which has a high-capacity for transdifferentiation, we show that the anti-auxin probe BH-IAA suppresses transdifferentiation from leaf cells to stem cells. Because BH-IAA blocks auxin response through the suppression of the SCFTIR1-Aux/IAA pathway and the transcriptional regulation by auxin response factors (ARFs), the transcriptional network of ARFs is likely to be important in transdifferentiation of leaf cells. As a first step to elucidate this network, we isolated 13 ARF genes from Physcomitrella, and found 2 to 3 splice variants of 4 genes. In addition, we will show recent studies on the expression of ARFs during transdifferentiation and the phenotypes of transgenic lines expressing high levels of ARFs.
