Making plants reach land

When the first plants moved from sea to land approximately 465 million years ago, they needed some sort of specialized cells for conducting water from the roots to the aerial parts. Looking for the genes that could contribute to this novel function, Misato Ohtani from RIKEN Center for Sustainable Resource Science in Yokohama, Japan compared the moss Physcomitrella patens – a non-vascular plant – with Arabidopsis thaliana. Both plants have genes encoding a group of NAC transcription factors that in land-based, vascular plants are known to oversee the development of xylem tissue, which transports water. To investigate the function of these transcription factors in the moss, the corresponding genes were knocked out, leading to malformation of its specialized water-conducting and supporting cells, hydroids and stereids. This indicates that NAC transcription factors have a very similar functional relevance for water conduction in these distantly related plants eventhough they handle the task in very different anatomical ways. The authors accordingly suggest that NAC transcription factors were involved in the ancient adaptation of plants to land.

Source: Xu et al (20 March 2014) Science doi: 10.1126/science.1248417