Key gene links auxin and cytoskeleton to control plant growth

The hormone auxin is a central player in regulating plant growth and development. The feedback loop between auxin signalling and the cytoskeleton is an essential component of this role. 

A research team led by Dabing Zhang of Shanghai Jiao Tong University and including Malcolm Bennett of the University of Nottingham and King Saud University has identified that the rice morphology determinant (RMD) gene may be at the heart of this loop. The results were published in the Proceedings of the National Academy of Sciences¹.

The team investigated the altered growth pattern of rice plants with a mutant RMD gene. These mutants have short, wavy roots thanks to changes in the arrangement of their cytoskeleton. 

The researchers discovered that the roots respond weakly to auxin treatment, suggesting that RMD mediates auxin's effect on the cytoskeleton. In addition, they showed that RMD expression is directly regulated by auxin.

In turn, RMD controls the distribution of auxin throughout the root. Auxin cannot diffuse freely through plant tissues. It needs certain exporters on the cell membrane to allow it to move, whose positioning is largely controlled by the cytoskeleton. RMD therefore modulates the auxin pattern by altering its transport through its effect on cytoskeletal dynamics.

According to Bennett, “RMD functions to provide fine control of organ growth by auxin. In the future, RMD will provide a novel tool with which to manipulate auxin-regulated organ growth.”

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