Canalization and auxin transport

Expression of GFP tagged PIN7, an auxin transporter, in an Arabidopsis inflorescence stem (cross-section)

The regulated inter-cellular transport of the hormone auxin is a hugely important process in plant development, and is involved in the patterning of many tissues, and — at a wider scale — in communication between different organs. We are particularly interested in how the auxin transport system may allow organs to communicate without signal transmission, through a somewhat enigmatic process known as canalization.

Canalization occurs when auxin moves from an auxin ‘source’ ( a region of high concentration) to a ‘sink’ (a region of low concentration and/or fast transport). As the auxin moves, it upregulates and polarises its own transport, creating a narrow ‘canal’ of auxin transporting cells. We believe that establishment of canalized auxin transport links from organs such as branches, fruit and seed to the stem is necessary for their growth. When one organ creates a canalized link to a shared stem however, it weakens the auxin sink strength of the stem for other organs, making it more difficult to create a canalized link and to grow. In this way, organs effectively compete to export their auxin into the stem, and are able to communicate with each other without any signal transmission.

We are interested in understanding how canalization-driven feedbacks between organs may regulate reproductive architecture in flowering plants. However, we are also very interested in understanding the basis of canalization itself, and in understanding the properties of the auxin transport system.

People working on this project:

Tom Bennett

Publications

• van Rongen M, Bennett T, Ticchiarelli F, Leyser O. Connective auxin transport contributes to strigolactone-mediated shoot branching control independent of the transcription factor BRC1. PLoS Genetics 15, e1008023.
• Bennett T, Hines G, van Rongen M, Ljung K, Leyser O. (2016). Connective auxin transport in the shoot facilitates communication between shoot apices. PLoS Biology 14, e1002446.
• Bennett T. (2015). PIN proteins and the evolution of plant development. Trends in Plant Science 20, 498-507.
• Bennett TA, Liu MM, Aoyama, T, Wang XY, Bierfreund NM, Braun M, Coudert Y, Dennis RJ, O’Connor D, White CD, Decker EL, Reski R, Harrison CJ. (2014). Plasma membrane targeted PIN proteins drive shoot development in a moss. Current Biology 24, 2776-2785.
• Bennett T, Brockington S, Rothfels C, Graham S, Stevenson S, Kutchan T, Rolf M, Thomas P, Wong GK, Leyser O, Glover BJ, Harrison CJ. (2014). Paralagous radiations of PIN proteins with multiple origins of non-canonical PIN structure. Molecular Biology and Evolution 31, 2042-2060.
• Bennett T, Hines G, Leyser, O (2014). Canalization: what the flux? Trends in Genetics 30, 41-48.
• Prusinkiewicz P, Crawford S, Smith R, Ljung K, Bennett T, Ongaro V, Leyser, O. (2009). Control of bud activation by an auxin transport switch. PNAS 106, 17431-17436.
• Bennett T, Sieberer T, Willett B, Booker J, Luschnig C, Leyser O. (2006). The MAX pathway controls shoot branching by regulating auxin transport. Current Biology 16, 553-563.