Welcome to the Lloyd Lab

We are studying how cytoplasmic microtubules help regulate the shape of plants.

In non-dividing cells, microtubules move along the cytoplasmic face of the plasma membrane by treadmilling (opposite end assembly/disassembly) and one of our major goals is to understand how the seemingly random interactions result in a globally organized microtubule array We developed ways of imaging fluorescent microtubules over many hours in Arabidopsis plants. This showed that successive microtubules move along tracks or bundles ( Chan et al., [2007] Nature Cell Biology, 9:171). The tracks themselves move slower than the constituent microtubules, describing rotary movements over hours.

Others have shown that cellulose synthesizing enzymes move along microtubule tracks and we are investigating how the rotary movements affect the pattern in which layers of cellulose are deposited in the cell wall.

When cells divide, microtubules form different structures involved in segregating the chromosomes to the daughter cells then placing a new cross-wall between them. The alignment of this cross-wall is key to understanding how plant cells are arranged in tissues and organs. In a proteomic search we isolated a novel microtubule-associated protein, AIR9.

This protein appears in the preprophase band of microtubules that transiently forecasts the division plane. AIR9 then reappears in the predicted site just as the new cross-wall attaches to the parental call (see Buschmann et al., [2006] Current Biology 16:38). This may provide clues to the way in which the division plane is predicted before division then memorized until the new cross-wall is laid down.

We are also fascinated by the way that microtubules bunch together to form the template for the thickened bands of cell wall that characterize xylem cells. Xylem tracheary elements undergo programmed cell death to leave hollow tubes that transport solutes from root to shoot. Before the cells die, the microtubules aggregate in hoops, helices or more complex patterns.

These lay the foundation for the mirror image patterns of thickened cell wall that will prevent the hollow transport tube from collapsing. We are looking at this process in single Arabidopsis suspension cells and are investigating how various microtubule-associated proteins modulate the wall pattern.

The Lloyd Lab

Welcome to the Lloyd Lab