Moses Lake, WA 98837, USA

New research looks at how water movement in plants is controlled

Staff Writer

PULLMAN — In the 1960s, the herbicide 2,6-Dichlorobenzonitrile came into use by farmers to control weeds. Today, it is still use in Washington state to get rid of the horsetail weed in orchards.

Why it worked, no one knew. But in a Swedish research paper, published in 2008 by Royal Institute of Technology in Sweden, researchers suggested that MAP20, or microtubule-associated protein, might be what 2,6-Dichlorobenzonitrile targets.

Two Washington State University researchers, Andrei Smertenko and Karen Sanguinet, wanted to know more and began researching MAP20.

As plants take up water from the soil, the water is transported through the plant by specialized cells. Unlike the human bloodstream that allows water and nutrients to flow freely, the water in plants must be passed through the plant from cell to cell. The water goes through special pits in the cells that serve as ports of entry and exit.

What Smertenko and Sanguinet discovered is that MAP20 acts as a structure or scaffolding for constructing pits in the water-transporting cells. It is also responsible for how large or small the pits openings are.

“This is fundamental for water movement in plants,” Smertenko said. “Plants have the incredible ability to change their body structure.”

In wet environments, plants will enlarge the size of their pits.

“When there is less water, big pits are a bad idea,” Smertenko said. “The water-transporting cells can fill with air and the air pockets move from vascular cell to vascular cell through the pits. If the pits are wide, air can move and block water movement through plant. MAP20 is the mechanism for plants to change their body structure, change the size of the pits and prevent embolism.”

As part of the research, Sanguinet experimented with Brachypodium distachyon, a sister species of wheat and barley.

“It originated in the same area where wheat was domesticated,” Sanguinet said. “They share a lot of the same features.”

Sanguinet said that by studying MAP20 in a model plant, otherwise known as a weed, what they learn can then be used in crops.

“The goal is to have tools to engineer plant bodies,” Smertenko said. “Once the technology exists, we can improve the anatomy of the cells.”

The researchers see their discovery as potentially beneficial for developing plants suited for drought-ridden environments. This process can be accomplished through breeding or through gene editing.

“The quicker way is gene editing,” Sanguinet said. “We specifically target regulatory regions of a gene and modify that up or down to regulate the expression of a given gene.”

Smertenko and Sanguinet have more research and questions that they want to answer surrounding the role of MAP20 and how it works in crops. But first they need to secure more funding to continue.

“These are very exciting biological questions,” Smertenko said. “Every protein is regulated in their own unique way. We don’t know what to expect. We might find other surprises on how to control MAP20 production.”

Rachal Pinkerton may be reached via email at