Herbicide May Affect Plants Thought to be Resistant

Purdue University researchers have found a fine-tuning mechanism involved in plant root growth that led them to ask if a well-known herbicide could lead to more water and nutrient requirement.

Angus Murphy and Wendy Peer was studying the movement of the growth hormone auxin and discovered that ABCB4, the protein responsible for the transport of auxin into cells, also removes the hormone when there is a build up of auxin. According to Murphy, the herbicide 2,4-D, a synthetic form of auxin, could have unintended effects on ABCB4. The protein is located on the root surface and can be switched into intake-only surface, diabling the ability to remove too much auxin from cells, before the herbicide action can be turned off inside the plant. This would result to development of shorter root hairs.

Murphy also reported that laboratory testing of ABCB4 in yeast, tobacco and human cells subjected to 2,4-D all showed that ABCB4 could be locked into the uptake-only mode. The root hairs of mutant plants that had ABCB4 removed were not affected by application of 2,4-D. "It was very clear that what was happening in the plant was what was happening in the cell cultures," he explained.

The findings of their study suggest that application techniques that limit 2,4-D entry into soils are important to ensure that production with engineered 2,4-D resistant crop plants does not require additional fertilizer and/or water inputs.

For more information, read the article at http://www.purdue.edu/newsroom/research/2011/111122MurphyTransporter.html.