On/off button on plants’ alarm system discovered

WASHINGTON - A group of biologists has discovered an on/off button on plants’ alarm system.

When attacked by herbivores or pathogens, plants respond by activating defense programs that drive off or even kill the attackers. These defense responses require a great deal of the plant’s energy and reserves, which would otherwise be invested in growth and reproduction. Therefore, it’s very important to strictly control the activity of defense genes. Hormones, such as the jasmonates, are crucial in this process - and the plant produces these hormones when subjected to stress conditions.

The presence of the jasmonates sets a complex chain reaction in motion, starting with the degradation of the so-called JAZ proteins. This in turn frees up another protein (MYC2), which is the signal for launching the genetic defense programs and stopping the plant’s growth. The presence of the JAZ proteins keeps the defense mechanism ‘turned off’. Until now, it has been unclear how the JAZ proteins are able to block the MYC2 protein’s activity.

Courtesy the work of Laurens Pauwels and Jan Geerinck from the team of Alain Goossens (VIB/Ghent University), that problem has now been clarified.

It has been claimed that a newly discovered protein called NINJA (Novel INteractor of JAZ) connects the JAZ proteins with still another protein called TPL. As long as these proteins appear as a trio, they bind to MYC2 and that protein remains inactive. The moment that the JAZ proteins disappear - as the consequence of stress and the subsequent production of the jasmonates - MYC2 springs into action, triggering the plant’s defense mechanism.

The researchers have worked with Spanish colleagues from the CSIC/University of Madrid and have used a proteomics-based technology developed by Geert De Jaeger (VIB/Ghent University) and Erwin Witters (VITO/University of Antwerp). This technology makes it possible to determine the composition and production of protein complexes in plants. (ANI)