UC Riverside Researchers Identify Key Plant Enzyme

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UC Riverside Researchers Identify Key Plant Enzyme That Defends

Against Multiple Infections

VPEg is an Enzyme that regulates programmed cell death in plants

(October 7, 2004)

http://www.newsroom.ucr.edu/cgi-bin/display.cgi?id=894

Natasha Raikhel

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RIVERSIDE, Calif. – www.ucr.edu – Scientists from the University of

California, Riverside have identified one of the key enzymes that

trigger programmed cell death, an important process plants undergo

in fighting off bacterial, fungal or viral infections. The

development holds out hope of improving crop yields, which are

dependent on plants being able to fend off multiple types of

pathogens.

The findings, outlined in a paper titled " VPEg Exhibits a Caspase-

like Activity that Contributes to Defense Against Pathogens " were

reported in the Sept. 23, online issue of Current Biology, and

involve research on the key plant protein, vacuolar processing

enzyme or VPEg, in Arabidopsis thaliana, or thale cress, that is

required for this process.

Programmed cell death (PCD), which occurs naturally in all multi-

cellular organisms, is the regulated elimination of cells that

happens during the course of development, as well as in response to

bacterial, fungal and viral infection. Caspases are a family of

proteases, or enzymes that degrade proteins, which play an essential

role in initiating and carrying out programmed cell death in

animals.

Caspase-like activities have also been shown to be required for the

initiation of programmed cell death in plants, but the genes

controlling those activities have not been identified.

Natasha Raikhel, Director of the UCR Center for Plant Cell Biology,

and her former postdoctoral researcher, Enrique Rojo, have now shown

that this key plant protein contributes to defense against

bacterial, fungal and viral pathogens in plants by activating

programmed cell death pathways.

They have discovered that mutants lacking this protein have an

increased susceptibility to these pathogens. These results have

significant influence in the outcome of a diverse set of plant-

pathogen interactions and suggest that this key plant protein is

likely involved in a variety of processes that range from stress and

defense responses to proper development during aging.

This is an important discovery because it demonstrates a previously

unknown mechanism through which plants control cell

death. " Programmed cell death is a universal process that all

multicellular organisms must control throughout growth and

development, " explained Raikhel. " Since PCD plays such a central

role in a wide variety of physiological processes, the VPE pathway

for controlling PCD likely has a huge impact on this process in

plants. "

The research, funded by the National Science Foundation, was carried

out from 2002-2004 in the Department of Botany and Plant Sciences

and the Center for Plant Cell Biology (CEPCEB) at UC Riverside and

the Universidad Autónoma de Madrid.

Besides Raikhel and Rojo, UCR co-authors of the Current Biology

paper include Clay , Jan Zouhar, Songqin Pan, and Hailing Jin.

Co-authors from other institutions include Raquel ,

Paneque and -Serrano of the Departamento de

Genética Molecular de Plantas del Centro Nacional de Biotecnología,

Consejo Superior de Investigaciones Cientificas, Madrid, Spain;

Frederick M Ausubel and Plotnikova of the Department of

Genetics at Harvard Medical School and the Department of Molecular

Biology at Massachusetts General Hospital, Boston; and Barbara Baker

of the Plant Gene Expression Center at UC Berkeley & the U.S.

Department of Agriculture.

Additional Contacts:

Natasha Raikhel

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