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University
of California Riverside researchers identify key plant
enzyme that defends against multiple infections - VPEg is an
enzyme that regulates programmed cell death in plants
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Riverside, California
October 11, 2004
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 Carter, Jan Zouhar, Songqin Pan,
and Hailing Jin. Co-authors from other institutions include
Raquel Martin, Manuel Paneque and Jose Juan Sanchez-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 Julia 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.
The University of California, Riverside is a major
research institution and a national center for the
humanities. Key areas of research include nanotechnology,
genomics, environmental studies, digital arts and
sustainable growth and development. With a current
undergraduate and graduate enrollment of nearly 17,000, the
campus is projected to grow to 21,000 students by 2010.
Located in the heart of inland Southern California, the
nearly 1,200-acre, park-like campus is at the center of the
region's economic development.
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