U   .   W     .   N    E  W     S     FROM THE UNIVERSITY OF WISCONSIN NEWS SERVICE, MADISON 6, WISCONSIN
8/13/58 cfg                        RELEASE:               PM's of Wednesday, Aug. 27
BLOOMINGTON, Ind.--(Advance for PM's of Aug. 27)--A University of Wisconsin
scientist said Wednesday morning that parasitic plant diseases are actually furthered
by metabolic changes in the infected host plant, and not solely through self-action
of the parasite.
The statement came in a paper, "Metabolic ConsideraVions of Obligate
Parasitism," by Prof. Paul J. Allen, associate professor o'otanjat t eUniversity
/  1   /  ,
of Wisconsin. The paper was delivered in the Symposium on Physiology of Pakasitis*
of the American Phytopathological Society which is holding its Golden Jubilee
meetings in conjunction with the American Insitute of Biological Sciences at Indiana
University Aug. 24-28.
Diseases of plants incited by obligate parasites are distinguished from
other diseases by prolonged survival of the diseased tissues. A relation resembling
"peaceful co-existence" is established between the host and parasite, during which both
the host cells remain alive and active and the parasite also grows and reproduces.
During this period of "peaceful co-existence" profound disturbances occur
in the chemical transformation of the host plant. Test analysis of the parasite
at various stages of the disease development has shown that much of the change occurs
in the host and is not due to the metabolism of the parasite.
Continuing sickness of the plant is the immediate result of the host's own
activities and many of the disease symptoms are exaggerations of a normal activity.
The changes in the host are important in providing the parasite with
nutrients needed for development since investigation has found that the changes
preceded the rapid development of the parasite. The changes in the host are inter-
rupted in resistant plants and the parasite stopped developing.
The changes, which are induced by the parasite, alter the host in such
fashion as to provide a more suitable nutrient environment for the parasite, and
thereby actually further the disease, Prof. Allen said.