EFFECT OF 2, 4·DIACETYLPHLOROGLUCINOL PRODUCED BY Pseudomonas FLUORESCENS Q2-87 ON ULTRASTRUCTURE, PROTEINASE AND RIBONUCLEASE OF Pythium ultimum

Document Type : Original Article

Authors

1 Department of Agricultural Botany, Suez-Canal University, Ismailia, Egypt

2 Department of Plant Pathology, Michigan State University, East Lansing, Mil USA 48824

Abstract

Effects of exogenous application cf 2,4-diacetylphloroglucinol (2,4-DAPG)
produced by the biocontrol agent Pseudotnones fluorescens Q2-87 on ultrastructure,
activities of protease and ribonuclease (RNase) of Pyfhium ulfimum Trow were
investigated during the time-course studied after application. Electron microscopic
examination of treated Pyfhium cells relalive to the untreated ones revealed Ihat
hypha I cell walls, plasma membranes, milochonoria and nuclei membranes showed
disruption and degradation. Cytoplasm W(lS aggregated and cytoplasmic organelles
were disorganized. Increased vacuolation was also a characteristic of the treated
cells. In addition, many hyphal cells were devoid of all living components. Total
soluble proteins, protease and RNase activ ties were assayed spectrophotometrically
while native polyacrylamide gel of protease and RNase activities were analyzed by
electrophoretically. Higher levels of protease. RNase and their specific activities and
total soluble proteins were found in treated cells of Pythium compared to controls. The
present results suggest that 2,4-DAPG causes disorganization, degradation and death
later of P. ullimum by promoting elevated Ie leis of proteinase and RNase activities. It
is concluded that 2, 4-DAPG exerted its mode of biocontrol agent action by increasing
the concentration and lor activities of such hydrolytic enzymes that may affect its
normal ultrastructure

Keywords

Journal of Agricultural Chemistry and Biotechnology
Volume 29, Issue 2
February 2004
Pages 841-856

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