Host-specific plant signal

Here we review our research results concerning zoospore attractants, repellents, cytotoxins and inhibitors of zoospore motility together with bioassay systems to survey chemical regulators toward zoospores. The first part of this review described some new findings on the effects of host-specific plant signals on chemotaxis and differentiation of oomycete zoospores. The potential role and mode of action of nonhost secondary... 

HOST-SPECIFIC PLANT SIGNALS REGULATING THE LIFE-CYCLE DEVELOPMENT OF OOMYCETES... 

Developmental Transitions of Zoospores Triggered by Host-Specific Plant Signals... 

Fig. (4). Morphological changes (developmental transitions) of Aphanomyces cochlioides zoospores triggered by a host-specific plant signal, cochliophilin A (3). White bars 1 jjM.

Table (2). Triggering Chemotaxis and differentiation (encystment and germination) of Some Oomycete Zoospore by Host-specific Plant Signals...

Host-specific plant signal Host planl Name of Oomycete Threshold concentration (n M) Taxis Encystment Germination Reference... 

Host-specific plant signal triggering life-cycle development of Oomycete Phytopathogens... 

Our preliminary experiments to detect the putative receptor responsible for the host-specific attractant cochliophilin A (5), by using a probe 5,7-dihydroxyflavone incorporated with 7-O-biotinyl and 4 -azido groups slmw that the receptors are locate on the cell membrane (44). Detailed characterization of the cochliophilin A receptor would be a starting point to unravel the signal transduction pathway in zoospore chemotaxis and differentiation by host-specific plant signals. 

H. P. Spaink, O. Geiger. D. M. Sheeley, A. A. N. Van Brussel, W. S. York, V. N. Reinhold, B. J. J. Lugtenberg, and E. P. Kennedy, The biochemical function of the Rhizobium leguminosarum proteins involved in the production of host-specific signal molecules. Advances in Molecular Genetics of Plant-Microbe Interactions. Vol. 1 (H. Hennecke and D. P. S. Verma, eds.), Kluwer Academic Publishers, Dordrecht, The Netherlands, 1991. 

Horvath B., Bachem, C.W.B., Schell, J. Kondorosi, A. (1987). Host-specific regulation of nodulation genes in Rhizobium is mediated by a plant-signal interacting with the nodD gene product. The EM BO Journal 6, 841-8. 

So far, there are two best documented examples of specificity in chemotaxis and subsequent differentiation of oomycete zoospores by host plant signals. The first one is the attraction, encystment and germination of A. cochlioides zoospores to a rare flavone, cochliophilin A (3), and the other one is Ph. sojae zoospores to isoflavones daidzein (4) and genistein (5)... 

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