Oomycete zoospores

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... 

Figure (2). Structure of some host-specific attractants for oomycete zoospores...

Motile zoospores are an important means of initiating infection by oomycetes. Zoospores do not divide, however, but have high-affinity... 

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)... 

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

Table 6. Concentration of Nicotinamide (34) to Inhibit Motlity of Peronosporomycetes (Oomycetes) Zoospores [105].

So far, the repellent activity of estrogenic compounds toward trivial oomycete zoospores has not been reported [123]. 

Table L Diverse Stimuli Triggering Characteristic Behaviors and/or Morphological Changes of Aphanomyces cochUoides or Other Peronosporomycetes (Oomycetes) Zoospores...

The saponins such as avenacin Ai which is released from oat roots are known to be lytic to a broad range of oomycete zoospores. Our screening assays revealed that crude extract of stem bark bom an Anacardiaceae plant, Lannea coromandelica had similar properties. A solution of 200 ppm of the crude extract was found to inhibit the motility of the zoospores and subsequently cause them to lyse (3i). 

Our screening tests to find plimt secondary metabolites interacting with the life cycle development of oomycete zoospores revealed that both host and nonhost metabolites can regulate some key steps in the life cycle of oomycete... 

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