amyloplasts, statoliths & mutants

[Peter at carrot.mcb.uconn.edu]

Until last week I thought that the perception of the gravitational field by 
statocytes in the root cap was one of the few solved puzzles in the 
gravitropic response.  However, I learned during a discussion that starch 
free Arabidopsis mutants (which, I assume cannot use amyloplasts as 
statoliths) do have a gravitropic response (although I read in the 
Salisbury and Ross' plant physiology textbook that the response is slower).  
Has anyone looked at the ultrastructure of the root cap in the mutant?  
Does anyone have a convincing idea to save amyloplasts as statoliths? 

Peter Gogarten
Peter at carrot.mcb.uconn.edu