CYTOGENETIC CORRELATIONS AND CROSSING OVER 

 Polyploidy of Cells and Tissues 



105 



Within organisms of a particular ploidy, multiplication of the chromo- 

 some complement is widely found in particular cells and tissues. For 

 example, in the roots of diploid plants, the cells behind the growing 



Einkorn 



diploid, 2n = 14, 



genome A 



Wild relative 

 diploid, 2n = 14, 

 genome B 



AB 



sterile Fi 

 diploid, 2n = 14, 

 Some unreduced gametes, n = 14, 

 genome AB 



AB 



Fertile amphidiploid, 2n = 28, 



Triticum aurum = macaroni wheat 



e.g., 



Triticum dicoccoides = wild emmer 



Emmer 



amphidiploid, 2n = 28, 



genome AB 



Wild relative, Aegilops 



diploid, 2n = 14, 



genome D 



Sterile Fi 

 2n = 21 

 Unreduced gametes, n = 21, genome ABD 



Triticum vulgare = common bread wheat 

 2rt = 42, genome ABD 



FIGURE 4.7. Origin of common bread wheat, illustrating the method of evolution 

 by amphidiploid/. 



