hort.net Seasonal photo, (c) 2006 Christopher P. Lindsey, All Rights Reserved: do not copy
articles | gallery of plants | blog | tech blog | plant profiles | patents | mailing lists | top stories | links | shorturl service | tom clothier's archive0
Gallery of Plants
Tech Blog
Plant Profiles
Mailing Lists
    Search ALL lists
    Search help
    Subscription info
Top Stories
sHORTurl service
Tom Clothier's Archive
 Top Stories
New Trillium species discovered

Disease could hit Britain's trees hard

Ten of the best snowdrop cultivars

Plant protein database helps identify plant gene functions

Dendroclimatologists record history through trees

Potato beetle could be thwarted through gene manipulation

Hawaii expands coffee farm quarantine

Study explains flower petal loss

RSS story archive

RE: ploidy


>However, there are four sets of chromosomes in a tetraploid, rather 
>than two, so that you have five possible combinations of alleles at 
>each locus, rather than three.

Allow me to throw in some other considerations.  I think Ben got 
confused because he was thinking about segregation ratios from the 
point of a autotetraploid rather then an ampidiploid.  Segeration 
ratios from autotetraploids can be variable.  However, autotetraploids 
are rarely fertile to any extent.  With an amphidiploid every gene is 
basically duplicated, like in an autotetraploid, but you get some 
addition factors to consider with the five possible combinations you 

In an amphidiploid the combination BBbb comes in two forms - BB//bb 
and Bb//Bb, where the "//" seperates the two genomes.  If you self the 
Bb//Bb plant you can recover the recessive phenotype (15:1 
dominant:recessive; 1/4 x 1/4), but if you self the BB//bb plant all 
the progenies are dominant and of genotype BB//bb.

If you take a dominant complementary gene and throw in an inhibitor 
gene and then duplicate that on the second genome, you can quickly see 
how figuring out segregation ratios in an amphidiploid can become very 
difficult.  And a dominant complimentary gene with an inhibitor is a 
SIMPLE system!  Then, throw in some transposable elements to mess 
things up and....

Joe Halinar

To sign-off this list, send email to majordomo@mallorn.com with the

 © 1995-2017 Mallorn Computing, Inc.All Rights Reserved.
Our Privacy Statement
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index