What is the total number of chromosomes in an endosperm cell (of corn) after the first round of cell division

Question

In corn there are 10 chromosomes per set and the species is diploid. A karyotype was performed from the endosperm cells grown in tissue culture in a medium containing colchicine.

Answer 1

Endosperm of corn is typically triploid, so there would be a total of 30 chromosomes in normal endosperm cells.  This is because endosperm is fomred from one pollen cell (sperm) and 2 polar bodies (female).  If the endosperm cells were cultured in a solution containing colchicine and allowed to undergo one round of cell division, the viable cells would contain 6 sets of chromosomes (60 chromosomes total or 6n).  The reason for this is that colchicine is a nasty chemical that inhibits spindle formation during mitosis and as a result, the duplicated chromosomes are not pulled into separate dughter cells.  Colchicine is used to generate plants referred to as "double haploids".