Apomictic maternal diploids in tetraploid Job's tears.

Two cases of reversion to diploidy were observed in autotetraploid Job's tears (Coix lacryma-jobi L. 4n = 40) out of a total of 1,112 plants examined over a period of 7 years. One of these was a trisomie (2n = 21) and the other a disomic (2n = 20), derived from apomictic development ofn+1 andn maternal gametes of the tetraploid, respectively. In some respects both these derivatives differed from the original diploid that gave rise to the tetraploid through colchicine treatment. The potentialities of such reversions in the evolution of new diploid races are discussed.