NATURAL DOUBLING OF CHROMOSOMES OF HYBRIDS BETWEEN WHEAT AND RYE

Using nine varieties of wheat(Triticum)as female and two varieties of rye (Secale)as male, we made these crosses separately, and obtained hybrid plants from some crosses by embryo cultures.However, the F₁'s seeds were obtained only from the crosses of the two ryes with Stewart durum wheat(T. durum cv.Stewart). It is shown that natural doubling of chromosomes needs specifically genetic background(s).In Stewart×S. cereale the unreduced gametes were produced from pollen mother cells, and these F₁ hybrids were amphidiploids. The process of gametic production is similar to that of normal somatic division.Although the process of gametic formation was normal in Stewart×S.montanum, the numbers of chromosome of formed gametes were l～2l respectively. Thus, in the F₁'s seeds from this cross there were both amphidiploids and partial amphidiploids. Hence there are differences between Stewart×S. cereale and Stewart×S. montanum on the formation of amphidiploid.