Cytological Studies of Sterility in Hybrids between Distantly Related Varieties of Rice, Oryza stativa, L

Abstract

With a number of rice varieties and their F₁ hybrids, the behavior of chromosomes in pollen mother cells was investigated. The occasional occurrence of univalent chromosomes, “stretched chromosomes”, and anaphasic bridges was pointed out. All of these abnormalities were found both in F₁ plants and in parental pure lines, and in the frequency of occurrence of these phenomena, the F₁ and parental plants did not differ significantly. Thus the anaphasic bridge cannot be attributed to inversion. An explanation may be that they come from an occasional reunion of sister chromatids after a breakage at the diplotene stage in meiosis.