Production of monosomic alien addition lines of Oryza sativa having a single chromosome of O. officinalis

Abstract

Eighteen accessions of Oryza officinalis from different countries were crossed as males with three improved plant type breeding lines of O. sativa. Crossability of the two species was 1.0% to 2.3%. Viable F₁ hybrids could be obtained only after embryo culture. The F₁ hybrids had 24 chromosomes, showed no chromosome pairing during meiosis, and were completely sterile. Upon backcrossing with the respective female parents they produced a few BC₁ progenies, most of which were allotriploid and also completely male sterile. The second backcross yielded 94 plants. Of the 70 BC₂ plants so far examined, 35 have 2n + 1 chromosomes. These represent monosomic alien addition lines that have the complete chromosome complement of O. sativa and one alien chromosome of O. officinalis. These monosomic alien addition lines resemble the primary trisomics of O. sativa.