DEVELOPMENT OF MONOTELOSOMIC AND MONOACROSOMIC ALIEN ADDITION LINES IN RICE (ORYZA-SATIVA L) CARRYING A SINGLE CHROMOSOME OF O-PUNCTATA KOTSCHY

Three monotelosomic alien addition lines (MtAALs: 2n=2x+1t) and one mo noacrosomic alien addition line (MaAAL: 2n=2x+1a) of japonica rice cul tivar Nipponbare, each carrying a single chromosome of a diploid strai n of O. punctata (W1514) were isolated from the progenies of respectiv e monosomic alien addition lines (MAAL: 2n=2x+1) for chromosomes 2, 4, 7 and 9 of O. punctata. Among them, three were classified as MtAALs c arrying extra telocentric chromosomes 2 and 7, and an extra short arm of chromosome 9 in addition to the diploid complement based on the mit otic and meiotic chromosome analysis. The remaining one was similarly classified as a MaAAL carrying an extra acrocentric chromosome consist ing of a complete short arm and a heterochromatic proximal region of t he long arm of chromosome 4. Three MtAALs were designated as MtAALs 2, 7, and 9S (short arm of chromosome 9), respectively and one MaAAL was designated as MaAAL 4S(4L). Their morphology, seed fertility and the transmission rates of the extra chromosome were compared with those of the respective primary trisomics and MAALs. The plant morphology of M tAAL 2 and MaAAL 4S(4L) was similar to that of the respective MAALs, w hile the plant morphology of MtAAL 9S was similar to that of the disom ics. The plant morphology of MtAAL 7 was similar to that of the second ary trisomics for the short arm of chromosome 7. The seed fertility wa s higher than that of the respective MAALs, suggesting that the additi on lines carrying a small chromosome fragment such as telosome or acro some could give rise to functional gametes. The transmission rates of the extra chromosome were similar to those of the respective MAALs. Mo st of the PMCs in the MtAALs and the MaAAL showed a 12 II + 1 I (telos ome or acrosome) configuration at the diakinesis and first metaphase. These facts suggest that the extra telocentric or acrocentric chromoso mes originated from a misdivision of an alien univalent at anaphase I or anaphase II of the respective MAALs and the following chromosome br eakage.