鹅观草属——人工合成双二倍体(2n=10x=70)的细胞学及育性的研究

本文对缘毛鹅观草(Roegneria pendulina)、鹅观草(R.tsukushiensis var.transiens)及其人工合成杂种F_1、双二倍体进行了细胞学,育性等的分析和研究。结果表明双亲的减数分裂,花粉育性和结实性均正常,杂种F_1的减数分裂不规则且完全不育;当代双二倍体的染色体数目为70,其减数分裂构型为:6.04 Ⅰ+26.21 Ⅱ+1.52 Ⅲ+1.59 Ⅳ+0.02 Ⅴ:第二代双二倍体的染色体数目为70,个别植株为69,减数分裂构型分别为:4.16 Ⅰ+27.33 Ⅱ+0.50 Ⅲ+2.16 Ⅳ和4.79 Ⅰ26.26 Ⅱ+1.13 Ⅲ+2.13 Ⅳ。与期望染色体配对模式相比,双二倍体中二价体出现的频率有明显增大的趋势。在减数分裂AⅠ和AⅡ分别观察到数目不定的落后单价体,大部份的四分体中出现了微核。双二倍体的育性得到了很大程度的恢复,其花粉可染色性及结实率分别为54.4％和64.0％。

CYTOLOGY AND FERTILITY STUDIES OF ARTIFICIAL AMPHIDIPLOIDS (2n=10x=70) OF TWO ROEGNERIA SPECIES

Cytology and fertility of Roegneria pendulina (2n=4x=28, SSYY), R. tsukushiensis var. transiens (2n=6x=42, SSHHYY) and their artificial hybrids (2n= 5x=35, HSSYY), amphidiploids (2n=lox=70, HHSSSSYYYY) were analysed and compared in this paper. Meiosis, pollen fertility and seed set of the two parental species were quite normal, while those of F1 hybrids were abnormal. Meiotic configuration of the amphidiploid which prossessed 70 chromosomes was 6.04I + 26.21Ⅱ+1.52Ⅲ+ 1.59Ⅳ + 0.02V. The second generation of the amphidiploid contained 70 chromosomes plus very few-individuals having 69 chromosomes. Meiotic configurations were 4.16 I+27.33Ⅱ+0.50Ⅲ + 2.16Ⅳ for a 70-chromosome individual, and 4.79 I+26.26Ⅱ+1.13Ⅲ+ 2.13Ⅳ for a 69-chromosome one, respectively. Frequencies of bivalents in the amphidiploids tended to increase obviously in comparison with the expected chromosome pairing model of the meiosis. Lagging chromosomes were observed at Anaphase I and II. Micronuclei were found in most quatets of the amphidiploids. Fertility of the amphidiploid was examined to be rather high with an average of 54.4% stainable pollen and 64.0% seed set, respectively.