水稻非整倍体无性繁殖过程中的遗传稳定性

无性繁殖是保存非整倍体的一个有效手段。为研究该过程中非整倍体的遗传稳定性, 从水稻第8染色体短臂端三体(2n+·8S)自交后代中筛选出相应端四体(2n+·8S+·8S), 其田间性状表现为植株矮小, 叶片非常窄且内卷, 结实率差。在多年无性繁殖过程中, 该端四体所添加的其中1条·8S容易丢失使无性系产生性状变异。通过FISH分析发现该无性变异系的原始系中所添加的2条·8S, 其中1条·8S在着丝粒区域检测不到水稻着丝粒的基本组分CentO序列, 但可以检测到水稻着丝粒的另一基本组分CRR序列, 该染色体可以稳定遗传; 另外1条·8S在着丝粒区域同时检测不到CentO和CRR序列, 该染色体不能稳定遗传。而在最初保存的相应端三体亲本材料的·8S中, 同时包含CentO和CRR序列。说明·8S上的CentO和CRR在多年的组织培养过程中会随机丢失, 导致含有·8S的非整倍体在无性繁殖过程中的遗传不稳定性。

Genetic Stability of Rice Aneuploid during Its Asexual Propagation

Telotetrasome is a kind of aneuploid with two additional identical telocentric chromosomes. To investigate the genetic stability of riceaneuploid during its asexual propagation,a telotetrasome (2n+·8S+·8S) was selected from the progenies of a rice telotrisome (2n+·8S), and preserved by asexsual reproduction. But one of the extra short arms (·8S) was easy to be lost in the asexual propagation offspring of 2n+·8S+·8S and led to morphological variations. FISH results indicated that one of the two extra ·8S was short of detectable rice centromeric satellite repeat (CentO) and centromere-specific retrotransposon (CRR) and could not be transmitted stably. The other extra ·8S contained CRR, but not detectable CentO and could be transmitted steadily. However, the extra ·8S contained the CentO and CRR sequences simultaneously in the initial telotrisomic line (2n+·8S). These results showed that CentO and CRR of the extra ·8S may be randomly lost and led inheritance instability in the aneuploid harbouring extra ·8S during asexual propagation.