玉米和类玉米杂交后代异染色质纽重复序列的遗传稳定性

【目的】探究异染色质纽在玉米、类玉米及其杂种后代染色体上分布的特点及遗传稳定性。【方法】利用组成玉米异染色质纽的180-bp重复序列和TR-1元件对二倍体多年生类玉米（Zea diploperennis， DP）、玉米自交系330及其远缘杂交后代异源种质纯系540的有丝分裂中期染色体进行荧光原位杂交，观察杂交信号在3个材料染色体上的位置、强弱及分布数量。【结果】玉米自交系330的第2、3、5、6、7号染色体长臂的近末端区显示较强杂交信号。DP的第2、3、5、6、7、8、9号染色体的长臂末端检测出异染色质纽，其中2号染色体在短臂的末端也检测到异染色质纽杂交信号。杂交后代540的第2、5、7染色体长臂近末端区检测到较强的杂交信号；3个材料的第6染色体短臂末端的随体上均显示强杂交信号。【结论】玉米大部分异染色质纽成分不能稳定遗传，其表现出来的多态性可以作为鉴定玉米和类玉米杂种后代的细胞学标记。

Genetic stability of heterochromatic knob of repetitive sequence in maize and Zea diploperennis hybrids

【Objective】Distribution characteristics and genetic stability of heterochromatic knob in maize and Zea diploperennis hybrids were studied. 【Method】Maize inbred 330, DP and alloplasmic pure line 540 were studied using the fluorescence in situ hybridization （FISH） technique with knob-associated tandem repeats 180 bp and 350 bp （TR-1）] as probes. The position, strength, and distribution number of hybridization signal in the chromosome of the three materials were observed. 【Result】The end zone of the long arm of 2, 3, 5, 6 and 7 chromosome in inbred 330 showed strong hybridization signals. Heterochromatic knob was detected in the end zone of the long arm of 2,3,5,6,7,8 and 9 chromosome as well as the end zone of the short arm of 2 chromosome in DP. Strong hybridization signals were also observed in the end zone of the long arm of 2,5 and 7 chromosome in 540. Satellites in the short arm end zone of the sixth chromosome of the three materials exhibited strong signals. 【Conclusion】The results indicated most composition in knobs can not be inherited stably. Polymorphism should be used as cellular markers for identifying maize and Zea diploperennis hybrids.