柑橘体细胞杂种有性后代花粉母细胞减数分裂的观察

Meiotic observations on pollen mother cells of sexual progenies of citrus somatic hybrid

柑橘体细胞杂种后代为三亲来源,采用酸解压片法对柑橘体细胞杂种[哈姆林甜橙(Citrus sinensis Osbeck)+粗柠檬(C.jambhiri Luss)]与单胚二倍体植株宜本杂4号[华农本地早橘(C.reticulata Blanco)×宜昌橙(C.ichangensis Swingle)]的有性杂种后代进行减数分裂观察,以明晰柑橘体细胞杂种有性后代减数分裂行为。结果表明,有性后代二倍体后代减数分裂行为与二亲杂种后代相似;三倍体后代减数分裂过程异常现象较二亲杂种后代复杂,中期Ⅰ出现56.9%的不配对染色体以及各种多价体,中期Ⅰ和中期Ⅱ观察到游离在赤道板外的染色单体,变幅为1～3个,平均比例分别为51.2%和38.68%;后期Ⅰ和后期Ⅱ观察到染色体桥及染色体断片、落后染色体;四分体时期含微核等。同时对后代植株花蕾直径与花粉母细胞减数分裂各个时期之间的关系进行了分析。

The sexual progenies of citrus somatic hybrid possess three parents＇ genetic materials. In order to investigate their cytological behavior,the sexual progenies of a cross between allotetraploid hybrid [Hamlin sweet orange（Citrus sinensis Os-back）＋Rough Lemon（C. jambhiri Luss）] （as the pollen parent） and mono-embryonic diploid type Iben No. 4 [Huanongben-dizao tangerine （C. reticulata Blanco）×Ichang papeda （C. ichangensis Swingle）] was used as materials for observing the meiotic course of their pollen mother cells. The results showed that the PMC of diploid progenies showed normal meiosis,while a series of abnormal meiotic phenomena were observed in triploid progenies,such as univalent（56.9%）and multi-valent,one to three chromosomes beside the equatorial plate at metaphaseⅠ（51.2%）or metaphaseⅡ（38.7%）. Chromosome bridges,chromosomes fragment,lagging chromosomes at anaphaseⅠor anaphaseⅡ and the small nucleus in tetrads were also frequently observed. Meanwhile,the relationship between the meiotic stage and diameter of floar bud was analyzed.