四倍体栽培棉与二倍体野生棉杂种PMC-FISH研究

摘要

首次将PMC-FISH(花粉母细胞荧光原位杂交)技术应用于四倍体栽培棉与二倍体野生棉杂交所形成的三倍体杂种棉F1中,成功的鉴定了目标染色体中的单价体、双价体、多价体,还发现在非目标染色体上有星状和片段状的杂交信号.在以A组棉基因组DNA作为探针的PMC-FISH中,分别对三倍体杂种棉F1及其母本四倍体栽培棉的减数分裂中期I的染色体构型进行了鉴定.结果显示,四个三倍体杂种棉F1的减数分裂时期染色体的构型分别是:陆地棉(AD)1×雷蒙德氏棉(D5)为1IIIaad + 1IIaa + 4IIad + 7IIdd + 5Ⅰa + 7Ⅰd;海岛棉(AD)2×旱地棉(D4)为1Ⅴaaaad +1IIIadd + 2IIad + 8IIdd + 6Ⅰa + 5Ⅰd;陆地棉(AD)1×澳洲棉(C3)为2IIIadd (adc or acc) + 1IIaa + 9Ⅰa + 4IIcc (dc or dd) + 14Ⅰd (c);陆地棉(AD)1×南岱华棉(C1-n)为:1IIaa + 1IIad (ac)+ 10Ⅰa + 6IIcc (dc or dd) + 13Ⅰd (c).然而,两个四倍体棉染色体的构型都是13IIaa + 13IIdd.上述结果还显示, AD×D的两个杂种组合中,二价体多,单价体少,AD×C的两个杂种组合中,二价体少,单价体多;并且AD×D型杂种中A亚组染色体单体的数目比其在AD×C型杂种中的更少.这说明,与C染色体组相比较,D染色体组与四倍体棉种的亲缘关系更近.同时,我们的结果也证明PMC-FISH技术在分析三倍体杂种棉F1的亲缘关系中起着不可取代的作用.%PMC-FISH (pollen mother cell-fluorescence in situ hybridization) technology was firstly applied to identify probed chromosomes in univalent, bivalent and multivalent, as well as to distinguish star- or fragment-like hybridization signals from non-probed chromosomes in four triploid F1 hybrids produced by cultivated allotetraploid cotton crossed with different diploid cotton species in the genus Gossypium. Using genomic DNA from A genome species as probe, the meiotic chromosome configurations in metaphase Ⅰof four triploid F1 hybrids were identified as 1Ⅲaad + 1Ⅱaa + 4Ⅱad + 7Ⅱdd + 5Ⅰa + 7Ⅰd for (AD)1D5 (G. hirsutum × G. raimondii), 1Ⅴaaaad +1Ⅲadd + 2Ⅱad + 8Ⅱdd + 6Ⅰa + 5Ⅰd for (AD)2D4 (G. barbadense × G. aridum), 2Ⅲadd (adc or acc) + 1Ⅱaa + 9Ⅰa + 4Ⅱcc (dc or dd) + 14Ⅰd (c) for (AD)1C3 (G. hirsutum × G. australe), and 1Ⅱaa + 1Ⅱad (ac)+ 10Ⅰa + 6Ⅱcc (dc or dd) + 13Ⅰd (c) for (AD)1C1-n (G. hirsutum × G. nandewarense), respectively. While the two cultivated tetraploid species, G. hirsutum (AD)1 and G. barbadense (AD)2, which were used for the triploid female parents, displayed the same chromosome configuration as 13Ⅱaa + 13Ⅱdd. It is obvious that there were more bivalents but less univalents in ADD [(AD)1D5 and (AD)2D4] type than that in ADC [(AD)1C3 and (AD)1C1-n] type of triploid F1 hybrids and with fewer A-subgenome univalents and more A-subgenome combined pairings in ADD than in ADC type of triploid F1 hybrids. The results indicated that specific relationship of AD cultivated tetraploid species with D genome may be much closer than with C genome, and that the PMC-FISH technology may play an irreplaceable role in the specific relationship analyses of triploid F1 hybrids in Gossypium.