12个竹种的45S rDNA和5S rDNA分布特性比较

Comparison of 45S rDNA and 5S rDNA Distribution Characteristics of 12 Bamboo Species

【目的】分析12个竹种的45S rDNA和5S rDNA分布特征,并调查这些竹种的染色体数目和结构,为竹类植物系统分类和染色体结构等研究提供相应的细胞遗传学资料,为相关的染色体识别提供相应的染色体物理标记。【方法】以毛竹、花毛竹、龟甲竹、早竹、金镶玉竹、白哺鸡竹、紫竹、斑竹、黄秆乌哺鸡竹、人面竹、大明竹和茶秆竹为材料,以45S rDNA和5S rDNA为探针,采用双色荧光原位杂交技术分析45S rDNA和5S rDNA在这些竹种染色体上的分布。【结果】1)12个竹种的染色体数目均为2 n=48,45S rDNA在12个竹种染色体上展现出一定的多态性分布。①毛竹、花毛竹、龟甲竹、早竹、黄秆乌哺鸡竹和斑竹均具有2个45S rDNA位点,且2个45S rDNA位点信号强度和分布位置表现一致。②茶秆竹、人面竹、白哺鸡竹和金镶玉竹也具有2个45S rDNA位点,其中1个位点较为稳定,位于染色体末端,另外1个位点断裂严重,经常脱离分布位置。③紫竹和大明竹具有2个45S rDNA位点,这对位点在信号强度上存在较大差异,特别是紫竹表现更明显。2)5S rDNA在12个竹种染色体上展现出了一定的多态性分布。①毛竹、花毛竹和龟甲竹的5S rDNA分布模式相似,具有2对信号强度不同的5S rDNA位点,其中1对5S rDNA位点信号很强,位于染色体末端,另外1对5S rDNA位点信号微弱,位于染色体近中间区域。②早竹、白哺鸡竹和黄秆乌哺鸡竹的5S rDNA分布模式较为相似,具有2对较强的5S rDNA信号,且2对信号强度差异不大,以成对形式位于2对同源染色体近中间区域。③金镶玉竹、紫竹和大明竹的5S rDNA分布模式比较特殊,均有3个位点,明显不对称,其中紫竹的3个5S rDNA位点,2个位于染色体末端,1个位于染色体近中间区域,金镶玉竹的3个5S rDNA,2个强弱不同的信号位于染色体中间,还有1个位于染色体末端,而大明竹的3个5S rDNA均位于染色体近中间区域。④斑竹与人面竹的5S rDNA分布模式非常相似,具有2对5S rDNA位点,且信号较弱,均位于染色体近中间区域。⑤茶秆竹具有1对较弱的5S rDNA位点,位于染色体短臂近着丝粒区域。【结论】1)根据45S rDNA和5S rDNA在金镶玉竹、紫竹、人面竹、白哺鸡竹、大明竹和茶秆竹染色体上的分布特征,推测这些竹种的染色体可能发生过断裂、易位、删除或插入等遗传重组。2)毛竹、花毛竹和龟甲竹3个竹种的45S rDNA和5S rDNA分布模式非常相似,该分布模式与3个竹种系统分类地位具有一定的一致性。

【Objective】Bamboo is a facultative reproductive plant,with a large number of varieties and variants.Are there differences in chromosome number and structure among these bamboos?To solve these problems,the distribution characteristics of 45S rDNA and 5S rDNA of 12 different bamboo species was studied,meanwhile its chromosome number and structure was revealed,in order to provide corresponding chromosome physical markers for related chromosome recognition.【Method】In this study,Phyllostachys edulis,P.edulis‘Tao kiang’,P.edulis‘Heterocycla’,P.violascens,P.aureosulcata‘Spectabilis’,P.dulcis,P.nigra,P.reticulata‘Lacrima-deae’,P.vivax f.aureocaulis,P.aurea,Pleioblastus gramineus and Pseudoasa amabilis were selected as materials,and 45S rDNA and 5S rDNA were used as probe.The distribution of 45S rDNA and 5S rDNA on the chromosomes of the 12 different bamboo species was studied by the two-color fluorescence in situ hybridization.【Result】1)The chromosome number of 12 bamboo species was 2 n=48,and their 45S rDNA distribution on the chromosomes showed a certain diversity.①There were two 45S rDNA sites on the chromosome of P.edulis,P.edulis‘Tao kiang’,P.edulis‘Heterocycla’,P.violascens,P.vivax f.aureocaulis and P.reticulata‘Lacrima-deae’,respectively,these 45S rDNA sites were consistent in distribution position and signal strength.②There were also two 45S rDNA sites on the chromosomes of P.amabilis,P.aurea,P.dulcis and P.aureosulcata‘Spectabilis’,but one of them was stable,located at the end of the chromosome,and the other site was seriously broken and often separated from the distribution position.③Although P.nigra and P.gramineus also had two 45S rDNA sites,these two 45S rDNA differed greatly in signal strength,especially P.nigra,showing more obvious.2)The 5S rDNA also showed a certain polymorphism distribution on the chromosomes of 12 bamboo species.①P.edulis,P.edulis‘Tao kiang’and P.edulis‘Heterocycla’had similar 5S rDNA distribution with two pairs of 5S rDNA sites,of which one pair had strong signals and was located at the end of the chromosome,and another pair with weak signals was located near the middle region of the chromosome.②P.violascens,P.dulcis and P.vivax f.aureocaulis had similar 5S rDNA distribution pattern,two pairs of 5S rDNA with similar fluorescence intensity were located near the middle region of the homologous chromosomes in pair.③The distribution pattern of 5S rDNA of P.aureosulcata‘Spectabilis’,P.nigra and P.gramineus was special,with three asymmetry 5S rDNA sites.As for P.nigra,two 5S rDNA sites were located at the end of chromosome in pair and another one was located near the middle region of a chromosome region alone.As for P.aureosulcata‘Spectabilis’,two different 5S rDNA sites were located near the middle region of the chromosome,and another one was located at the end of chromosome alone.However,three 5S rDNA sites of P gramineus were all located near the middle region of the chromosome.④The 5S rDNA distribution of P.reticulata‘Lacrima-deae’and P.aurea was similar,with two pairs of weak 5S rDNA signal sites that were located near the middle region of the chromosome.⑤P.amabilis had a pair of 5S rDNA sites with weak signal,which were located near the centromere region of short arm of the chromosome.【Conclusion】1)According to the distribution characteristics of 45S rDNA and 5S rDNA of the chromosomes of P.aureosulcata‘Spectabilis’,P.nigra,P.aurea,P.dulcis,P.gramineus and P.amabilis,we speculate that these bamboo species may have undergone chromosome rearrangement such as fracture,translocation,deletion or insertion.2)P.edulis,P.edulis‘Tao kiang’and P.edulis‘Heterocycla’have similar 45S rDNA and 5S rDNA distribution pattern,which is consistent with their phylogenesis classification result.