甘蔗染色体组构成系统演化的研究

Studies on the Genomic System Evolution of Sugarcane

用核型分析方法对甘蔗祖亲种、含两物种血缘栽培种、含三物种血缘栽培种、含四物种血缘栽培种染色体组型的系统演化特征进行了研究．从祖荣代野生种向高代杂交栽培种（含两物种血缘以上）系统演化的基本特征是：染色体数目、异染色质含量相对增加，易位现界普遍存在，中部着丝点染色体所占比例逐渐减少，核型从对称向不对称方向演化。野生种和栽培种的染色体数目分别为2n=68－92和2n=90－120；染色体约对长度为1．56－6．38μm，相对长度为1．03－4．01；染色体主要为中部着丝点染色体，少数为亚中部及亚端部着丝点染色体，未见端部着丝点染色体；除春尼为1B核型外，其余6个品种（印度割手密、墨车里本、POJ2875、Co419、F134和ROC10）全为2B类型．分别以印度割手密和春尼基因组DNA为探针，对栽培种Co419进行染色体原位杂交，结果表明，Co419（2n＝114）染色体组构成中，有6条来源于割手密种，12条来源于印度种，96条为热带种或种间重组染色体．

Systematic evolution of wild and cultivated sugarcane varieties was studied. It could be summarized that the basic laws of the systematic evolution of sugarcane are: (1) From wild varieties to cultivated ones, both chromosomes and heterochromatin increase in quantity, while the percentage of metacentric chromosomes decreases;(2)The evolution trend of Karyotypes is from symmetricalness to asymmetricalness.The chromosome number of wild and cultivar varieties were 2n=68~92 and 2n=90~120 respectively, their absolute and relative lengths being 1.56~6.382μm and 1.03~4.01 respec tively. The majority of chromosomes was metacentric, and a few of them submetacentric and subtelocentric. No telocentric chromosome was observed. Only the Kareotype of Chunnee be longed to 1B type, and the other six varieties belonged to 2B type. In the experiments the location of hybridization sites in Co419 with Co.spont and Chun nee genomic DNA probe(DIG labeled) were detected.The hybridization signal showed that 6 chromosomes were from Co. spont, 12 from Chunnee and 96 of them were intergenetic re combinant chromosomes.