荞麦野生种的核型及进化特征分析

荞麦起源于我国西南地区,该地区分布着丰富的荞麦野生种,剖析野生荞麦的核型特征对荞麦进化和育种研究具有重要的意义。本研究以甜荞近缘种、硬枝万年荞、疏穗小野荞、细柄野荞、齿翅野荞为试验材料,采用常规压片法进行核型鉴定。结果表明:甜荞近缘种、硬枝万年荞和疏穗小野荞都为二倍体,核型公式分别为2n=2x=16=12M+4m(2SAT)、2n=2x=16=16M、2n=2x=16=14M+2m(2SAT),而细柄野荞和齿翅野荞为四倍体,核型公式分别为2n=4x=32=32M、2n=4x=32=30M+2m(2SAT)。甜荞近缘种和硬枝万年荞核型属1A型,疏穗小野荞、细柄野荞和齿翅野荞核型属1B型,并且甜荞近缘种、疏穗小野荞和齿翅野荞都有1对随体染色体。研究证明,荞麦野生种染色体的基数为8,有二倍体和四倍体野生荞麦。通过比较分析,硬枝万年荞在进化地位上比较原始,齿翅野荞是比细柄野荞较进化的四倍体荞麦野生种。

Analysis of Karyotypes and Evolutionary Features of Wild Species of Buckwheat

Buckwheat was originated in southwest of China, where exists a large number of wild relatives. Wild buckwheat karyotype feature analysis has important implications for buckwheat breeding practices. In this study, F.esculentum ssp.ancestralis,F.urophyllum, F.leptopodum var.grossii, F.gracilipes, F.gracilipes var. odontopterum were selected as experimental material and karyotypes of these species were identified by squash method. The results showed that F.esculentum ssp.ancestralis,F.urophyllum and F.leptopodum var.grossii were all diploid, the karyotype formula were 2n=2x=16=12M 4m(2SAT), 2n = 2x = 16 = 16M, 2n = 2x = 16 = 14M 2m(2SAT), while that of F.gracilipes and F.gracilipes var. odontopterum were tetraploid, and the karyotype formula were 2n=4x=32=32M and 2n=4x=32=30M 2m(2SAT). Karyotype genus type F.esculentum ssp.ancestralis and F.urophyllum was 1A, and the rests were 1B. F.esculentum ssp.ancestralis, F.leptopodum var.grossii, F.gracilipes var.odontopterum had one pair of satellite chromosomes. It proved that basic chromosome number of wild species of buckwheat were 8. There are diploid and tetraploid levels in wild buckwheat. The analysis indicated that F.urophyllum has a primitive evolutionarily status, while F.gracilipes var. odontopterum was a more advanced tetraploid buckwheat wild species in evolutionary status.