高原藜米(Chenopodium quinoa Willd.)单基因性状的异源四倍体分离现象

Research on Alloletroploid Segregation Phenomena of Single-gene Morpho-logical Characters in Quinoa(Chenopodium quinoa Willd.)

高原藜米(Chenopodium quinoa Willd.)是一个异源四倍体作物,但有些研究报道该作物在单个基因位点上的分离行为有二倍体分离特征。本研究在多年观察试验的基础上,2011-2012年两年在西藏不同海拔(南木林县:海拔4 000 m;林芝:海拔2 800 m)条件下对雄性不育植株进行杂交所得的F1和F2代中分离产生了3种不同的单基因控制的性状特征进行了较大群体的观测试验。等位基因分离分析结果显示,在F1和F2的分离范围内出现了二体双基因和四体的遗传性状,在F2代减数分裂中出现的一定比例的畸变现象也显示了其不定的多价体形态,这些结果都表明了藜米的异源四倍体特征。这一特征产生的根本原因是某些基因位点重复和至少在有些同源染色体之间发生了联会现象。本研究发现,藜米某些基因位点发生的四倍体分离现象可能导致了藜米育种和遗传研究中的复杂性,对于指导该作物育种或生产都有一定的实际意义。四倍体分离,特别是其飘忽不定的现象,可能会使将来藜米基因图谱研究分析变的更加复杂,这一点在今后的研究中应给予足够的重视。

The results of previous studies indicate that the Andean grain crop quinoa is an allotetraploid, but in a few published genetic studies have concluded that a functionally diploid （disomic-monogenic） model has been ass- umed for segregation at individual loci in this species. This test is based on two years of observation, in 2011 and 2012 at the Namling （alt. 4 000 m） and Nyingchi （alt. 2 800 m） experimental stations in Tibet. Controlled crosses using male sterile plants as female parents produced Ft and F2 generations segregating for three different single- gene morphological traits. The gene segregation analysis show a range of FI and F2 ratios indicative of both disomic-digenic and tetrasomic inheritance in two of these traits, as well as distorted F2 ratios suggesting erratic multivalent formation at meiosis. These results indicate that the allotetraploidy characteristics of quinoa, with valid alleles have retained at some duplicate loci and at least some association occurring between homoeologous chromosomes. Tetrasomic segregation ratios observed in a minority of families may be due to reciprocal fragment exchange between homoeologues. The occurrence of tetraploid segregations at some loci in quinoa complicates breeding and genetic studies in the crop.