Karyotype analysis of diploid and autotetraploid of seven tartary buckwheat cultivars in China

Diploid and autotetid taraplortary buckwheat cultivars were used to conduct a karyotype study using the conventional squash method, establishing a reference for polyploid breeding. In the present study, the seven cultivars exhibited similar karyotypic features in both diploid and autotetraploid accessions. The diploid chromosome number was 2n = 2x = 16, whereas it was 2n = 2x = 32 in the autotetraploid accessions. No. T6, T9, T18, T22, T27 and T36 contained one pair of SAT chromosomes, whereas No. T25 had two pairs. Compared with diploids, the total number of chromosomes and SAT chromosomes doubled in autotetraploids. However, the karyotype asymmetry coefficient for the seven diploids ranged from 59.38–61.78%, and for the autotetraploids, it ranged from 59.73–61.76%. Additionally, the karyotype of autotetraploids remained unchanged in 2A type cases. Chromosome doubling did not affect the evolutionary relationship or clustering of tartary buckwheat (P < 0.01). The karyotypes and chromosome numbers of these seven autotetraploid cultivars have been reported for the first time.