Karyotype analysis of Brassica juncea cv. bianhachi big flesh sweet mustard

Brassica juncea cv. bianhachi big flesh sweet mustard had the flat bone and thick flesh, the flesh was sweet, mouth fragrance, the less fiber, and with high quality characteristic. Moreover, the market demand for this variety is large and popular with gourmets and restaurants. In this research, we try to obtain cytological parameters on ’bianhachi big flesh sweet mustard’. The experiment results showed that the maximum chromosome length was measured 4.72 µm and max arm ratio was determined 2.25, relative length ranged between 3.08% to 8.29%. There are four types of relative length, including short (S), medium short (M1), medium long (M2) and long (L) chromosomes. In addition, the maximum centromeric index was measured in 44.60%, centromere type were submetacentric chromosomes (sm) and metacentric chromosomes (m). Karyotype asymmetry index was 61.561%, and the karyotype formula was 2n=2x=36=24m+12sm. The karyotype characteristics was type 2B according to Stebbins’s classification criteria. According to the above information, we can drawn a conclusion that ’bianhachi big flesh sweet mustard’ is a relatively primitive mustard variety. The findings revealed its karyotypic characteristics of ’bianhachi big flesh sweet mustard’ from the cytogenetic aspects. The results also provided the basis and reference for the inheritance and breeding, identification and development of mustard germplasm resources.