Phenotypic Variation Of Different Mutants In Chinese Cabbage

Artificial created mutant is one of ways to innnovate new germplasm in Chinese cabbage. In the present research, phenotypic traits were surveyed and mutants with interesting traits were selected in 1240 plants from 98 M2 generation, 25 M3 families, 48 DHM2 families derived from mutagenic treatment with EMS. At the same time, mutants resistance to soft rot were screened through inoculation of soft rot bacteria for 900 seedlings of 300 M2 families. Aims were to gain useful mutants and to broaden breeding population genetic background in Chinese cabbage. This research will offer basic materials to germplasm innovation, new varieties breeding and functional genomics research in Chinese cabbage. Main results are as follows:1) In M2 generation, in total 26 leaf color mutants, 25 leaf shape mutants, 24 plant type mutants were obtained. In M3 family, 37 leaf color mutants from two M3 families, 41 leaf shape mutants from one M3 family, 57 plant type mutants from one M3 family, 14 head overlapped mutants from one M3 family were obtained.2) Through the investigation and analysis to phenotypic variation separation, within a same mutation group one character separation was mostly characterized, only eight M2 generations showed separation of two different characters. In M2 generation, 16 of them appeared variation separation of leaf color trait, 14 of them appeared leaf shape variation separation, 13 of them appear plant type variation separation. In general the separation proportion of variation characteristics was different in different M2 generations. Two M3 families appeared heading time variation separation, the proportion of without heading plants and late heading plants was 4:11 and 10:6.3) In 98 M2 generations, more than two plants of same mutation were observed in 7 M2 families. In CG56, plant height, plant width, blade width, leaf length, leaf SPAD value of 4 plants was significantly lower than in wild type; in one plant with characteristics of green leaves and heading in late stage. In CG44, in 3 mutants leaf SPAD value was significantly lower than in wild type and variation characteristics of leaf was yellow; in one mutant SPAD value was low, and leaf color was light yellow at late stage. In 3 mutants in CC20 and five mutants in FL143, plant height and plant width were significantly lower than in wild type. In B205 family, in four mutants plant height, plant width were significantly lower than in wild type, but without clear differences at heading stage. In CC28, in two mutants plant height and plant width were significantly lower than in wild type, in one mutant plant type had large difference at early stage but much close at late stage. In EJ20, in 4 mutants plant type was shrinkage and plant height was significantly lower than in wild type.4) In 25 M3 families, within three of them there were uniform variation traits. In 6-18-4, SPAD value of all plants was significantly lower than in parent ‘A03’, with yellow leaf. In 6-17-8, plant height, plant width, blade width, leaf length, and leafSPAD in mutants were significantly lower than in wild type, but with new green and width leaf at late stage. In 5-38-13, plant type was more flat and plant height was significantly lower than that in parent ‘A03’, some of plant formed head at late stage.5) By comparing the phenotypic results of 78 M2 generations in two consecutive years, 16.7% of them appeared the same variation traits in two years. The repeat frequency of variation types was 33.3% of head overlapped variation, 17.6% of leaf color variation, 15.0% of plant type variation, 14.2% of leaf shape variation.6) Variation traits in 12 M3 families and their corresponding M2 generations were compared. Results showed that 5 M3 families had variation traits appeared in M2, one M3 family appear separation of variation traits in M2, 6 M3 families did not present variation traits appeared in M2 generation.7) Soft rot resistance in 900 individuals derived from 300 different M2 generations was identified. Results showed that 85 resistant mutants from 76 M2 were obtained in the used population, with 0.94% of individual survival rate.