Biochemical And Molecular Markers And Genetic Model Analysis Of Bolting Traits In Non-Heading Chinese Cabbage

The objective of this paper was to study physiological and biochemical studies in the pro and post bolting and correlative analysis between bolting tolerance and physiological characters and the molecular markers of late-bolting and inheritance for date of bolting in non-heading Chinese Cabbage(Brassica campestris ssp. chinensis Makino).The results were as follows:1. Parents and F1 of non-heading Chinese cabbage having significantly different bolting traits were used as test materials, their leaves, buds and flowers at stages of vegetative growth, button appearance, early bolting, initial flowering and full flowering were determined in terms of SOD, POD, CAT, MDA, soluble protein, soluble sugar and proline. The results showed that the SOD, POD, CAT and MDA first decreased, then increased, but subsequently presented a downward tendency; the soluble protein content first rose and then showed a fall trend while the soluble sugar content first fell and then rose; the proline content showed an upward trend, and among different strains there were certain differences.2. By analysis correlations of bolting tolerance and POD activity, soluble protine contents, soluble sugar contents and proline contents during bolting in three non-heading Chinese cabbage cultivars whose bolting tolerance characters are significantly different, the result shows that soluble protine contents, soluble sugar contents and proline contents have a significant positive correlation with bolting tolerance, while POD activity has a significant negative correlation with bolting tolerance. Therefore, POD activity, soluble protine contents, soluble sugar contents and proline contents can all be used as identification indexes for bolting tolerance.3. Bulked Segregant Analysis (BSA), Random Amplified Polymorphic DNA (RAPD) and Sequence-Related Amplified Polymorphism (SRAP) methods were used to analyze F2 individuals of P-27×P-28 to screen and characterize the molecular marker linked to late-bolting gene in non-heading Chinese cabbage. A total of 200 random primers were used for RAPD analysis. One RAPD marker S265750 was identified to be co-segregating with the late-bolting gene, and the genetic distances between S265750 and late-bolting gene was 3.14cM. After SRAP-PCR analysis with 60 pairs primers, one SRAP marker, ME9-EM5 was identified to be co-segregating with late-bolting gene, while after the analysis of 255 F2 individuals, the marker ME9-EM5 was determined not co-segregating with the late-bolting.4. One set of data for the P1, P2, Fi, B1, B2 and F2 populations were used to perform the inheritance of bolting time of non-heading Chinese cabbage in this study were derived from two parent inbred lines P-27×P-28 with different bolting trait, respectively. The joint segregation analysis of a mixed major gene plus poly-gene genetic model was conducted to study the inheritance of bolting time in non-heading Chinese cabbage, in 2010. The frequency distributions of bolting time in F2 populations show characteristics of a mixed normal distribution, which indicated that the inheritance of bolting time followed a major gene plus poly-gene model (the D-2 model). That is, bolting time in non-heading Chinese cabbage is controlled by one additive major gene plus additive and dominance poly-genes. The major gene heritability is lower than the poly-genes heritability. Variance of environment is high in total variance. It is easy to be affected by environment.