| Plant nutrition genetics is a newly-developed intercrossed science since 1980's. The field of its research covered many mineral nutrients and stress environment, and a lot of important results have been obtained. This experiment studied boron (B) absorption, distribution and translocation of different boron efficient Cultivars of rapeseed (Brassica napus L.) at the condition of boron deficiency, then studied further the genetic law and molecular mechanism of boron nutrition efficiency with the methods of plant nutrition, genetics and modern molecular biology. The main results were as follows:1. Significant differences existed in development process and morphology between B-efficient cultivars and B-inefficient cultivars. The characteristic of B-efficient cultivars was bolting early, shorter growth period, lighter colored leaves, and littler base leaves and larger upper leaves at seedling stage. The characteristic of B-inefficient cultivars was bolting latter, longer growth period, deeper colored leaves, and larger base leaves and littler upper leaves.2. The development process of Brassic napus was not affected by different boron treatments. The statistic analyses among different B efficient cultivars and the individuals of F2 population indicated that boron efficient coefficient is significant negative related to growth period, and this two traits were tightly linked confirmed by QTL analyses. The results imply that the growth period may be used as an effective index to screen B-efficient germplasm of Brassica napus.3. Under the condition of boron deficiency (B 0.30mg/kg), the dry biomass of B-efficient cultivars was higher than that of B-inefficient cultivars, and B-efficient cultivars had larger economic coefficient at seedling stage; the averages of boron content ratio in leaf and stem in B-efficient and B-inefficient cultivars was 1:0.94 and 1:0.71, respectively, at bolting stage. The higher boron content in stem of B-efficient cultivars may be beneficial to the translocation and reuse of boron. The average of boron efficient coefficient of B-efficient cultivars was 0.917, while B-inefficient cultivars was only 0.229.4. The ability of boron translocation of B-efficient cultivars was stronger than that of B-inefficient cultivars. When boron was deficient, boron translocation coefficient of Brassica napus decreased at seedling stage, but the decreased percentage of B-efficient cultivars was much lower than that of B-inefficient cultivars; boron translocation coefficient increased at bolting stage, and B-efficient cultivars increased much more. The variance of boron translocation between B-efficient and B-inefficient cultivars at boron deficiency showed the ability of boron reuse, which may be one of main mechanisms of boron nutrition efficiency.5. The characteristics of F1 crossed between B-efficient and B-inefficient in boron absorption, translocation and agronomic traits were similar to B-efficient cultivars, this indicated that the B-efficient trait was dominant6. The studies on esterase isozymes and peroxidase isozyme of different boron efficientcultivars at various stage showed that the difference of esterase isozyme bands in leaves at seedling stage between B-efficient and B-inefficient cultivars was the clearest, which appeared in fast band district and could be distinguished easily, and it may be used as an assistant marker to identify B-efficient germplasm.7. By field experiment of two F2 populations crossed between B-inefficient and B-efficient cultivars of Brassica napus, the results obtained showed that the B-efficient trait is mainly controlled by a major gene.8. With the molecular marker technique of RFLP and AFLP, a linkage map was constructed using 128 individuals of one F2 population. The map, consisting of 87 RFLP markers and 33 AFLP markers, spanned a total of 1832.9 cM with an average interval of 15.3cM, and the major gene was located on the ninth linkage group. Genome-wide QTL analyses detected one major locus nearby the major gene, which e...
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