土壤缺硼导致作物减产是我国农业生产中存在的普遍问题。甘蓝型油菜对缺硼敏感，然而不同品种对缺硼的抗性有极显著的基因型差异。本研究在前期定位硼高效主效QTL qBEC-A3a及其近等基因系（NILs）的基础上，利用BC4F4和BC4F4:5家系，克隆qBEC-A3a基因，揭示其硼高效的生物学功能和分子调控机制。主要研究内容为：1）利用上述精细定位群体和与qBEC-A3a紧密连锁的分子标记，在目标区段内寻找交换单株，精细定位qBEC-A3a，同时结合NILs及其亲本的基因表达谱，确定候选基因。2）分离候选基因的全长序列，构建超表达和RNAi载体，进行候选基因的功能互补验证，分析候选基因在转基因株系中的表达、硼的吸收、转运和利用等；3）开展候选基因启动子活性分析、组织和细胞定位等研究。研究结果揭示油菜硼高效的分子机理、为作物硼营养的遗传改良提供硼高效基因和分子标记，有重要的理论和实践意义。

Crop yield decrease due to soil boron (B) deficiency is a major agricultural problem in many regions in China. Brassica napus is extremely sensitive to B deficiency, but significant genotypic variations were observed among a wide range of Brassica napus cultivars in response to B deficiency. Based on the mapping of a main-effect B efficiency QTL qBEC-A3a in Brassica napus and the development of near-isogenic lines (NILs) of the QTL, the aim of this project is to cloning the qBEC-A3a gene and characterize its biological functions by using BC4F4 and BC4F4:5 as fine mapping populations. The main researches include: 1) With the fine mapping population and the molecular markers tightly linking to qBEC-A3a, the substitution lines and co-segregation molecular markers happened in the target chromosome region would be selected for fine mapping the qBEC-A3a. And then the candidate genes would be obtained by combining the fine mapping with the gene expression profile analysis from the NILs and their parents responding to B deficiency. 2) To isolate the full-length sequence of the candidate genes and then construct the vectors with over- or RNAi expressions, which will be used to transform Brassica napus, Arabidopsis ecotype Col-0 and mutants of bor1, nip5;1, nip6;1 for conducting the complementary experiments of gene functions. The transgenic plants will be analyzed in gene expression, uptake, transport and utilization of B. 3) to analyze the promoter sequence of the candidate genes and characterize its expressions in tissue, cellular and subcellular levels in both Brassica napus and Arabidopsis. The study will elucidate the underlying molecular mechanism of B efficiency in Brassica napus, and provide B-efficient genes and molecular markers for genetic improvement of B efficiency in Brassica napus, as well as other crops sensitive to B deficiency.